Novel breast cancer susceptibility loci under linkage peaks identified in African ancestry consortia

BACKGROUND

Expansion of genome-wide association studies across population groups is needed to improve our understanding of shared and unique genetic contributions to breast cancer. We performed association and replication studies guided by a priori linkage findings from African ancestry (AA) relative pairs.

METHODS

We performed fixed-effect inverse-variance weighted meta-analysis under three significant AA breast cancer linkage peaks (3q26-27, 12q22-23, and 16q21-22) in 9241 AA cases and 10 193 AA controls. We examined associations with overall breast cancer as well as estrogen receptor (ER)-positive and negative subtypes (193,132 SNPs). We replicated associations in the African-ancestry Breast Cancer Genetic Consortium (AABCG).

RESULTS

In AA women, we identified two associations on chr12q for overall breast cancer (rs1420647, OR = 1.15, p = 2.50×10-6; rs12322371, OR = 1.14, p = 3.15×10-6), and one for ER-negative breast cancer (rs77006600, OR = 1.67, p = 3.51×10-6). On chr3, we identified two associations with ER-negative disease (rs184090918, OR = 3.70, p = 1.23×10-5; rs76959804, OR = 3.57, p = 1.77×10-5) and on chr16q we identified an association with ER-negative disease (rs34147411, OR = 1.62, p = 8.82×10-6). In the replication study, the chr3 associations were significant and effect sizes were larger (rs184090918, OR: 6.66, 95% CI: 1.43, 31.01; rs76959804, OR: 5.24, 95% CI: 1.70, 16.16).

CONCLUSION

The two chr3 SNPs are upstream to open chromatin ENSR00000710716, a regulatory feature that is actively regulated in mammary tissues, providing evidence that variants in this chr3 region may have a regulatory role in our target organ. Our study provides support for breast cancer variant discovery using prioritization based on linkage evidence.

Polygenic risk scores for prediction of breast cancer risk in women of African ancestry: a cross-ancestry approach

Polygenic risk scores (PRSs) are useful for predicting breast cancer risk, but the prediction accuracy of existing PRSs in women of African ancestry (AA) remains relatively low. We aim to develop optimal PRSs for the prediction of overall and estrogen receptor (ER) subtype-specific breast cancer risk in AA women. The AA dataset comprised 9235 cases and 10 184 controls from four genome-wide association study (GWAS) consortia and a GWAS study in Ghana. We randomly divided samples into training and validation sets. We built PRSs using individual-level AA data by a forward stepwise logistic regression and then developed joint PRSs that combined (1) the PRSs built in the AA training dataset and (2) a 313-variant PRS previously developed in women of European ancestry. PRSs were evaluated in the AA validation set. For overall breast cancer, the odds ratio per standard deviation of the joint PRS in the validation set was 1.34 [95% confidence interval (CI): 1.27-1.42] with the area under receiver operating characteristic curve (AUC) of 0.581. Compared with women with average risk (40th-60th PRS percentile), women in the top decile of the PRS had a 1.98-fold increased risk (95% CI: 1.63-2.39). For PRSs of ER-positive and ER-negative breast cancer, the AUCs were 0.608 and 0.576, respectively. Compared with existing methods, the proposed joint PRSs can improve prediction of breast cancer risk in AA women.

Evaluating Polygenic Risk Scores for Breast Cancer in Women of African Ancestry

BACKGROUND

Polygenic risk scores (PRSs) have been demonstrated to identify women of European, Asian, and Latino ancestry at elevated risk of developing breast cancer (BC). We evaluated the performance of existing PRSs trained in European ancestry populations among women of African ancestry.

METHODS

We assembled genotype data for women of African ancestry, including 9241 case subjects and 10 193 control subjects. We evaluated associations of 179- and 313-variant PRSs with overall and subtype-specific BC risk. PRS discriminatory accuracy was assessed using area under the receiver operating characteristic curve. We also evaluated a recalibrated PRS, replacing the index variant with variants in each region that better captured risk in women of African ancestry and estimated lifetime absolute risk of BC in African Americans by PRS category.

RESULTS

For overall BC, the odds ratio per SD of the 313-variant PRS (PRS313) was 1.27 (95% confidence interval [CI] = 1.23 to 1.31), with an area under the receiver operating characteristic curve of 0.571 (95% CI = 0.562 to 0.579). Compared with women with average risk (40th-60th PRS percentile), women in the top decile of PRS313 had a 1.54-fold increased risk (95% CI = 1.38-fold to 1.72-fold). By age 85 years, the absolute risk of overall BC was 19.6% for African American women in the top 1% of PRS313 and 6.7% for those in the lowest 1%. The recalibrated PRS did not improve BC risk prediction.

CONCLUSION

The PRSs stratify BC risk in women of African ancestry, with attenuated performance compared with that reported in European, Asian, and Latina populations. Future work is needed to improve BC risk stratification for women of African ancestry.

Cross-ancestry GWAS meta-analysis identifies six breast cancer loci in African and European ancestry women

Our study describes breast cancer risk loci using a cross-ancestry GWAS approach. We first identify variants that are associated with breast cancer at P < 0.05 from African ancestry GWAS meta-analysis (9241 cases and 10193 controls), then meta-analyze with European ancestry GWAS data (122977 cases and 105974 controls) from the Breast Cancer Association Consortium. The approach identifies four loci for overall breast cancer risk [1p13.3, 5q31.1, 15q24 (two independent signals), and 15q26.3] and two loci for estrogen receptor-negative disease (1q41 and 7q11.23) at genome-wide significance. Four of the index single nucleotide polymorphisms (SNPs) lie within introns of genes (KCNK2, C5orf56, SCAMP2, and SIN3A) and the other index SNPs are located close to GSTM4, AMPD2, CASTOR2, and RP11-168G16.2. Here we present risk loci with consistent direction of associations in African and European descendants. The study suggests that replication across multiple ancestry populations can help improve the understanding of breast cancer genetics and identify causal variants.

Abstract 4613: Cross-ancestry genome-wide association study identifies six new loci for breast cancer in women of African and european ancestry

Background: Over 180 genetic variants have been identified as risk loci for breast cancer. However, most loci were discovered using European ancestry populations. As some common susceptibility loci are shared across populations, we aim to discover new risk loci for breast cancer using a cross-ancestry genome-wide association study (GWAS) approach.

Methods: Data from five GWAS studies in women of African ancestry with a combined sample size of 9241 cases and 10192 controls were used to generate pooled breast cancer risk estimates in a fixed effect meta-analysis, and this served as the discovery dataset. Summary statistics from the GWAS conducted in European ancestry populations (Breast Cancer Association Consortium, 122977 cases and 105974 controls) served as the validation dataset. The variants that were associated with breast cancer risk at P &lt; 0.01 in the GWAS of African ancestry were meta-analyzed with the GWAS in European ancestry. A locus was considered novel if the lead index variant was genome-wide significant (5 × 10−8) in the cross-ancestry meta-analysis and &gt;500kb away from known breast cancer risk loci. Conditional on the lead index variants, we searched for additional signals in each locus using multivariable logistic regression. Analyses were done separately for ER-positive, ER-negative and overall breast cancer risk.

Results: We discovered four novel loci for overall breast cancer risk (1p13.3, 5q31.1, 15q24, and 15q26.3) and two novel loci for ER-negative breast cancer (1q41 and 7q11.23) at the genome-wide significance level of P &lt; 5 × 10−8. Three index single nucleotide polymorphism (SNPs) lie within introns of genes (KCNK2, C5orf56, and SIN3A) and the other index SNPs are located in intergenic regions (close to GSTM4 and AMPD2, CASTOR2, and the antisense DNA RP11-168G16.2). The direction of the associations was consistent between the GWASs of African and European descendants. At the 15q24 locus, we found an additional SNP (in the intron of the SCAMP2 gene) to be independently associated with overall breast cancer risk.

Conclusions: We have identified six new risk loci that may contribute to better prediction of breast cancer risk in African ancestry populations and provide new insights into mechanisms of breast cancer carcinogenesis. Replication of these loci in multiple populations and functional studies can help to identify causal variants.

Citation Format: Babatunde Adedokun, Zhaohui Du, Guimin Gao, Thomas Ahearn, Kathryn L. Lunetta, Gary Zirpoli, Jonine Figueroa, Esther M. John, Leslie Bernstein, Wei Zheng, Jennifer J. Hu, Regina G. Ziegler, Sarah Nyante, Elisa V. Bandera, Sue A. Ingles, Michael F. Press, Sandra L. Deming, Jorge L. Rodriguez-Gil, Song Yao, Temidayo O. Ogundiran, Oladosu Ojengbede, William Blot, Melissa Troester, Katherine L. Nathanson, Anselm Hennis, Barbara Nemesure, Stefan Ambs, Lara E. Sucheston-Campbell, Jeannette T. Bensen, Stephen J. Chanock, Andrew F. Olshan, Christine B. Ambrosone, David V. Conti, Olufunmilayo I. Olopade, Montserrat Garcia-Closas, Julie R. Palmer, Christopher A. Haiman, Dezheng Huo. Cross-ancestry genome-wide association study identifies six new loci for breast cancer in women of African and european ancestry [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4613.

Abstract 2320: Evaluating a polygenic risk score for breast cancer in women of African ancestry

Background: A polygenic risk score (PRS) for breast cancer including 313 common variants developed by the Breast Cancer Association Consortium (BCAC) has been demonstrated to identify women who are at high risk of developing breast cancer [odds ratio (OR 95%CI) = 1.61 (1.57-1.65) per SD] in women of European ancestry. In the present study, we examined the performance of the 313-variant PRS and a PRS including 179 variants reaching genome-wide significance in previous genome-wide association studies (GWAS), in women of African ancestry.

Methods: We assembled genotype data for women of African ancestry from 28 breast cancer studies, including a total of 9,241 cases and 10,193 controls. We constructed the 179-variant and 313-variant PRSs with relative risk weights for each variant estimated in women of European ancestry in BCAC. The associations between the two PRSs and overall, ER+ and ER- breast cancer risk were estimated using logistic regression adjusting for age, study site and principal components. Discriminatory accuracy of the PRSs was evaluated using the receiver operating characteristic curve (AUROC). We then recalibrated the 179-variant PRS by replacing index variants with variants in each region that better captured risk in women of African ancestry and used relative risk weights estimated in women of African ancestry. We also assessed PRS performance by age (&lt;55 versus ≥ 55 years).

Results: Both the 179 and 313- variant PRSs were significantly associated with overall, ER+ and ER- breast cancer risk, with odds ratios (OR) per standard deviation of 1.21~1.37 and AUROCs ranging from 0.57 to 0.59. The 179-variant PRS outperformed in ER- cancer [1.31(1.24,1.37) per SD] while the 313-SNP PRS was better for overall [1.27(1.23,1.31) per SD] and ER+ cancer [1.37(1.32,1.43) per SD]. For overall breast cancer, compared to women with average risk (40th-60th PRS percentiles), women in the top decile of PRS had a 1.54 (95% CI: 1.38, 1.72)-fold increased risk. The performance of the recalibrated 179-variant PRS was not improved (average AUROC=0.56). The PRS ORs did not differ significantly across age strata (P-value for age interaction = 0.63).

Conclusion: Our study shows that both 179 and 313 variant PRS stratify breast cancer risk in women of African ancestry, with attenuated performance compared to that reported in European and in Latina populations. Future work is needed to improve breast cancer risk stratification for women of African ancestry.

Citation Format: Zhaohui Du, Guimin Gao, Babatunde Adedokun, Thomas Ahearn, Kathryn L. Lunetta, Gary Zirpoli, Melissa Troester, Edward A. Ruiz-Narváez, Stephen Haddad, Jonine Figueroa, Esther M. John, Leslie Bernstein, Wei Zheng, Jennifer J. Hu, Regina G. Ziegler, Sarah Nyante, Elisa V. Bandera, Sue A. Ingles, Michael F. Press, Sandra L. Deming, Jorge L. Rodriguez-Gil, Song Yao, Temidayo O. Ogundiran, Oladosu A. Ojengbede, William Blot, Katherine L. Nathanson, Anselm Hennis, Barbara Nemesure, Stefan Ambs, Lara E. Sucheston-Campbell, Jeannette T. Bensen, Stephen J. Chanock, Andrew F. Olshan, Christine B. Ambrosone, David V. Conti, Olufunmilayo I. Olopade, Julie R. Palmer, Montserrat Garcia-Closas, Dezheng Huo, Christopher A. Haiman. Evaluating a polygenic risk score for breast cancer in women of African ancestry [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2320.

Impact of axillary node-positivity and surgical resection margins on survival of women treated for breast cancer in Ibadan, Nigeria

Introduction

Oncologic surgical extirpation, the mainstay of loco-regional disease control in breast cancer, is aimed at achieving negative margins and lymph node clearance. Even though axillary lymph nodal metastasis is a critical index of prognostication, establishing the impact of lymph node ratio (LNR) and adequate surgical margins on disease-specific survivorship would be key to achieving longer survival. This study examines the prognostic role of pN (lymph nodes positive for malignancy), LNR and resection margin on breast cancer survival in a tertiary hospital in Ibadan, Nigeria.

Methods

We conducted a longitudinal cohort study of 225 patients with breast carcinoma, documented clinico-pathologic parameters and 5-year follow up outcomes - distant metastasis and survival. Chi-square test and logistic regression analysis were used to evaluate the interaction of resection margin and proportion of metastatic lymph nodes with patients' survival. The receiver operating characteristic curve was plotted to determine the proportion of metastatic lymph nodes which predicted survival. The survival analysis was done using Kaplan-Meier method.

Results

Sixty (26.7%) patients of the patients had positive resection margins, with the most common immuno-histochemical type being Lumina A. 110 (49%) patients had more than 10 axillary lymph nodes harvested. The mean age was 48.6 ± 11.8 years. Tumour size (p = 0.018), histological type (p = 0.015), grade (p = 0.006), resection margin (p = 0.023), number of harvested nodes (p < 0.01), number of metastatic nodes (p < 0.001) and loco-regional recurrence (p < 0.01) are associated with survival. The overall 5-year survival was 65.3%.

Conclusion

Unfavourable survival outcomes following breast cancer treatment is multifactorial, including the challenges faced in the multimodal treatment protocol received by our patients.

Breast Cancer Knowledge Assessment of Health Workers in Ibadan, Southwest Nigeria

PURPOSE

Breast cancer is the most common cancer among women, and in low- to middle-income countries late-stage diagnosis contributes to significant mortality. Previous research at the University College Hospital, a tertiary hospital in Ibadan, Nigeria, on social factors contributing to late diagnosis revealed that many patients received inappropriate initial treatment.

METHODS

The level of breast cancer knowledge among health practitioners at various levels of the health system was assessed. We developed a tool tailored to local needs to assess knowledge of symptoms, risk factors, treatments, and cultural beliefs. The recruitment included doctors, nurses, and pharmacists in public hospitals, physicians and pharmacists in private practice, nurses and health care workers from primary health care centers, community birth attendants, and students in a health care field from state schools.

RESULTS

A total of 1,061 questionnaires were distributed, and 725 providers responded (68%). Seventy-eight percent were female, and > 90% were Yoruba, the dominant local ethnic group. The majority were Christian, and 18% were Muslim. Median knowledge score was 31 out of 56, and the differences in scores between health care worker types were statistically significant (P < .001). Nearly 60% of the participants believed breast cancer is always deadly. More than 40% of participants believed that keeping money in the bra causes breast cancer, and approximately 10% believed that breast cancer is caused by a spiritual attack.

CONCLUSION

Our questionnaire revealed that, even at the tertiary care level, significant gaps in knowledge exist, and knowledge of breast cancer is unacceptably low at the level of community providers. In addition to efforts aimed at strengthening health systems, greater knowledge among community health care workers has the potential to reduce delays in diagnosis for Nigerian patients with breast cancer.

Inherited Breast Cancer in Nigerian Women

PURPOSE

Among Nigerian women, breast cancer is diagnosed at later stages, is more frequently triple-negative disease, and is far more frequently fatal than in Europe or the United States. We evaluated the contribution of an inherited predisposition to breast cancer in this population.

PATIENTS AND METHODS

Cases were 1,136 women with invasive breast cancer (mean age at diagnosis, 47.5 ± 11.5 years) ascertained in Ibadan, Nigeria. Patients were selected regardless of age at diagnosis, family history, or prior genetic testing. Controls were 997 women without cancer (mean age at interview, 47.0 ± 12.4 years) from the same communities. BROCA panel sequencing was used to identify loss-of-function mutations in known and candidate breast cancer genes.

RESULTS

Of 577 patients with information on tumor stage, 86.1% (497) were diagnosed at stage III (241) or IV (256). Of 290 patients with information on tumor hormone receptor status and human epidermal growth factor receptor 2, 45.9% (133) had triple-negative breast cancer. Among all cases, 14.7% (167 of 1,136) carried a loss-of-function mutation in a breast cancer gene: 7.0% in BRCA1, 4.1% in BRCA2, 1.0% in PALB2, 0.4% in TP53, and 2.1% in any of 10 other genes. Odds ratios were 23.4 (95% CI, 7.4 to 73.9) for BRCA1 and 10.3 (95% CI, 3.7 to 28.5) for BRCA2. Risks were also significantly associated with PALB2 (11 cases, zero controls; P = .002) and TP53 (five cases, zero controls; P = .036). Compared with other patients, BRCA1 mutation carriers were younger ( P < .001) and more likely to have triple-negative breast cancer ( P = .028).

CONCLUSION

Among Nigerian women, one in eight cases of invasive breast cancer is a result of inherited mutations in BRCA1, BRCA2, PALB2, or TP53, and breast cancer risks associated with these genes are extremely high. Given limited resources, prevention and early detection services should be especially focused on these highest-risk women.

Genetic variation in the Hippo pathway and breast cancer risk in women of African ancestry

Gene expression changes within the Hippo pathway were found to be associated with large tumor size and metastasis in breast cancer. The combined effect of genetic variants in genes of this pathway may have a causal role in breast cancer development. We examined 7086 SNPs that were not highly correlated (r²  < 0.8) in 35 Hippo pathway genes using data from the genome-wide association study of breast cancer from the Root Consortium, which includes 3686 participants of African ancestry from Nigeria, United States of America, and Barbados: 1657 cases (403 estrogen receptor-positive [ER+], 374 ER-) and 2029 controls. Gene-level analyses were conducted using improved AdaJoint test for large-scale genetic association studies adjusting for age, study site and the first four eigenvectors from the principal component analysis. SNP-level analyses were conducted with logistic regression. The Hippo pathway was significantly associated with risk of ER+ breast cancer (pathway-level P = 0.019), with WWC1 (P_adj = 0.04) being the leading gene. The pathway-level significance was lost without WWC1 (P = 0.12). rs147106204 in the WWC1 gene was the most statistically significant SNP after gene-level adjustment for multiple comparisons (OR = 0.53, 95%CI = 0.41-0.70, P_adj  = 0.025). We found evidence of an association between genetic variations in the Hippo pathway and ER+ breast cancer. Moreover, WWC1 was identified as the most important genetic susceptibility locus highlighting the importance of genetic epidemiology studies of breast cancer in understudied populations.

Genome-wide association studies in women of African ancestry identified 3q26.21 as a novel susceptibility locus for oestrogen receptor negative breast cancer

Multiple breast cancer loci have been identified in previous genome-wide association studies, but they were mainly conducted in populations of European ancestry. Women of African ancestry are more likely to have young-onset and oestrogen receptor (ER) negative breast cancer for reasons that are unknown and understudied. To identify genetic risk factors for breast cancer in women of African descent, we conducted a meta-analysis of two genome-wide association studies of breast cancer; one study consists of 1,657 cases and 2,029 controls genotyped with Illumina’s HumanOmni2.5 BeadChip and the other study included 3,016 cases and 2,745 controls genotyped using Illumina Human1M-Duo BeadChip. The top 18,376 single nucleotide polymorphisms (SNP) from the meta-analysis were replicated in the third study that consists of 1,984 African Americans cases and 2,939 controls. We found that SNP rs13074711, 26.5 Kb upstream of TNFSF10 at 3q26.21, was significantly associated with risk of oestrogen receptor (ER)-negative breast cancer (odds ratio [OR]=1.29, 95% CI: 1.18-1.40; P = 1.8 × 10 − 8). Functional annotations suggest that the TNFSF10 gene may be involved in breast cancer aetiology, but further functional experiments are needed. In addition, we confirmed SNP rs10069690 was the best indicator for ER-negative breast cancer at 5p15.33 (OR = 1.30; P = 2.4 × 10 − 10) and identified rs12998806 as the best indicator for ER-positive breast cancer at 2q35 (OR = 1.34; P = 2.2 × 10 − 8) for women of African ancestry. These findings demonstrated additional susceptibility alleles for breast cancer can be revealed in diverse populations and have important public health implications in building race/ethnicity-specific risk prediction model for breast cancer.

Association of Pancreatic Cancer Susceptibility Variants with Risk of Breast Cancer in Women of European and African Ancestry

Background: Pancreatic cancer mutation signatures closely resemble breast cancer, suggesting that both cancers may have common predisposition mechanisms that may include commonly inherited SNPs.Methods: We examined 23 genetic variants known to be associated with pancreatic cancer as breast cancer risk factors in the Root genome-wide association study (GWAS; 1,657 cases and 2,029 controls of African diaspora) and GAME-ON/DRIVE GWAS (16,003 cases and 41,335 controls of European ancestry).Results: None of the pancreatic cancer susceptibility variants were individually associated with breast cancer risk after adjustment for multiple testing (at α = 0.002) in the two populations. In Root GWAS, a change by one SD in the polygenic risk score (PRS) was not significantly associated with breast cancer. In addition, we did not observe a trend in the relationship between PRS percentiles and breast cancer risk.Conclusions: The association between reported pancreatic cancer genetic susceptibility variants and breast cancer development in women of African or European ancestry is likely weak, if it does exist.Impact: Known GWAS-derived susceptibility variants of pancreatic cancer do not explain its shared genetic etiology with breast cancer. Cancer Epidemiol Biomarkers Prev; 27(1); 116-8. ©2017 AACR.

Association of breast cancer risk and the mTOR pathway in women of African ancestry in 'The Root' Consortium

Functional studies have elucidated the role of the mammalian target of rapamycin (mTOR) pathway in breast carcinogenesis, but to date, there is a paucity of data on its contribution to breast cancer risk in women of African ancestry. We examined 47628 SNPs in 61 mTOR pathway genes in the genome wide association study of breast cancer in the African Diaspora study (The Root consortium), which included 3686 participants (1657 cases). Pathway- and gene-level analyses were conducted using the adaptive rank truncated product (ARTP) test for 10994 SNPs that were not highly correlated (r2 < 0.8). Odds ratio (OR) and 95% confidence interval (CI) were estimated with logistic regression for each single-nucleotide polymorphism. The mTOR pathway was significantly associated with overall and estrogen receptor-negative (ER-) breast cancer risk (P = 0.003 and 0.03, respectively). PRKAG3 (Padj = 0.0018) and RPS6KA3 (Padj = 0.061) were the leading genes for the associations with overall breast cancer risk and ER- breast cancer risk, respectively. rs190843378 in PRKAG3 was statistically significant after gene-level adjustment for multiple comparisons (OR = 0.50 for each T allele, 95% CI = 0.38-0.66, Padj = 3.6E-05), with a statistical power of 0.914. These results provide new insights on the biological relevance of the mTOR pathway in breast cancer progression and underscore the need for more genetic epidemiology studies of breast cancer in the African Diaspora.

Genetic variation in the vitamin D related pathway and breast cancer risk in women of African ancestry in the root consortium

The vitamin D related pathway has been evaluated in carcinogenesis but its genetic contribution remains poorly understood. We examined single-nucleotide polymorphisms (SNPs) in the vitamin D related pathway genes using data from a genome-wide association study (GWAS) of breast cancer in the African Diaspora that included 3,686 participants (1,657 cases). Pathway- and gene-level analyses were conducted using the adaptive rank truncated product test. Odds ratios (OR) and 95% confidence intervals (CI) were estimated at SNP-level. After stringent Bonferroni corrections, we observed no significant association between variants in the vitamin D pathway and breast cancer risk at the pathway-, gene-, or SNP-level. In addition, no association was found for either the reported signals from GWASs of vitamin D related traits, or the SNPs within vitamin D receptor (VDR) binding regions. Furthermore, a decrease in genetically predicted 25(OH)D levels by Mendelian randomization was not associated with breast cancer (p = 0.23). However, an association for breast cancer with the pigment synthesis/metabolism pathway almost approached significance (pathway-level p = 0.08), driven primarily by a nonsense SNP rs41302073 in TYRP1, with an OR of 1.54 (95% CI = 1.24-1.91, p_adj  = 0.007). In conclusion, we found no evidence to support an association between vitamin D status and breast cancer risk in women of African ancestry, suggesting that vitamin D is unlikely to have significant effect on breast carcinogenesis. Interestingly, TYRP1 might be related to breast cancer through a non-vitamin D relevant mechanism but further studies are needed.

Abstract 1312: Genetic variation in the Hippo pathway and breast cancer risk in women of African ancestry in the ROOT Consortium

Background: The Hippo pathway controls organ growth by regulating cell proliferation and apoptosis. To our knowledge, it is still unclear about its role in the development of breast cancer. Identifying the relevant genes and single-nucleotide polymorphisms (SNPs) should shed light on the pathway’s mechanism in carcinogenesis. Methods: We examined 47,419 SNPs in 37 Hippo pathway genes in the genome wide association study of breast cancer conducted in the African Diaspora (ROOT consortium), which included 3,686 participants of African ancestry from Nigeria, USA, and Barbados (1,657 cases and 2,029 controls). Gene-level analyses were conducted using the adaptive rank truncated product (ARTP) test for 10,771 SNPs that weren’t highly correlated (r2 &lt; 0.8), and SNP-level analyses were conducted with logistic regression. Results: The Hippo pathway was significantly associated with risk of estrogen receptor positive (ER+) breast cancer (pathway-level P=0.028). Gene-based analyses revealed that WWC1 (gene-level P=0.001) was responsible for this association, with rs116516633 in this gene being statistically significant after gene-level adjustment for multiple comparisons [odds ratio (OR) =0.53 for each G allele, 95% confidence interval (CI) =0.41-0.70, Padj=0.002]. In addition, two SNPs in LATS2 (rs142900440, OR=0.42, 95% CI: 0.28-0.64; rs58674288, OR=0.38, 95% CI =0.24-0.61) were associated with risk of ER+ breast cancer. In the analysis of ER- breast cancer risk, rs2579161 in DLG5 (OR=1.38, 95% CI: 1.17-1.63) and rs11062429 in TEAD4 (OR=1.39, 95% CI: 1.17-1.64) were statistically significant. These associations remained significant after Bonferroni-correction at the gene-wide level (all P&lt; 0.05). Conclusions: We found evidence of associations of the Hippo pathway with ER+ breast cancer risk in women of African ancestry. Our findings supported the potential mechanism that WWC1 functions as an upstream member of the pathway, and highlighted the importance of further studies.

Table 1.Gene-wide significant tested SNPs for all breast cancer, ER+ tumors or ER- tumorsAll cases vs controlsER+ cases vs controlsER- cases vs controlsGene-SNPFunctionMajor/minor allelesMinor allele frequency among controlsOR (95% CI)PadjOR (95% CI)PadjOR (95% CI)PadjOverallTEAD1-rs16911695IntronG/A0.241.24 (1.11-1.39)0.101.30 (1.07-1.58)1.001.34 (1.10-1.63)1.00ER+LATS2-rs142900440IntronT/C0.040.78 (0.61-0.98)1.000.42 (0.28-0.64)0.010.80 (0.54-1.19)1.00LATS2-rs58674288IntronC/T0.030.73 (0.56-0.95)1.000.38 (0.24-0.61)0.010.70 (0.45-1.08)1.00WWC1-rs116516633Non-coding transcript variantA/G0.100.82 (0.71-0.96)1.000.53 (0.41-0.70)0.0020.81 (0.62-1.06)1.00ER-DLG5-rs2579161Upstream gene variantG/A0.491.08 (0.98-1.19)1.000.99 (0.85-1.17)1.001.38 (1.17-1.63)0.03TEAD4-rs11062429Downstream gene variantC/G0.431.01 (0.92-1.11)1.000.94 (0.79-1.00)1.001.39 (1.17-1.64)0.047

Citation Format: Shengfeng Wang, Yonglan Zheng, Temidayo O. Ogundiran, Oladosu Ojengbede, Wei Zheng, Katherine L. Nathanson, Barbara Nemesure, Stefan Ambs, Dezheng Huo, Olufunmilayo I. Olopade. Genetic variation in the Hippo pathway and breast cancer risk in women of African ancestry in the ROOT Consortium [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1312. doi:10.1158/1538-7445.AM2017-1312

Association of breast cancer risk in women of African ancestry with genetic variants in the TET-related DNA demethylation pathway

e13015

Background: Imbalance in DNA methylation/demethylation cycles due to mutations in TET1, TET2, TET3, and TDG has been implicated in the onset and progression of breast cancer. However, few studies have assessed the relationship between genetic variants in the TET-related DNA demethylation pathway and breast cancer risk, particularly among women of African ancestry. Methods: We investigated 4095 single-nucleotide polymorphisms (SNPs) in four TET-related DNA demethylation pathway genes in the ROOT consortium, which includes women of African ancestry, in 1657 cases [403 estrogen receptor-positive (ER+) and 374 ER-negative (ER-)] and 2029 controls. Pathway and gene-level analyses were conducted using the adaptive rank truncated product (ARTP) test for 925 SNPs that were not highly correlated (r2 < 0.8), and SNP-level analyses were conducted with logistic regression, which was used to estimate the odds ratio (OR) and 95 % confidence intervals (CI). Results: The Tet-related DNA demethylation pathway was significantly associated with ER-negative breast cancer (pathway level P = 0.049). Gene-level analyses showed that TET1 was the candidate gene responsible for the association at the pathway level ( P = 0.008). SNP TET1 rs10998376 (OR = 1.21, 95% CI = 1.02-1.42, Padj = 0.0032) was statistically significant even after gene-level correction for multiple comparisons, and was associated with increased risk. There were no SNPs in genes with P > 0.05 in the ARTP tests that were significant after Boferroni correction. Conclusions: In conclusion, specific TET-related DNA demethylation pathway genes may contribute to breast cancer risk, in particular, to risk of ER-negative tumors in women of African ancestry.

Characterizing Genetic Susceptibility to Breast Cancer in Women of African Ancestry

Background: Genome-wide association studies have identified approximately 100 common genetic variants associated with breast cancer risk, the majority of which were discovered in women of European ancestry. Because of different patterns of linkage disequilibrium, many of these genetic markers may not represent signals in populations of African ancestry.Methods: We tested 74 breast cancer risk variants and conducted fine-mapping of these susceptibility regions in 6,522 breast cancer cases and 7,643 controls of African ancestry from three genetic consortia (AABC, AMBER, and ROOT).Results: Fifty-four of the 74 variants (73%) were found to have ORs that were directionally consistent with those previously reported, of which 12 were nominally statistically significant (P < 0.05). Through fine-mapping, in six regions (3p24, 12p11, 14q13, 16q12/FTO, 16q23, 19p13), we observed seven markers that better represent the underlying risk variant for overall breast cancer or breast cancer subtypes, whereas in another two regions (11q13, 16q12/TOX3), we identified suggestive evidence of signals that are independent of the reported index variant. Overlapping chromatin features and regulatory elements suggest that many of the risk alleles lie in regions with biological functionality.Conclusions: Through fine-mapping of known susceptibility regions, we have revealed alleles that better characterize breast cancer risk in women of African ancestry.Impact: The risk alleles identified represent genetic markers for modeling and stratifying breast cancer risk in women of African ancestry. Cancer Epidemiol Biomarkers Prev; 26(7); 1016-26. ©2017 AACR.

Abstract 4494: Whole genome sequencing reveals different patterns of mutational mechanisms in breast tumors between women of African and European descent

Across race/ethnicities, breast cancer incidence and mortality rates markedly differ. Numerous studies have demonstrated that individuals of African ancestry acquire aggressive, early-onset breast cancers more frequently than other populations for reasons that remain unexplained. The sources of these disparities are complex, and a comprehensive characterization of mutation landscapes amongst indigenous Africans, African Americans (AA), and Caucasian breast tumors has not been performed.

We generated high-depth whole genome sequencing on 31 Nigerian breast cancers (90x) along with matched blood (30x). Breast cancer whole genomes (tumor-normal pairs) from The Cancer Genome Atlas were harmonized with our samples, resulting in a cohort of 31 Nigerians (17 estrogen receptor negative, ER-), 31 AA (22 ER-), and 43 Caucasians (19 ER-). High confidence somatic mutations (substitutions and insertions/deletions) were obtained by using multiple variant callers. Regardless of race, ER- tumors carried similar numbers of mutations than their estrogen receptor positive (ER+) counterparts (Welch t-test p = 0.57 - 0.82). TP53 (64%) was the most frequently mutated gene in ER- disease, while canonical PIK3CA activating mutations were prevalent in ER+ cases (33.3%). Additionally, tumor suppressor genes RB1, NF1, and PTEN were disrupted via structural rearrangements in ∼6 to 15% of samples. Rearrangements in the H3K27 methylation regulator EZH1 were identified in six Caucasians but only one individual with African _ancest. Notably, within coding regions, no striking mutation rate differences amongst races were identified. However, global substitution patterns in ER+ and ER- cancers varied widely by race/ethnicity. In ER- cases, Nigerians carried the highest proportion of canonical APOBEC-associated substitutions, particularly C&gt;T transitions. Conversely, Caucasians with ER+ disease showed a higher proportion of C&gt;T than both Nigerians (Welch t-test p = 0.044) and AA (Welch t-test p = 0.011). Kataegis, or clustered mutations, was most prevalent in Nigerian samples, regardless of ER status. Evidence for kataegis was often corroborated by structural variant breakpoints and aberrant copy number states at the hypermutated locus. Mutation signature analyses highlighted multiple APOBEC signatures, with moderate contribution differences across race and ER status.

Overall, our data suggests potential mutation spectra differences in Caucasian, African American and indigenous African breast tumors. Identification of these molecular characteristics by ancestry and geography may help understand race-associated phenotypes and exposures that drive outcomes in breast cancer.

Citation Format: Jason J. Pitt, Toshio F. Yoshimatsu, Yonglan Zheng, Jason Grundstad, Jigyasa Tuteja, Jiebiao Wang, Abayomi Odetunde, Galina Khramtsova, Wendy Clayton, Adeyinka Ademola, Temidayo O. Ogundiran, Adenike T. Adeniji-Sofoluwe, Millicent Obajimi, Adewunmi Adeoye, Chinedum Babalola, Oladosu A. Ojengbede, Christopher O. Olopade, Oluwasola A. Olayiwola, Lin Chen, Dezheng Huo, Kevin P. White, Olufunmilayo I. Olopade. Whole genome sequencing reveals different patterns of mutational mechanisms in breast tumors between women of African and European descent. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4494.

Genetic variants in microRNA and microRNA biogenesis pathway genes and breast cancer risk among women of African ancestry

MicroRNAs (miRNA) regulate breast biology by binding to specific RNA sequences, leading to RNA degradation and inhibition of translation of their target genes. While germline genetic variations may disrupt some of these interactions between miRNAs and their targets, studies assessing the relationship between genetic variations in the miRNA network and breast cancer risk are still limited, particularly among women of African ancestry. We systematically put together a list of 822 and 10,468 genetic variants among primary miRNA sequences and 38 genes in the miRNA biogenesis pathway, respectively; and examined their association with breast cancer risk in the ROOT consortium which includes women of African ancestry. Findings were replicated in an independent consortium. Logistic regression was used to estimate the odds ratio (OR) and 95 % confidence intervals (CI). For overall breast cancer risk, three single-nucleotide polymorphisms (SNPs) in miRNA biogenesis genes DROSHA rs78393591 (OR = 0.69, 95 % CI: 0.55-0.88, P = 0.003), ESR1 rs523736 (OR = 0.88, 95 % CI: 0.82-0.95, P = 3.99 × 10(-4)), and ZCCHC11 rs114101502 (OR = 1.33, 95 % CI: 1.11-1.59, P = 0.002), and one SNP in primary miRNA sequence (rs116159732 in miR-6826, OR = 0.74, 95 % CI: 0.63-0.89, P = 0.001) were found to have significant associations in both discovery and validation phases. In a subgroup analysis, two SNPs were associated with risk of estrogen receptor (ER)-negative breast cancer, and three SNPs were associated with risk of ER-positive breast cancer. Several variants in miRNA and miRNA biogenesis pathway genes were associated with breast cancer risk. Risk associations varied by ER status, suggesting potential new mechanisms in etiology.

Abstract P6-04-05: Genotype-phenotype classification of triple negative breast cancers (TNBC) in women of African descent using the PAM50 NanoString platform and genomic data

Introduction: TNBC has the highest mortality rate amongst all other breast cancer types due to its complex tumor heterogeneity and lack of well-defined molecular targets. It is known that women of African descent are two to three times more likely to develop TNBC compared to women of European ancestry, yet wide-scale genomic studies of African and African American breast tumors are limited. To elucidate genotypes and molecular subtypes associated with the most aggressive forms of breast cancer, we used the PAM50 NanoString platform to reclassify Nigerian (NG), African American (AA) and Caucasian (CA) tumors previously annotated by Immunohistochemistry (IHC), and correlated our findings to their germline genotype data obtained using high-throughput technologies.

Methods: RNAs were isolated from formalin-fixed, paraffin embedded (FFPE) tumor tissues using the High Pure Paraffin Kit (Roche) following manufacturer's protocol, and assayed on NanoString nCounter Analysis System using a custom Nano110 (PAM50 + claudin-low & VEGF signatures) probe set. Intrinsic subtyping and gene-expression data were evaluated using R statistical software. All study samples were previously annotated and subtyped by the ER/PR/HER2 IHC classifier. Genotypes were obtained from next generation sequencing or Illumina Human2.5M BeadChip platform using germline DNA from more than 2000 breast cancer cases and 2000 controls were studied.

Results: To date, Intrinsic molecular subtyping by Nano110 has been completed on 69 NG, 81 AA and 74 CA tumors. Concordance between IHC and PAM50 was 59%, which is adequate and comparable to previous studies. Basal-like subtype was overrepresented and accounted for nearly 30% of NG and AA cases, compared to 17% in CA cases. HER2-enriched subtype was overrepresented only in NG cases (9%). The proportion with Luminal A tumors were 44% NG, 56% AA and 68% CA, respectively.

Conclusions: PAM50 NanoString assay is reliable and high-throughput for molecular subtyping breast cancer using RNA extracted from FFPE tumors. Ongoing work will correlate PAM50 intrinsic subtypes to genotype data.

Citation Format: Olayiwola OA, Ogundiran TO, Hardeman A, Yoshimatsu TF, Clayton W, Adeoye A, Ademola A, Ajani MA, Khramtsova G, Grushko TA, Huo D, Zheng Y, Parker J, Perou C, Olopade OI. Genotype-phenotype classification of triple negative breast cancers (TNBC) in women of African descent using the PAM50 NanoString platform and genomic data. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-04-05.

Diagnostic accuracy of tru-cut biopsy of breast lumps at University College Hospital, Ibadan

BACKGROUND

Tru-cut needle biopsies form an integral part of Triple assessment of breast cancer and include clinical assessment, mammography and core needle biopsy. No study has been done to evaluate the validity of the procedure in our environment. This study was done to evaluate the validity of core needle biopsies in our centre.

METHOD

A retrospective study of patients with tru-cut needle biopsies of breast lumps and follow-up excisional biopsy or mastectomy done in the Department of Surgery, University College Hospital, Ibadan over a ten year period was done. Fifty one patients who fulfilled the inclusion criteria had their records obtained from the Department of Pathology. The diagnosis was classified into benign and malignant with the excisional biopsy or mastectomy diagnosis used as the gold standard. The sensitivity, specificity and accuracy were calculated and kappa was also done to evaluate the degree of agreement.

RESULTS

A total of 51 cases were included in this study. The average age of the patients was 47 ± 13 years with a range from 19 to 81 years. Thirty of the biopsies (59%) had a definitive diagnosis of malignancy while twenty one (41%) were benign. The overall sensitivity, specificity and accuracy were 86%, 71% and 80.4% respectively. The specificity of malignant biopsies was 68% while benign was 35%. The level of agreement for malignant biopsies was higher than benign biopsies with a kappa of 0.39 for malignant diagnosis as against 0.29 for benign.

CONCLUSION

Tru-cut needle biopsies have a comparable sensitivity and specificity to excisional biopsies. Diagnostic accuracy can be further enhanced with the adoption of image guided biopsies.

Case reports of adult colo-colonic intussusception

BACKGROUND

Adult colo-colonic intussusception is a rare abnormality and it may pose a diagnostic challenge.

OBJECTIVE

To report two cases of adult colo-colonic intussusception with benign lesion as the lead points.

METHODS

The Clinical records of the two patients containing the management details were retrieved and reviewed.

RESULTS

The 1st case was a 60 year old man presenting with a year history of recurrent left abdominal pain a two week history of fullness left upper and lower abdomen. Examination showed an 8cm by 6 cm mass in the left hypochondrium continuing with another 16cm by 8 cm mass spanning the left lumbar and left iliac fossa. Abdominal ultrasound scan showed a huge mixed echogenic mass in the central abdomen spanning the left hypochondriac, left lumber and suprapubic regions. He had exploratory laparotomy which revealed cob-cobonic intussusception involving the ascending colon up to sigmoid colon. He had subtotal colectomy done. The lead point was a hamartomatous polyp The 2nd case was a 35 year old man with a two month history of recurrent abdominal pain and haematochezia, a month history change in bowel habit and five day history of abdominal distension. Examination showed distended abdomen with generalised tenderness. There was a firm mass in the left hypochondrium extending to the left iliac fossa. Abdominal ultrasound scan confirm intussusception: Exploratory laparotomy showed perforation of transverse colon at the neck of cob-colonic intussusception involving the distal third of the transverse colon to the rectum. He had extended left hernicolectomy and Devine colostomy done. He died 36 h6urs post operation. The lead point was an inflammatory polyp.

CONCLUSION

Adult colo-colonic intussusception is an uncommon disease which may not present in a typical feature of intussusception as occur in children thus posing diagnostic dilemma. High index of suspicion with radiological investigation will serve to aid rapid and accurate diagnosis.

Abstract B11: Replication of previously identified breast cancer susceptibility loci in a breast cancer case-control study on women of African ancestry

To date, more than 100 single nucleotide polymorphisms (SNPs) have been found to be associated with breast cancer susceptibility in large genome-wide association studies (GWAS) conducted predominantly in women of European and Asian ancestries. To identify breast cancer susceptibility alleles in populations of African ancestry, we performed a GWAS in 3,686 subjects from Nigeria, Barbados and the United States (Baltimore, Chicago, Detroit, Philadelphia and the Southern Community Cohort Study), using the Illumina HumanOmni2.5 array. Using stringent quality control criteria, a total of 1,657 cases (777 with known estrogen receptor [ER] status) and 2,029 controls were successfully genotyped for 2,116,365 SNPs. Subsequently, imputation was conducted using reference panels from The 1000 Genomes Project and logistic regression models controlling age and global ancestry were applied to examine the association of 78 known breast cancer GWAS index SNPs and 44 iCOGS (Illumina iSelect genotyping array for Collaborative Oncological Gene-Environment Study) SNPs with breast cancer risk in our study population. Only 4 SNPs were statistically significant (unadjusted P&lt;0.01) associated with breast cancer in women of African descent: rs3112612 (16q12.1, P=0.0021), rs3817198 (11p15.5, P=0.0049), rs10069690 (5p15.33, P=0.0056), and rs1978503 (18q21.2, P=0.0066). Additional five SNPs were found to be associated with breast cancer at the unadjusted P&lt;0.05 significance level: rs458685 (12q21.3), rs361147 (4q31.3), rs4322600 (14q31.3), rs616488 (1p36.22), and rs17356907 (12q22). We also observed positive associations for ER-negative breast cancer: rs3817198 (11p15.5, P=0.0029), rs6762644 (3p26.1, P=0.0036), rs10069690 (5p15.33, P=0.0048), and rs3803662 (16q12.1, P=0.0050); and ER-positive breast cancer: rs12355688 (10q22.3, P=0.011), rs1978503 (18q21.2, P=0.020), rs3112612 (16q12.1, P=0.032), and rs4784227 (16q12.1, P=0.038). In conclusion, our observations highlight the necessity of validating previous breast cancer GWAS findings across diverse populations. Different environmental factors, allele frequencies and linkage disequilibrium patterns may influence the genetic risk profiles in different populations. Larger genetic studies in women of African ancestry hold promise to reveal additional risk variants for developing polygenic risk models for breast cancer susceptibility in this population.

Citation Format: Yonglan Zheng, Dezheng Huo, Temidayo O. Ogundiran, Adeyinka G. Falusi, Oladosu Ojengbede, Clement Adebamowo, William J. Blot, Wei Zheng, Qiuyin Cai, Lisa B. Signorello, Katherine L. Nathanson, Susan M. Domchek, Timothy R. Rebbeck, Michael S. Simon, Anselm J.M. Hennis, Barbara Nemesure, Suh-Yuh Wu, Maria Cristina Leske, Stefan Ambs, Abayomi Odetunde, Imaria Anetor, Stella Akinleye, Qun Niu, Jing Zhang, Anna Pluzhnikov, Anuar Konkashbaev, Lin Chen, Eric R. Gamazon, Younghee Lee, Nancy J. Cox, Olufunmilayo O. Olopade. Replication of previously identified breast cancer susceptibility loci in a breast cancer case-control study on women of African ancestry. [abstract]. In: Proceedings of the Sixth AACR Conference: The Science of Cancer Health Disparities; Dec 6–9, 2013; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2014;23(11 Suppl):Abstract nr B11. doi:10.1158/1538-7755.DISP13-B11

Bone Scintigraphy in Breast Cancer Patients in Ibadan, Nigeria

BACKGROUND

The bone is the commonest site of metastases from breast carcinoma. Radionuclide isotope scanning is a sensitive scanning procedure for the demonstration of bone pathology. In May 2006, a gamma camera was introduced into clinical use for skeletal scintigraphy at the University College Hospital, Ibadan, Nigeria.

OBJECTIVE

To review the first five years findings of skeletal scintigraphy in our breast cancer patients.

METHODS

We retrospectively reviewed the clinical data and scintigraphic bone studies of patients with histology proven breast carcinoma managed in the Surgical Oncology Division, University College Hospital, Ibadan, Nigeria between May 2006 and April 2011.

RESULTS

Within the period, a total of 597 breast cancer patients had skeletal scintigraphy (SS). Of the 594 (99.5%) SS reports available for review, scintigraphic evidence of bone metastases was found in 232 (39.1%) patients. Correlation of bone involvement and clinical stage showed that a large majority of the patients had stage IV (83.3%) and III (15.7%) disease. Most patients (71.6%) had multiple bone lesions. The bone lesions were osteoblastic in 88.9% of the patients; only 1.8% had purely osteolytic lesions with the remainder being a mix of both.

CONCLUSION

There was scintigraphic evidence of bone metastasis in most of our patients with stage four breast cancer and in some with locally advanced disease. Multiple bone lesions were found in many of them and almost all the lesions were osteoblastic. Moreover, both the truncal and axial skeletal bones were involved in similar proportions.

Voluntary participation and comprehension of informed consent in a genetic epidemiological study of breast cancer in Nigeria

BACKGROUND

Studies on informed consent to medical research conducted in low or middle-income settings have increased, including empirical investigations of consent to genetic research. We investigated voluntary participation and comprehension of informed consent among women involved in a genetic epidemiological study on breast cancer in an urban setting of Nigeria comparing women in the case and control groups.

METHODS

Surveys were administered in face-to-face interviews with 215 participants following their enrollment in the genetic study (106 patients, 109 controls). Audio-taped in-depth interviews were conducted with a sub-sample of 17 (8%) women who completed the survey.

RESULTS

The majority of all participants reported being told that participation in the genetic study was voluntary (97%), that they did not feel pressured to participate in the study (99%), and that they could withdraw from the study (81%). The majority of the breast cancer patients (83%) compared to 58% of women in the control group reported that the study purpose was to learn about the genetic inheritance of breast cancer (OR 3.44; 95% CI =1.66, 7.14, p value = 0.001). Most participants reported being told about study procedures (95%) and study benefits (98%). Sixty-eight percent of the patients, compared to 47% of the control group reported being told about study risks (p-value <0.001). Of the 165 married women, 19% reported asking permission from their husbands to enroll in the breast cancer study; no one sought permission from local elders. In-depth interviews highlight the use of persuasion and negotiation between a wife and her husband regarding study participation.

CONCLUSIONS

The global expansion of genetic and genomic research highlights our need to understand informed consent practices for studies in ethnically diverse cultural environments such as Africa. Quantitative and qualitative empirical investigations of the informed consent process for genetic and genomic research will further our knowledge of complex issues associated with communication of information, comprehension, decisional authority and voluntary participation. In the future, the development and testing of innovative strategies to promote voluntary participation and comprehension of the goals of genomic research will contribute to our understanding of strategies that enhance the consent process.

Mastectomy for management of breast cancer in Ibadan, Nigeria

Background

Modified radical mastectomy remains the standard therapeutic surgical operation for breast cancer in most parts of the world. This retrospective study reviews mastectomy for management of breast cancer in a surgical oncology division over a ten year period.

Methods

We reviewed the case records of consecutive breast cancer patients who underwent mastectomy at the Surgical Oncology Division, University College Hospital (UCH) Ibadan between November 1999 and October 2009.

Results

Of the 1226 newly diagnosed breast cancer patients over the study period, 431 (35.2%) patients underwent mastectomy making an average of 43 mastectomies per year. Most patients were young women, premenopausal, had invasive ductal carcinoma and underwent modified radical mastectomy as the definitive surgical treatment. Prior to mastectomy, locally advanced tumors were down staged in about half of the patients that received neo-adjuvant combination chemotherapy. Surgical complication rate was low. The most frequent operative complication was seroma collection in six percent of patients. The average hospital stay was ten days and most patients were followed up at the surgical outpatients department for about two years post-surgery.

Conclusions

There was low rate of mastectomy in this cohort which could partly be attributable to late presentation of many patients with inoperable local or metastatic tumors necessitating only palliative or terminal care. Tumor down-staging with neo-adjuvant chemotherapy enhanced surgical loco-regional tumor control in some patients. The overall morbidity and the rates of postoperative events were minimal. Long-term post-operative out-patients follow-up was not achieved as many patients were lost to follow up after two years of mastectomy.

Neo-adjuvant capecitabine chemotherapy in women with newly diagnosed locally advanced breast cancer in a resource-poor setting (Nigeria): efficacy and safety in a phase II feasibility study

The majority of clinical trials of neo-adjuvant therapy for breast cancer have been conducted in resource-rich countries. We chose Nigeria, a resource-poor country, as the major site for a phase II feasibility open-label multicenter clinical trial designed to evaluate the efficacy, safety, and tolerability of neo-adjuvant capecitabine in locally advanced breast cancer (LABC). Planned treatment consisted of 24 weeks of capecitabine at a dose of 1,000 mg/m(2) twice daily (2,000 mg/m(2) total per day). The primary endpoints were overall, partial, complete clinical response rate (OCR, PCR, CCR) and complete pathologic response (cPR). A total of 16 patients were recruited from August 2007 to April 2010. The study was terminated early as a result of slow accrual. After the first three cycles of therapy, PCR were seen in five of 16 patients (31%; 95% CI 11-59%). Of the remaining 11 patients, eight had no response (NR) or stable disease (SD), and three had progressive disease (PD). Seven patients proceeded with further therapy of which had SD. OCR at the end of eight cycles was 44% (95% CI 20-70%). Clinical response and radiologic response by ultrasonomammography were highly concordant (spearman correlation 0.70). The most common adverse effect was Grade 1 hand-foot syndrome, which was seen in 75% of patients. Despite several limitations, we successfully carried out this phase II feasibility study of neo-adjuvant capecitabine for LABC in Nigeria. Capecitabine monotherapy showed good overall response rates with minimal toxicity and further studies are warranted.

Fine mapping of breast cancer genome-wide association studies loci in women of African ancestry identifies novel susceptibility markers

Numerous single nucleotide polymorphisms (SNPs) associated with breast cancer susceptibility have been identified by genome-wide association studies (GWAS). However, these SNPs were primarily discovered and validated in women of European and Asian ancestry. Because linkage disequilibrium is ancestry-dependent and heterogeneous among racial/ethnic populations, we evaluated common genetic variants at 22 GWAS-identified breast cancer susceptibility loci in a pooled sample of 1502 breast cancer cases and 1378 controls of African ancestry. None of the 22 GWAS index SNPs could be validated, challenging the direct generalizability of breast cancer risk variants identified in Caucasians or Asians to other populations. Novel breast cancer risk variants for women of African ancestry were identified in regions including 5p12 (odds ratio [OR] = 1.40, 95% confidence interval [CI] = 1.11-1.76; P = 0.004), 5q11.2 (OR = 1.22, 95% CI = 1.09-1.36; P = 0.00053) and 10p15.1 (OR = 1.22, 95% CI = 1.08-1.38; P = 0.0015). We also found positive association signals in three regions (6q25.1, 10q26.13 and 16q12.1-q12.2) previously confirmed by fine mapping in women of African ancestry. In addition, polygenic model indicated that eight best markers in this study, compared with 22 GWAS-identified SNPs, could better predict breast cancer risk in women of African ancestry (per-allele OR = 1.21, 95% CI = 1.16-1.27; P = 9.7 × 10(-16)). Our results demonstrate that fine mapping is a powerful approach to better characterize the breast cancer risk alleles in diverse populations. Future studies and new GWAS in women of African ancestry hold promise to discover additional variants for breast cancer susceptibility with clinical implications throughout the African diaspora.

Development and pilot testing of an online module for ethics education based on the Nigerian National Code for Health Research Ethics

BACKGROUND

The formulation and implementation of national ethical regulations to protect research participants is fundamental to ethical conduct of research. Ethics education and capacity are inadequate in developing African countries. This study was designed to develop a module for online training in research ethics based on the Nigerian National Code of Health Research Ethics and assess its ease of use and reliability among biomedical researchers in Nigeria.

METHODOLOGY

This was a three-phased evaluation study. Phase one involved development of an online training module based on the Nigerian Code of Health Research Ethics (NCHRE) and uploading it to the Collaborative Institutional Training Initiative (CITI) website while the second phase entailed the evaluation of the module for comprehensibility, readability and ease of use by 45 Nigerian biomedical researchers. The third phase involved modification and re-evaluation of the module by 30 Nigerian biomedical researchers and determination of test-retest reliability of the module using Cronbach's alpha.

RESULTS

The online module was easily accessible and comprehensible to 95% of study participants. There were significant differences in the pretest and posttest scores of study participants during the evaluation of the online module (p = 0.001) with correlation coefficients of 0.9 and 0.8 for the pretest and posttest scores respectively. The module also demonstrated excellent test-retest reliability and internal consistency as shown by Cronbach's alpha coefficients of 0.92 and 0.84 for the pretest and posttest respectively.

CONCLUSION

The module based on the Nigerian Code was developed, tested and made available online as a valuable tool for training in cultural and societal relevant ethical principles to orient national and international biomedical researchers working in Nigeria. It would complement other general research ethics and Good Clinical Practice modules. Participants suggested that awareness of the online module should be increased through seminars, advertisement on government websites and portals used by Nigerian biomedical researchers, and incorporation of the Code into the undergraduate medical training curriculum.

Office based muscle biopsy using Vacora vacuum assisted biopsy system

INTRODUCTION

Muscle biopsy is a minor surgical procedure that has been conducted over several decades in clinical practice. Over the years, the technique to implement this procedure has been modified to make it easier to perform and more tolerable for the patient. This study aimed to assess the feasibility of muscle biopsy as an office based procedure, by using a vacuum Assisted Biopsy System.

METHOD

The procedure was successfully carried out on 57 individuals with/without diabetes, currently involved in the African American Diabetes Mellitus Study. One specimen was collected percutaneously from the vastus lateralis, under local anesthesia. A 16-gauge needle was used.

RESULTS

Muscle biopsies were successfully carried out on all study participants. The study participants reported no complications after the procedure.

CONCLUSION

The findings from our study show that muscle biopsy can be feasibly implemented as an office based procedure, involving minimal muscle invasion, less trauma, hospital stay time, and expenses.

Recurrent BRCA1 and BRCA2 mutations in breast cancer patients of African ancestry

Recurrent mutations constituted nearly three quarters of all BRCA1 mutations and almost half of all BRCA2 mutations identified in the first cohort of the Nigerian Breast Cancer Study. To further characterize breast/ovarian cancer risks associated with BRCA1/BRCA2 mutations in the African diaspora, we genotyped recurrent mutations among Nigerian, African American, and Barbadian breast cancer patients. A replication cohort of 356 Nigerian breast cancer patients was genotyped for 12 recurrent BRCA1/2 mutant alleles (Y101X, 1742insG, 4241delTG, M1775R, 4359insC, C64Y, 1623delTTAAA, Q1090X, and 943ins10 from BRCA1, and 1538delAAGA, 2630del11, and 9045delGAAA from BRCA2) by means of SNaPshot followed by direct sequencing or by direct sequencing alone. In addition, 260 African Americans and 118 Barbadians were genotyped for six of the recurrent BRCA1 mutations by SNaPshot assay. Of all the BRCA1/2 recurrent mutations we identified in the first cohort, six were identified in 11 patients in the replication study. These mutation carriers constitute 3.1 % [95 % Confidence Interval (CI) 1.6-5.5 %] of the replication cohort. By comparison, 6.9 % (95 % CI 4.7-9.7 %) of the discovery cohort carried BRCA1/2 recurrent mutations. For the subset of recurrent mutations we tested in breast cancer cases from Barbados or the United States, only two 943ins10 carriers were identified in African Americans. Nigerian breast cancer patients from Ibadan carry a broad and unique spectrum of BRCA1/2 mutations. Our data suggest that BRCA1/2 mutation testing limited to recurrent mutations is not sufficient to understand the BRCA1/2-associated breast cancer risk in African populations in the diaspora. As the cost of Sanger sequencing is considerably reduced, deploying innovative technologies such as high throughput DNA sequencing of BRCA1/2 and other cancer susceptibility genes will be essential for identifying high-risk individuals and families to reduce the burden of aggressive early onset breast cancer in low-resource settings.

Neoadjuvant capecitabine chemotherapy in women with newly diagnosed locally advanced breast cancer in a resource-poor setting (Nigeria): Efficacy and safety in a phase II feasibility study

e11554

Background: The majority of clinical trials of neoadjuvant therapy for breast cancer have been conducted in resource-rich countries. We chose Nigeria, a resource-poor country, as the major site for a phase II feasibility open label multicenter clinical trial designed to evaluate the efficacy, safety and tolerability of neoadjuvant capecitabine in locally advanced breast cancer. Methods: Planned treatment consisted of 24 weeks of capecitabine at a dose of 1000mg/m2 twice daily (2000mg/m2 total per day). Each cycle consisted of a 14-day period of therapy followed by a 7-day pause, and patients were evaluated after 3 cycles and taken off study if no response was documented. Responding patients were treated for no more than 8 cycles. The primary endpoints were partial, complete clinical response and pathologic complete response. Results: A total of 16 patients were recruited from August 2007 to April 2010. The study was terminated early as a result of slow accrual. After the first 3 cycles of therapy, partial clinical responses were seen in 5 of 16 patients (31%; 95% CI 11% - 59%). Of the remaining 11 patients, 8 had no response or stable disease, and 3 had progressive disease. Seven pateints proceeded with further therapy, two of them with stable disease but exactly in the border line of 25% increase. By physical examination, only 2 of the 6 patients had a documented complete clinical response, while by ultrasonomammography, partial responses were observed in 5 patients. Thus, overall response rate at the end of 8 cycles were 31.1% both by clinical examination and by ultrasonomammography. Clinical response by physical examination and radiologic response by ultrasonomammography were highly concordant (the spearman correlation between the two ratios was 0.70). The most common adverse effect was Grade 1 Hand and Foot Syndrome in 75% of patients. Conclusions: Despite several limitations, we successfully carried out this phase II feasibility study of neoadjuvant capecitabine for locally advanced breast cancer in Nigeria. Capecitabine monotherapy showed good overall response rates with minimal toxicity and further studies are warranted.

Abstract 2606: Absence of association between common genetic polymorphisms in the TERT-CLPTM1L locus and breast cancer risk in women of African descent

Recent genome wide association studies (GWAS) provided evidence that common low-penetrance single nucleotide polymorphisms (SNPs) contribute to breast cancer development. Common SNPs in the TERT (telomerase reverse transcriptase)-CLPTM1L (cleft lip and palate transmembrane 1 like) locus have been reported to be associated with several types of cancer, such as lung cancer/adenocarcinoma, glioma, bladder cancer, prostate cancer, and pancreatic cancer. Researchers also hypothesized that common SNPs in the TERT gene could play a role in breast cancer susceptibility. However, findings are inconsistent, and most studies included Caucasians only. In the present study, we sought to investigate whether common genetic variants in the TERT-CLPTM1L locus could contribute to breast cancer susceptibility in women of African ancestry. A total 2,892 women of African ancestry were participated in the present study, consisting of 1,509 breast cancer cases and 1,383 controls collected from Nigeria, Barbados, and the United States. Eleven SNPs in the TERT-CLPTM1L locus that were previously shown to be associated with cancers were selected and genotyped using the Illumina GoldenGate Genotyping platform, together with 30 ancestry informative markers (AIMs). Test for HWE suggested that the genotypes for all the SNPs were in Hardy-Weinberg proportions and there was no deviation from HWE. We performed unconditional multiple logistic regression to estimate the association between the TERT-CLPTM1L genetic variants and breast cancer risk, adjusting for age, study site, and estimated genetic ancestry. Overall we did not observe any P value &lt; 0.05 after permutation in the analyses of allelic and genotypic models. We also conducted haplotype analysis for a five-SNP LD block, rs4975616-rs3816659-rs402710-rs401681-rs31489 but again failed to obtain significant association in the present study. Our findings do not support an effect of the tested genetic variants in the TERT-CLPTM1L locus on breast cancer susceptibility in women of African ancestry. However, it is worth noting that our current study did not apply a fine-mapping strategy; other genetic variants in LD with previously reported cancer susceptibility polymorphisms might be bona fide causal variants contributing to the risk of breast cancer. Larger independent studies from diverse populations are expected to evaluate the importance of the TERT-CLPTM1L locus in breast cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2606. doi:1538-7445.AM2012-2606

Body fat distribution and breast cancer risk: findings from the Nigerian breast cancer study

PURPOSE

The relationship between overall obesity and breast cancer risk has been well recognized, but the role of central obesity in breast cancer development is uncertain.

METHODS

Between 1998 and 2009, 1,233 invasive breast cancer cases and 1,101 community controls were recruited into the Nigerian Breast Cancer Study at Ibadan, Nigeria. Logistic regressions were used to calculate multivariate odds ratio (OR) and 95% confidence intervals (CI), adjusting for age, body mass index (BMI), and other known risk factors for breast cancer.

RESULTS

The OR for the highest quartile group of waist circumference relative to the lowest was 2.39 (95% CI, 1.59-3.60; P-trend < 0.001). Comparing women with waist/hip ratio (WHR) in the lowest quartile group, the OR for women in the highest quartile category was 2.15 (95% CI, 1.61-2.85; P-trend < 0.001). An inverse association was observed between hip circumference and breast cancer, with an OR of 0.36 for the highest quartile (95% CI, 0.24-0.55; P-trend < 0.001). The effects of these three measures existed in both pre- and postmenopausal women. Of note, we found a significant interaction between WHR and BMI (P-interaction = 0.016): the OR comparing the highest to the lowest WHR quartile was 2.81 (95% CI, 1.90-4.16) for women with BMI < 25 kg/m2 and 1.70 (95% CI, 1.11-2.61) for women with BMI ≥ 25 kg/m2.

CONCLUSIONS

These results suggest that central adiposity, measured by waist circumference and waist/hip ratio, was an important risk factor for breast cancer in Nigerian women, and the effect of central adiposity was strong in normal-weight women.

Evaluation of 19 susceptibility loci of breast cancer in women of African ancestry

Multiple breast cancer susceptibility loci have been identified in genome-wide association studies (GWAS) in populations of European and Asian ancestry using array chips optimized for populations of European ancestry. It is important to examine whether these loci are associated with breast cancer risk in women of African ancestry. We evaluated 25 single nucleotide polymorphisms (SNPs) at 19 loci in a pooled case-control study of breast cancer, which included 1509 cases and 1383 controls. Cases and controls were enrolled in Nigeria, Barbados and the USA; all women were of African ancestry. We found significant associations for three SNPs, which were in the same direction and of similar magnitude as those reported in previous fine-mapping studies in women of African ancestry. The allelic odds ratios were 1.24 [95% confidence interval (CI): 1.04-1.47; P = 0.018] for the rs2981578-G allele (10q26/FGFR2), 1.34 (95% CI: 1.10-1.63; P = 0.0035) for the rs9397435-G allele (6q25) and 1.12 (95% CI: 1.00-1.25; P = 0.04) for the rs3104793-C allele (16q12). Although a significant association was observed for an additional index SNP (rs3817198), it was in the opposite direction to prior GWAS studies. In conclusion, this study highlights the complexity of applying current GWAS findings across racial/ethnic groups, as none of GWAS-identified index SNPs could be replicated in women of African ancestry. Further fine-mapping studies in women of African ancestry will be needed to reveal additional and causal variants for breast cancer.

Genetic susceptibility to type 2 diabetes and breast cancer risk in women of European and African ancestry

BACKGROUND

Epidemiologic studies have reported a positive association between type 2 diabetes (T2D) and breast cancer risk, independent of body weight.

METHODS

We investigated 40 genetic variants known to be associated with T2D in relation to breast cancer risk among 2,651 breast cancer cases and 2,520 controls of African or European ancestry that were pooled from seven studies.

RESULTS

We found that two T2D risk alleles in Caucasian women (rs5945326-G, rs12518099-C) and one in women of African ancestry (rs7578597-T) were positively associated with breast cancer risk at a nominal significance level of 0.05, whereas two T2D risk alleles were inversely associated with breast cancer risk in Caucasian women (rs1111875-C, rs10923931-T). The composite T2D susceptibility score (the number of risk allele) was not significantly associated with breast cancer risk.

CONCLUSION

The association between established T2D genetic susceptibility variants and breast cancer risk in women of African or European ancestry is likely weak, if it does exist.

IMPACT

The pleiotropic effects of known T2D risk alleles cannot explain the association between T2D and breast cancer risk.

Surgeon-patient information disclosure practices in southwestern Nigeria

OBJECTIVE

This study examined the practice of information disclosure to patients by surgeons in Nigeria.

SUBJECTS AND METHODS

A 55-item self-administered semi-structured questionnaire was sent to 150 surgeons in southwestern Nigeria in 2004-2005. The data obtained from the completed questionnaire were analyzed using descriptive statistics.

RESULTS

Of the 150 surgeons, 102 completed the questionnaire, giving a response rate of 68.0%. Of these 102, 85 (85.3%) were men, 44 (43.1%) were consultants and 55 (54.0%) were senior and junior surgical trainees. Most were from surgical subspecialties and obstetrics and gynecology. A documented policy statement about information disclosure was not available in most hospitals. A third, i.e. 35 (34.3%), of the surgeons did not routinely engage patients in discussions about disease diagnosis, management and prognosis. Most, i.e. 73 (71.6%), would rather disclose worsening disease progression to the patient's spouse. Others would disclose such information to the patient's children, family members or clergy. This was presumably to shield the patient from psychological distress. Only 22 (21.6%) of them routinely disclose operative findings to patients or their families. Thirty (29.4%) of them had been involved in disclosing medical errors to their patients in the past while 63 (61.8%) respondents did not know if surgical errors with potentially negative consequences should be disclosed.

CONCLUSION

Most of the surgeons in southwestern Nigeria did not routinely provide detailed information to patients about their illness and possible outcome of illness even in the presence of worsening disease progression and prognosis. When surgical errors with potential negative consequences occurred, the majority did not know if such errors should be disclosed.

Lack of association between common single nucleotide polymorphisms in the TERT-CLPTM1L locus and breast cancer in women of African ancestry

As one of the most common cancers worldwide, breast cancer places an extraordinary burden on the populations of African ancestry. Common SNPs in the TERT-CLPTM1L locus have been reported to be associated with several types of cancer, including breast cancer. We sought to investigate whether the previously reported common single nucleotide polymorphisms (SNPs) in the TERT-CLPTM1L locus could also contribute to the breast cancer risk in women of African ancestry. We genotyped eleven SNPs in 2,892 women of African descent but were unable to detect any significant association between TERT-CLPTM1L SNPs and their predispositions for breast cancer risk. Given the differences in linkage disequilibrium patterns across populations, our findings suggest that larger independent studies from diverse populations are expected to evaluate the importance of the TERT-CLPTM1L locus in breast cancer.

Abstract 3734: Alcohol consumption and breast cancer risk among Nigerian women

Background: Alcohol consumption has been reported as a risk factor for breast cancer. However, little is known about its importance for indigenous African population, among whom the prevalence of breast cancer is relatively low. The purpose of this study was to investigate the relationship between alcohol drinking and breast cancer risk in Nigerian women.

Methods: The study was based on the Nigerian Breast Cancer Study, a case-control study of breast cancer conducted in Ibadan, Nigeria, between 1998 and 2010. In-person interviews were conducted with 1355 invasive breast cancer cases and 1132 community controls, using structured questionnaires to collect detailed epidemiologic data including alcohol drinking. Multivariate logistic regression was performed to estimate odds ratios (OR) and 95% confidence intervals (CI), controlling for age, ethnicity, and type of questionnaire (we revised the questionnaire in the middle of study), with potential effect measure modifications tested.

Results: 5.8% controls and 11.3% cases reported drinking alcohol every week for at least 6 months, with crude OR=2.08 (95% CI: 1.54-2.82, p&lt;0.0001). After adjusting for potential confounding variables, alcohol drinking remained statistically associated with breast cancer risk but the strength of association was attenuated (adjusted OR=1.56, 95% CI: 1.11-2.19, p=0.01). Among women who drink weekly, the average drinks per week were 1.7±0.8 in controls and 3.4±5.8 in cases, and there was a dose-response trend: the crude OR was 1.86 for women who had 1-2 drinks per week and 3.27 for those who had ≥ 2 drinks per week, compared with non-drinkers (p-trend=0.08). The age- and ethnicity-adjusted ORs for 1-2 drinks and ≥ 2 drinks per week were 1.20 (95% CI: 0.49-2.93) and 1.80 (95% CI: 0.36-8.87), respectively. The association between alcohol drinking and breast cancer was particularly stronger in overweight or obese women who have BMI ≥ 25 kg/m2 (adjusted OR=1.92, 95% CI: 1.23-3.01, p=0.004) than in normal weight women (adjusted OR=1.20, 95% CI: 0.71-2.02, p=0.5). Similar association was observed in pre-menopausal and post-menopausal women.

Conclusions: Our study showed that regular alcohol intake is uncommon among Nigerian women. However, regular alcohol drinking may increase breast cancer risk among the Nigerians, particularly overweight women.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3734. doi:10.1158/1538-7445.AM2011-3734

Abstract LB-425: Replication of 18 susceptibility loci of breast cancer in women of African ancestry

Background: Numerous novel susceptibility loci for breast cancer have been identified in genome-wide association studies (GWAS). However, all GWAS of breast cancer have been conducted in populations of European and Asian ancestry and array chips optimized for populations of European ancestry have been used. Thus the question remains whether these genetic associations can be generalized more broadly to other racial/ethnic populations. We addressed this question and examined whether common genetic variants identified from prior GWAS are associated with breast cancer risk in women of African ancestry.

Methods: We evaluated 24 single nucleotide polymorphisms (SNPs) at 1p11, 2q35, 3p24, 5p12, 5q11, 6q22, 6q25, 8q24, 9p21, 10q21, 10q22, 10q26, 11p15, 11q13, 14q24, 16q12, 17q23, and 19p13, in a pooled case-control study of breast cancer, which included 1,543 cases and 1,416 controls. Cases and controls were enrolled in Nigeria, Barbados, and the United States; all were women of African ancestry by self-report. We also selected 30 ancestral informative markers to estimate and control for population admixture in African Americans and African Barbadians. Logistic regression models were used to estimate odds ratio and 95% confidence intervals (CI) for each SNP, after adjusting for study sites and proportion of European admixture.

Results: The mean age (SD) was 47.9 years old (12.1) in cases and 47.0 years old (13.2) in controls; the majority of cases (58.8%) and controls (58.2%) were younger than age 50. The proportion of European admixture was 0.143 in Barbadians and 0.218 in African Americans. Cases and controls had similar proportions of European admixture. Significant associations were observed between two index SNPs (rs10995190 at 10q21 and rs3817198 at 11p15) and breast cancer risk, but the associations were in the opposite direction of the previous studies. The minor allele frequencies for both SNPs were different slightly between this and previous studies but no switch between minor and major alleles. For the remaining 16 loci, no significant associations were observed for the index SNPs from GWAS. We also evaluated two SNPs identified from previous fine-mapping studies in women of African ancestry. We found both SNPs were significantly associated with breast cancer risk in the present study. The allelic odds ratio was 1.24 (95% CI: 1.04-1.47; p=0.018) for the rs2981578-G allele (10q26/FGFR2) and 1.34 (95% CI: 1.10-1.63; p=0.0035) for the rs9397435-G allele (6q25).

Conclusion: This study highlights the complexity of applying current GWAS findings across racial/ethnic groups, as none of GWAS-identified index SNPs could be replicated in women of African ancestry. Our successful replication of SNPs from fine-mapping studies suggests that fine-mapping studies and new GWAS in understudied minority population may be promising to reveal additional and causal variants for breast cancer susceptibility.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-425. doi:10.1158/1538-7445.AM2011-LB-425

Surgeons' opinions and practice of informed consent in Nigeria

BACKGROUND

Informed consent is perhaps more relevant to surgical specialties than to other clinical disciplines. Fundamental to this concept is the provision of relevant information for the patient to make an informed choice about a surgical intervention. The opinions of surgeons in Nigeria about informed consent in their practice were surveyed.

METHODS

A cross-sectional survey of surgeons in Nigeria was undertaken in 2004/5 using self-administered semistructured questionnaires.

RESULTS

There were 102 respondents, 85.3% of whom were men and 58.8% were aged 31-40&emsp14;years. 43.1% were consultants and 54.0% were surgical trainees. 27.4% were in surgical subspecialties, 26.5% in general surgery and 21.6% were obstetricians and gynaecologists. 54.9% agreed that sufficient information is not provided to patients while obtaining their consent for surgical procedures. They listed medicolegal reasons (70.6%), informing patients about benefits, risks and alternatives (64.7%) and hospital policy (50.0%) as some reasons for obtaining consent for surgical procedures. When patients decline to give consent for surgery, 84.3% of them thought that poor communication between surgeons and patients may be contributory. They identified taking a course in bioethics during surgical training and compulsory communication skills course as some ways to improve communication between surgeons and patients.

CONCLUSION

Most Nigerian surgeons seemed to have a good knowledge of the informed consent requirements and process but fall short in practice. There is a need to improve the surgeon-patient relationship in line with modern exigencies to provide interactive environments for fruitful patient communication and involvement.

Case-control study of body size and breast cancer risk in Nigerian women

Previous studies have shown that weight is inversely associated with premenopausal breast cancer and positively associated with postmenopausal disease. Height has been shown to be positively correlated with breast cancer risk, but the association was not conclusive for premenopausal women. These previous studies were conducted primarily in Western countries, where height is not limited by nutritional status during childhood. The authors assessed the association between breast cancer and anthropometric measures in the Nigerian Breast Cancer Study (Ibadan, Nigeria). Between 1998 and 2009, 1,233 invasive breast cancer cases and 1,101 controls were recruited. The multivariate-adjusted odds ratio for the highest quartile group of height relative to the lowest was 2.03 (95% confidence interval (CI): 1.51, 2.72; P-trend < 0.001), with an odds ratio of 1.22 (95% CI: 1.14, 1.32) for each 5-cm increase, with no difference by menopausal status. Comparing women with a body mass index in the lowest quartile group, the adjusted odds ratio for women in the highest quartile category was 0.72 (95% CI: 0.54, 0.94; P-trend = 0.009) for premenopausal and postmenopausal women. Influence of height on breast cancer risk was quite strong in this cohort of indigenous Africans, which suggests that energy intake during childhood may be important in breast cancer development.

Review of fine needle aspiration cytology in the management of goitres in Ibadan, Nigeria

OBJECTIVE

The use of Fine Needle Aspiration Cytology (FNAC) in the investigation of goitres was introduced into our practice more than a decade ago. This is a review of its diagnostic accuracy for thyroid carcinoma seven years after the first evaluation and following the establishment of the 'FNAC Clinic'.

METHOD

This is a retrospective study of patients who had FNAC of goitres and the histopathology of their thyroidectomy specimens between 1995 and 2004. The accuracy of the cytology reports were evaluated against the histology reports. The turnaround time of the patients for surgery was also determined.

RESULTS

There were 130 females and 21 males with an age range of 7-86 years. The diagnostic accuracy of the procedure for carcinoma was 89% with a sensitivity of 35%, specificity of 97%, positive predictive value of 64%, and a negative predictive value of 91%. The average turnaround time for surgery was 178.7 +/- 248.7 days with a range of five days to three and a half years.

CONCLUSION

The diagnostic accuracy of FNAC of goitre for carcinoma improved in the period under review. However, the long surgery turnaround time may reduce the usefulness of the procedure. The accuracy may be improved further by a protocol of ultrasound guidance, capillary collection with no-aspiration technique, on-site review of slides with a repeat of FNA as necessary.

Bioethics in the medical curriculum in Africa

Many new innovations and advances are introduced into life and the sciences at a pace faster than any single individual can keep up with but human beings adjust to these changes at a much slower pace. Development is at snail speed in many developing countries and supersonic in the developed world and yet these have to interrelate. The introduction of medical technology and advances into developing countries is sometimes done haphazardly and often without prior appropriate education and decision making process. This has the potential to create dilemmas among stakeholders and engender conflicts with culture, religion and societal norms. A good grounding in the study of bioethical principles and theories is relevant to addressing current and evolving issues with changing biotechnology and shifting landmarks in today's highly technical clinical medicine. The knowledge and utilization of these principles should limit the occurrence of many scandals in the form and magnitude already recorded in the history of biomedical research and practice. While the debate as to whether ethics can be taught will continue, bioethics education provides the requisite knowledge and skill that are applicable at the bedside and in biomedical research. Some evidence has shown that formal teaching of ethics impacts positively on physicians and medical students' attitudes in the care of patients. In this paper we propose that bioethics as a distinct course should be incorporated into medical curriculum in Africa. The integration of bioethics as a required subject in the medical curriculum would have a positive impact on all aspects of health care and research. Real or assumed obstacles are not justifiable reasons for further delay in implementing this initiative

Parity and breastfeeding are protective against breast cancer in Nigerian women

As the relation between reproductive factors and breast cancer risk has not been systematically studied in indigenous women of sub-Saharan Africa, we examined this in a case–control study in Nigeria. In-person interviews were conducted using structured questionnaires to collect detailed reproductive history in 819 breast cancer cases and 569 community controls between 1998 and 2006. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CI). Compared with women with menarcheal age <17 years, the adjusted OR for women with menarcheal age ⩾17 years was 0.72 (95% CI: 0.54–0.95, P=0.02). Parity was negatively associated with risk (P-trend=0.02) but age at first live birth was not significant (P=0.16). Importantly, breast cancer risk decreased by 7% for every 12 months of breastfeeding (P-trend=0.005). It is worth noting that the distribution of reproductive risk factors changed significantly from early to late birth cohorts in the direction of increasing breast cancer incidence. Our findings also highlight the heterogeneity of breast cancer aetiology across populations, and indicate the need for further studies among indigenous sub-Saharan women.

Genetic polymorphisms in uridine diphospho-glucuronosyltransferase 1A1 and breast cancer risk in Africans

The UDP-glucuronosylatransferase 1A1 (UGT1A1) gene is involved in the metabolism of estrogen and detoxification of potential carcinogens. The number of TA repeats in the promoter region of UGT1A1 has been linked to breast cancer risk, but results varied by race. We performed a comprehensive assessment of genetic polymorphisms in the UGT1A1 gene, and examined these polymorphisms and TA repeats in relation to breast cancer risk in a case-control study in Nigeria. 512 breast cancer cases and 226 community controls were genotyped for UGT1A1. Compared with high-activity TA repeat genotypes, the odds ratios (OR) for low-activity and moderate-activity genotypes were 0.47 (95% confidence interval CI, 0.26-0.83) and 0.64 (95% CI, 0.39-1.06), respectively, in premenopausal women (P = 0.009 for trend), but no association was observed in postmenopausal women (P = 0.24). The effect of TA repeats was also differentiated by age: the OR was 0.39 (95% CI 0.21-0.71) for low-activity genotypes and 0.58 (95% CI 0.33-1.00) for moderate-activity genotypes in women <45 years old (P = 0.002 for trend), but no association was observed in women >or=45 years old (P = 0.15). Haplotype analysis showed that UGT1A1 haplotypes were highly diverse with blocked structures. We found a specific haplotype in block 2 that was significantly associated with a 2.1-fold elevated risk (95% CI 1.05-4.39; P = 0.04). In contrast with previous studies, we found low-activity TA repeat alleles were protective against breast cancer among premenopausal indigenous Africans, suggesting that the role of UGT1A1 in breast cancer development may vary by population, presumably due to different environmental and genetic modifier effects.

Immunohistochemical and molecular subtypes of breast cancer in Nigeria

OBJECTIVE

Previous studies suggest that the majority of breast cancer in Africans are hormone receptor negative and thus differ from breast cancer in other populations. We decided to evaluate the hormone receptor status of patients seen in our practice to see if they indeed differ from that of other populations.

METHODS

We prospectively collected and analyzed tumors from consecutive patients presenting to our clinic over an 18 months period from July 2004. During the period, we saw 192 patients without previous histological diagnosis and conducted routine histological and immunohistochemical analysis of their tumors for hormone receptor status.

RESULTS

Most, 65.1% of tumors were ER+, 54.7% were PR+ and 79.7% were HER2 negative. Majority of the tumors, 77.6% were luminal type A, 2.6% were luminal type B, 15.8% were basal type and the remaining 4.0% (6/152) were HER2+/ER- subtype. We found an association between hormone receptor status and tumor grade but not with stage at presentation.

CONCLUSION

We conclude that there is no difference in the pattern of hormone receptors in breast cancer patients of African origin compared to other populations and urge more use of hormone manipulation for management of breast cancer in this population.