Prevalence and Spectrum of Breast Cancer Inherited Mutations in Uganda and Cameroon Women

Background: Breast cancer among indigenous Africans is characterized by higher prevalence of triple-negative disease and poor prognosis. A previous study in Nigeria reported a strikingly high prevalence of deleterious germline mutations in BRCA1 and BRCA2 among Nigerian women with breast cancer. It is unknown if this is true in other sub-Saharan African countries. Aim: The objective of this study is to determine the frequency of germline mutations among an unselected sample of women in Africa. Methods: We conducted a case-control study of breast cancer in Uganda and Cameroon to investigate genetic and nongenetic risk factors for breast cancer. Breast cancer cases were enrolled in two tertiary hospitals in the two countries, unselected for age at diagnosis and family history. Controls who were free of breast cancer were enrolled in the same hospitals and matched to cases on age. A 24-gene sequencing panel was used to test germline mutations in cases and controls. Results: There were 176 cases and 177 controls with a mean age at diagnosis of 46.2 years for cases and mean age at interview of 46.7 years for controls. Among cases, 18.2% carried a pathogenic mutation in a breast cancer gene: 6.3% in BRCA1, 6.3% in BRCA2, 1.7% in ATM, 1.1% in PALB2, 0.6% in BARD1, 0.6% in CDH1, 0.6% in TP53, and 1.2% in any of 17 other genes. Among controls, 2.3% carried a pathogenic mutation in one of the 24 susceptibility genes. Cases were 9.6-fold more likely to carry a mutation compared with controls (odds ratio=9.61, 95% confidence interval: 3.28-38.1; P < 0.001). The mean age of breast cancer cases with pathogenic BRCA1 mutations was 38.3 years compared with 46.7 years among other cases without such mutations ( P = 0.03). There was a trend that cases with a positive family history had higher chance of carrying a mutation (33.3%) than cases without (17.1%), but few cases reported a positive family history. Conclusion: Our findings confirm the earlier report of a high proportion of deleterious mutations in BRCA1 and BRCA2 among breast cancer patients in sub-Saharan Africa. As most of these women present with advanced breast cancer, there is an urgent need to improve access to genomic testing and life saving cancer medicines including chemotherapy and clinical trials of novel agents like PARP inhibitors. Given the high burden of inherited breast cancer, genetic risk assessment should be integrated into cancer control plans in sub-Saharan Africa.

Prediction of Burst Pressure in Multistage Tube Hydroforming of Aerospace Alloys

Bursting, an irreversible failure in tube hydroforming (THF), results mainly from the local plastic instabilities that occur when the biaxial stresses imparted during the process exceed the forming limit strains of the material. To predict the burst pressure, Oyan's and Brozzo's decoupled ductile fracture criteria (DFC) were implemented as user material models in a dynamic nonlinear commercial 3D finite-element (FE) software, ls-dyna. THF of a round to V-shape was selected as a generic representative of an aerospace component for the FE simulations and experimental trials. To validate the simulation results, THF experiments up to bursting were carried out using Inconel 718 (IN 718) tubes with a thickness of 0.9 mm to measure the internal pressures during the process. When comparing the experimental and simulation results, the burst pressure predicated based on Oyane's decoupled damage criterion was found to agree better with the measured data for IN 718 than Brozzo's fracture criterion.

Abstract P3-06-13: Transient increase in breast cancer risk after a full term pregnancy among African women

Background

African women affected by breast cancer (BC) have high parity with five children or more, are relatively young at first full term pregnancy (FFTP), are diagnosed at a young age and are often premenopausal at diagnosis. While several studies have assessed the role of reproductive factors for BC risk among African women, none of them have assessed whether there is dual effect of age at full term pregnancy (FTP). In this communications, using a large dataset from an on-going hospital-based case-control study, we examine the role of age at full term pregnancy on breast cancer risk among African women.

Methods

The study includes sites in Nigeria (University College Hospital, Ibadan), Cameroon (Yaoundé General Hospital) and Uganda (Breast Clinic of Mulago Hospital of Kampala). It was initiated in 1998 in Nigeria and extended to Cameroon and Uganda in 2011. Cases were consecutive females diagnosed with invasive BC. Controls were recruited from the community or within the hospital and have never being diagnosed with any cancer. Cases and controls were aged 18 years or more and gave informed consent. Full term pregnancy was defined as a pregnancy that lasted at least 7 months and included both live birth and stillbirth. Logistic regression models were used to assess the effects of age at first and second FTP, and their interaction with current age on BC risk. Age at menarche, parity, body mass index and hormone contraception use were included in the models.

Results

The study includes 1668 cases and 2399 controls recruited between 1998 and May 2013. Mean duration of live birth was 9 months (SD±0.52) and 8.8 months (SD±0.66) for a stillbirth. Overall, the mean age at FFTP was 23 years (SD±4.91) for both cases and controls. Compared to nulliparous women, parous women who had FFTP at 20 years have increased risk (OR = 1.59, CI 95%, 1.16-2.21) to develop BC in the year following the pregnancy. Up to 5 years following the FFTP, this OR is 1.38 (CI 95%, 1.06-1.80) while it is 0.77 (CI 95%, 0.62-0.95) 25 years later. This observation was also true for parous women who have had their FFTP at 25, 30, or 35 years. Moreover, a similar pattern was observed when comparing uniparous women to women with 2 or more children.

Conclusion

Our results show a transient increase in risk of BC after a full term pregnancy which declined and became protective over time. This observation is consistent with the effect of pregnancy on BC that has been described in other populations and may partially explain the current profile of breast cancer among African women.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-06-13.

Reference values for serum levels of folic acid and vitamin B12 in a young adult Ugandan population

INTRODUCTION

Reference values may vary significantly among populations and cultures for which dietary intakes may be different. Each laboratory is expected to investigate the transferability of the expected values to its own patient population and if necessary determine its own reference ranges. This study sought to establish Folic acid and Vitamin B(12) reference values for young Ugandan adults, which reference values could be used as baseline information for future research, especially related to their role in breast cancer prevention.

METHODS

A cross sectional study in which 200 undergraduate student volunteers were enrolled. The minimum sample size was 126 using the Open Epi version 2. Relevant demographics and physical examination parameters were taken as well as blood samples for laboratory tests. Prior ethical approval was granted.

RESULTS

The levels of folic acid were 4.17 - 20 ng/ml and remained constant over the age cohorts. The vitamin B(12) range was 117-1158 pg/ml. Both ranges were comparable to ranges seen in other populations.

CONCLUSION

In as much as the dietary intake for this study population is presumed different from populations in the western countries, the ranges for these two vitamins were similar.

Cancer of the breast: 5-year survival in a tertiary hospital in Uganda

The objective was to investigate survival of breast cancer patients at Mulago Hospital. A retrospective study of the medical records of 297 breast cancer patients referred to the combined breast clinic housed in the radiotherapy department between 1996 and 2000 was done. The female/male ratio was 24 : 1. The age range was 22-85 years, with a median of 45 years and peak age group of 30-39 years. Twenty-three percent had early disease (stages 0-IIb) and 26% had metastatic disease. Poorly differentiated was the most common pathological grade (58%) followed by moderately differentiated (33%) and well-differentiated (9%) tumours. The commonest pathological type encountered was 'not otherwise specified' (76%). Of all patients, 75% had surgery, 76% had radiotherapy, 60% had hormonotherapy and 29% had chemotherapy. Thirty-six (12%) patients received all the four treatment modalities. The 5-year survival probabilities (Kaplan-Meier) for early disease were 74 and 39% for advanced disease (P=0.001). The overall 5-year survival was 56%, which is lower than the rates in the South African blacks (64%) and North American whites (82-88%).