Hodgkin lymphoma after autoimmune diseases by age at diagnosis and histological subtype

BACKGROUND

Increased risk of Hodgkin lymphoma (HL) associated with personal history of several autoimmune diseases (ADs), such as rheumatoid arthritis, systemic lupus erythematosus, sarcoidosis, and immune thrombocytopenic purpura, are known. Whether there are other HL-related ADs and whether the increased risk of HL after ADs holds across sex, age, year of diagnosis, or HL histological subtype is unclear.

PATIENTS AND METHODS

We systematically analyzed the risk of HL in 878 161 Swedish patients diagnosed with 33 different ADs in 1964-2010. During ∼10-year follow-up of ADs patients, 371 incident HL cases were diagnosed.

RESULTS

Significantly increased overall standardized incidence ratio (SIR) for HL after ADs was 2.0 (95% confidence interval: 1.8-2.2); AD-specific SIRs: autoimmune hemolytic anemia 19.9 (7.2-43.6), sarcoidosis 10.3 (7.8-13.4), systemic lupus erythematosus 8.4 (5.2-12.9), immune thrombocytopenic purpura 7.0 (3.2-13.3), polyarteritis nodosa 6.6 (1.2-19.5), polymyositis/dermatomyositis 6.3 (2.0-14.9), Behcet's disease 5.6 (2.7-10.3), Sjögren's syndrome 5.0 (2.1-9.8), rheumatoid arthritis 3.2 (2.6-3.9), polymyalgia rheumatica 2.2 (1.4-3.5), and psoriasis 1.9 (1.3-2.6). Men with AD had slightly higher risk of HL (2.4, 2.0-2.7) compared with women (1.8, 1.5-2.0). Only 23% of ADs were diagnosed before age 35 years and the overall SIR for HL diagnosis before age 35 [1.4, (1.0-1.8)] was lower than that in older ages [35 ≤ age < 50: 2.1 (1.6-2.7); age ≥ 50: 2.2 (2.0-2.5)], except for sarcoidosis [age < 35: 19.3 (10.5-32.5); 35 ≤ age < 50: 10.4 (5.7-17.5); age ≥ 50: 8.4 (5.6-12.1)]. Risks of all classical HLs significantly increased after ADs: lymphocyte depletion 3.7 (1.5-7.6), lymphocyte-rich 3.7 (2.3-5.9), mixed cellularity 2.4 (1.8-3.2), and nodular sclerosis 1.7 (1.3-2.1).

CONCLUSION

Several, but not all ADs (11/33), had a positive association with all classical histological subtypes of HL. Higher risks of classical HL after polyarteritis nodosa, polymyositis/dermatomyositis, Behcet's disease, Sjögren's syndrome, polymyalgia rheumatica, and psoriasis were novel findings of this study.

A genome-wide association study on copy-number variation identifies a 11q11 loss as a candidate susceptibility variant for colorectal cancer

Colorectal cancer (CRC) is a complex disease, and therefore its development is determined by the combination of both environmental factors and genetic variants. Although genome-wide association studies (GWAS) of SNP variation have conveniently identified 20 genetic variants so far, a significant proportion of the observed heritability is yet to be explained. Common copy-number variants (CNVs) are one of the most important genomic sources of variability, and hence a potential source to explain part of this missing genetic fraction. Therefore, we have performed a GWAS on CNVs to explore the relationship between common structural variation and CRC development. Phase 1 of the GWAS consisted of 881 cases and 667 controls from a Spanish cohort. Copy-number status was validated by quantitative PCR for each of those common CNVs potentially associated with CRC in phase I. Subsequently, SNPs were chosen as proxies for the validated CNVs for phase II replication (1,342 Spanish cases and 1,874 Spanish controls). Four common CNVs were found to be associated with CRC and were further replicated in Phase II. Finally, we found that SNP rs1944682, tagging a 11q11 CNV, was nominally associated with CRC susceptibility (p value = 0.039; OR = 1.122). This locus has been previously related to extreme obesity phenotypes, which could suggest a relationship between body weight and CRC susceptibility.

Inherited genetic susceptibility to multiple myeloma

Although the familial clustering of multiple myeloma (MM) supports the role of inherited susceptibility, only recently has direct evidence for genetic predisposition been demonstrated. A meta-analysis of two genome-wide association (GWA) studies has identified single-nucleotide polymorphisms (SNPs) localising to a number of genomic regions that are robustly associated with MM risk. In this review, we provide an overview of the evidence supporting a genetic contribution to the predisposition to MM and MGUS (monoclonal gammopathy of unknown significance), and the insight this gives into the biological basis of disease aetiology. We also highlight the promise of future approaches to identify further specific risk factors and their potential clinical utility.

Raw grated beetroot linked to several outbreaks of sudden-onset gastrointestinal illness, Finland 2010

In 2010, 7/44 (16%) reported foodborne outbreaks in Finland were linked with raw beetroot consumption. We reviewed data from the national outbreak registry in order to hypothesize the aetiology of illness and to prevent further outbreaks. In the seven outbreaks, 124 cases among 623 respondents were identified. Consumption of raw beetroot was strongly associated with gastrointestinal illness (relative risk 8∙99, 95% confidence interval 6∙06-13∙35). The illness was characterized by sudden onset of gastrointestinal symptoms; the median incubation time was 40 min and duration of illness 5 h. No common foodborne pathogens or toxins were found in either clinical or beetroot samples, but all tested beetroot samples were of poor quality according to total bacterial counts. Beta-haemolytic Pseudomonas fluorescens was detected in several beetroot samples but its effect on human health is unknown. No outbreaks were reported after the Finnish Food Safety Authority Evira advised against serving raw beetroot in institutional canteens.

(32)P-postlabelling analysis of 1,3-butadiene-induced DNA adducts in vivo and in vitro

Butadiene monoepoxide (BMO), epoxybutanediol (EBD) and diepoxybutane (DEB) are reactive metabolites of 1,3-butadiene (BD), an important industrial chemical classified as a probable human carcinogen. The covalent interactions of these metabolites with DNA lead to the formation of DNA adducts which may induce mutations or other types of DNA damage, resulting in tumour formation. In the present study, two pairs of diastereomeric N-1-BMO-adenine adducts were identified in the reaction of BMO with 2´-deoxyadenosine-5´-monophosphate (5´-dAMP). The major products formed by reacting EBD with 2´-deoxyguanosine-5´-monophosphate (5´-dGMP) were characterized as diastereomeric N-7-(2´,3´,4´-trihydroxybut-1´-yl)-5´-dGMP by UV and electrospray mass spectrometry. The formation of N-7-BMO-guanine adducts (1´-carbon, 60; 2´carbon, 54/10(4) nucleotides) in BMO-treated DNA was about four times higher than that of N-1-BMO-adenine adducts (1´-carbon, 20; 2´-carbon, 8.7/10(4) nucleotides). However, the recovery of N-1-BMO-adenine adducts in DNA (45 ± 5%) was two times higher than that of N-7-guanine adducts (20 ± 4%) by 32P-postlabelling analysis. Using the 32P-postlabelling/ HPLC assay, N-1-BMO-adenine, N-7-BMO-guanine and N-7-EBDguanine adducts were detected in BMO- or DEB-treated DNA and in liver DNA of rats exposed to BD by inhalation. The amount of N-7-EBD-guanine adducts (11/10(8) nucleotides) in rat liver was about three-fold higher than N-7-BMO-guanine adducts (4.0/10(8) nucleotides). The novel finding of N-1-BMO-adenine adducts formed in vivo may contribute to the understanding of the mechanisms of BD carcinogenic action.

(32)P-postlabelling/HPLC analysis of various styrene-induced DNA adducts in mice

Styrene oxide (SO), a reactive metabolite of styrene, modifies DNA at several nucleophilic sites. In the present work we have determined the SO-DNA adducts in vitro and in vivo by two different versions of (32)P-postlabelling/HPLC assays. When anionexchange cartridges were used for adduct enrichment the β-isomer of 7-substituted guanines was detected in in vitro SO-treated DNA as well as in mice lungs exposed to styrene at 750 and 1500 mg m(-3) for 21 days (6 h day(-1), 7 days week(-1)). In the lungs, the adduct levels were 6.5 and 23 per 10(8) nucleotides for the two doses, respectively. When the nuclease P1 resistant adducts were studied by the (32)P-postlabelling/HPLC assay involving nuclease P1/prostatic acid phosphatase hydrolysis, the main adducts in in vitro-treated DNA were the α-isomer of N(2)-substituted guanine, β-isomers of 1-substituted adenine and 3-substituted uracil. β1-SO-adenine adduct was detected in the mice lung tissues after conversion of the 1-substituted adduct to the βN(6)-SO-adenine adduct by the Dimroth rearrangement. The 1-adenine adduct levels for the two doses were found to be 0.17 and 0.51 per 10(8) nucleotides. The current results show the potential of using the 7-guanine and 1-adenine adducts as biomarkers in biomonitoring of styrene exposure.

Time trends in survival from cancer of unknown primary: small steps forward

BACKGROUND

Cancer of unknown primary (CUP) is a fatal cancer for which incidence trends have changed but detailed survival trends remain unexplored. These could point out successful diagnostic and therapeutic approaches. We investigate survival trends in CUP according to histology, locations of metastases and site-specific causes of death.

PATIENTS AND METHODS

A total of 20,523 CUP patients with nodal and extranodal metastases were identified from the Swedish Cancer Registry. Hazard ratios (HRs) were estimated, comparing three different time periods (1987-1993, 1994-2000 and 2001-2008) with respect to histological subtype, CUP location and the cause of death.

RESULTS

Survival for patients with CUP increased over the study period (HR=0.91 [95% confidence interval (CI): 0.78-0.84], p<0.001 for trend). Adenocarcinoma was the only histology associated with increased survival (0.78 [0.74-0.82], p<0.001 for trend). Survival was improved most clearly for CUP of the pelvis (0.55 [0.36-0.83]), peritoneum (0.58 [0.53-0.65]) and nervous system (0.46 [0.29-0.72]). Survival improved substantially in patients with ovarian (0.57 [0.46-0.70]), peritoneal (0.39 [0.24-0.65]) and biliary system cancers (0.67 [0.52-0.87]). Kaplan-Meier curves showed significant survival gains for all CUP and adenocarcinoma patients (p<0.001).

CONCLUSIONS

Over time, survival for patients with CUP increased for adenocarcinoma and for CUP of the pelvis, peritoneum and nervous system. Survival trends in CUP may be related to (1) similar trends in other common metastatic tumours, particularly pancreatic and hepatobiliary cancers, which are common 'hidden' primaries for CUP, (2) earlier detection and (3) advances in the management of metastatic cancers. The improvement in survival at specific locations suggests true therapeutic gains.

Familial risk of early and late onset cancer: nationwide prospective cohort study

OBJECTIVE

To determine whether familial risk of cancer is limited to early onset cases.

DESIGN

Nationwide prospective cohort study.

SETTING

Nationwide Swedish Family-Cancer Database.

PARTICIPANTS

All Swedes born after 1931 and their biological parents, totalling >12.2 million individuals, including >1.1 million cases of first primary cancer.

MAIN OUTCOME MEASURES

Familial risks of the concordant cancers by age at diagnosis.

RESULTS

The highest familial risk was seen for offspring whose parents were diagnosed at an early age. Familial risks were significantly increased for colorectal, lung, breast, prostate, and urinary bladder cancer and melanoma, skin squamous cell carcinoma, and non-Hodgkin's lymphoma, even when parents were diagnosed at age 70-79 or 80-89. When parents were diagnosed at more advanced ages (≥ 90), the risk of concordant cancer in offspring was still significantly increased for skin squamous cell carcinoma (hazard ratio 1.9, 95% confidence interval 1.4 to 2.7), colorectal (1.6, 1.2 to 2.0), breast (1.3, 1.0 to 1.6), and prostate cancer (1.3, 1.1 to 1.6). For offspring with a cancer diagnosed at ages 60-76 whose parents were affected at age <50, familial risks were not significantly increased for nearly all cancers.

CONCLUSION

Though the highest familial risks of cancer are seen in offspring whose parents received a diagnosis of a concordant cancer at earlier ages, increased risks exist even in cancers of advanced ages. Familial cancers might not be early onset in people whose family members were affected at older ages and so familial cancers might have distinct early and late onset components.

Familial cancer in Sweden

Studies on familial clustering of cancer have usually followed transmission of a trait or mutant gene from one parental line. However, an access to families with two affected parents may additionally contribute to the models of carcinogenesis. The combined effect of parental cancer on the cancer risk of the offspring was tested in a large population-based data set. A family-cancer data base was constructed from the nationwide Swedish registries to include over 21,000 cancers in offspring diagnosed at ages 15-51 and their parents. Cancer risk in the offspring was assessed when the parents had different combinations of site-specific cancers. The risk in the offspring was increased only moderately, at most 1.1 times when the father or the mother had cancer. If both parents had cancer the risks were higher and reached statistical significance for the following paternal/maternal site-specific combinations: colorectum/colorectum, prostate/colorectum, colorectum/breast, prostate/breast, melanoma/breast and skin (squamous cell carcinoma)/breast. These results on young and middle-aged adults indicate that cancer in both parents increase cancer risk in the offspring at many sites. A likely molecular explanation is that both parents contribute with different mutant genes to the set of genes constituting the multistage pathway to carcinogenesis.

Effect of autoimmune diseases on mortality and survival in subsequent digestive tract cancers

BACKGROUND

Patients with some autoimmune diseases (AIDs) are at increased risk of cancer, possibly a result of an underlying dysregulation of the immune system, medication, treatment or, probably, surveillance bias. Data on cancer mortality and survival in patients previously diagnosed with AIDs would provide novel information on these comorbidities and their clinical implications.

PATIENTS AND METHODS

Standardized mortality ratios (SMRs) and hazard ratios (HRs) were calculated for subsequent deaths from seven digestive tract cancers between 1964 and 2008 in patients hospitalized for any of 33 AIDs.

RESULTS

There were 33 increased SMRs for specific cancers after a defined AID; similarly, 21 HRs were increased. Both the SMR and HR were increased after 10 autoimmune disorders, including pernicious anemia, systemic lupus erythematosus and psoriasis. Increased SMRs and unchanged HRs were noted for 23 cancers. Myasthenia gravis was associated with SMRs for five cancers but no increases in HRs. For nine cancers, including esophageal cancer after ulcerative colitis and rheumatoid arthritis, the SMR was unchanged but the HR increased.

CONCLUSIONS

The increases in SMRs provide evidence that cancer risks were truly increased and largely unaffected by surveillance bias. The prognostic survival data should contribute to clinical evaluation and therapeutic planning.

Site-specific cancer deaths in cancer of unknown primary diagnosed with lymph node metastasis may reveal hidden primaries

Cancer of unknown primary site (CUP) is a fatal cancer ranking among the five most common cancer deaths. CUP is diagnosed through metastases, which are limited to lymph nodes in some patients. Cause-specific survival data could guide the search for hidden primary tumors and help with therapeutic choices. The CUP patients were identified from the Swedish Cancer Registry between 1987 and 2008; 1,444 patients had only lymph node metastasis of defined histology (adenocarcinoma, squamous cell or undifferentiated). Site-specific cancer deaths were analyzed by lymph node location and histology. Kaplan-Meier survival curves were compared with metastatic primary cancer at related sites. Among the patients with metastasis to head and neck lymph nodes, 117 (59.1% of the specific cancer deaths) died of lung tumors. Patients with axillary lymph node metastasis died of lung and breast tumors in equal proportions (40.2% each). Also, squamous cell CUP in head and neck lymph nodes was mainly associated with lung tumor deaths (53.1%). With a few exceptions, survival of CUP patients with lymph node metastasis was indistinguishable from survival of patients with metastatic primary cancer originating from the organs drained by those nodes. The association between lymph node CUP metastases with cancer deaths in the drained organ and the superimposable survival kinetics suggests that drained organs host hidden primaries. Importantly, half of all site-specific cancer deaths (266/530) were due to lung tumors. Thus, an intense search should be mounted to find lung cancer in CUP patients with lymph node metastases.

Mutations and polymorphisms in TP53 gene--an overview on the role in colorectal cancer

A functionally normal TP53 is essential to protect organisms from developing cancer. Somatic mutations in the gene represent one of the highest recurring perturbations in human tumours, including colorectal cancer (CRC). However, the variegated phenotype of wide spectrum of somatic mutations in TP53 and the complexity of the disease prevent a straight interpretation of the mutational analysis in tumours. In addition to the presence of somatic mutations, polymorphic features of the gene may also contribute to alteration of the normal TP53 functioning and variants, mainly in the form of single nucleotide polymorphisms, can be expected to impact susceptibility to sporadic CRC. In the present study, we reviewed the potential role of alterations in the TP53 gene, both somatic mutations and inherited sequence variations, in predisposition to CRC and in the prognosis and response to therapy. The available data from association studies have mostly shown contradictory outcomes. The majority of the studies were based on limited sample sizes and focussed on a limited number of polymorphisms, with main being the rs1042522 (Arg72Pro). Thus far, there is no possible generalisation of the role of TP53 as also a predictor of therapeutic response and prognosis. The effects of TP53, and its abnormalities, on the response of tumours to cytotoxic drugs, radiation and chemoradiation are complex. However, from studies it is emerging that the inherited genetics of TP53 pathway components could be utilised to further define patient populations in their abilities to induce p53 activity in response to either DNA damaging or p53-targeted therapies.

Cancer of unknown primary (CUP): does cause of death and family history implicate hidden phenotypically changed primaries?

BACKGROUND

Cancer of unknown primary (CUP) is diagnosed at the metastatic stage. We aimed to identify hidden primary cancers in CUP patients by comparison with cancers in family members. We take use of the fact that the cause of death in CUP patients is often coded as the cancer in the organ of fatal metastasis.

PATIENTS AND METHODS

Forty-one thousand five hundred and twenty-three CUP patients were identified in the Swedish Family-Cancer Database, and relative risks (RRs) were calculated for cancer in offspring when family members were diagnosed with CUP and died of the cancer diagnosed in offspring.

RESULTS

The RR for lung cancer in offspring was 1.85 when a family member was diagnosed with CUP and died of lung cancer. Significant familial associations were found for seven other cancers. Many familial associations were also significant when offspring CUP patients died of the cancer diagnosed in family members.

CONCLUSIONS

The cause of death after CUP diagnosis frequently matched the cancer found in a family member, suggesting that the CUP had originated in that tissue. The metastasis had probably undergone a phenotypic change, complicating pathological tissue assignment. These novel data suggest that some CUP cases are phenotypically modified primary cancers rather than cancers of unknown primaries.

Power and limits of modern cancer diagnostics: cancer of unknown primary

BACKGROUND

Cancer of unknown primary (CUP) is diagnosed at a metastatic stage but no diagnostic effort is spared to find the primary cancers because these will guide the treatment. Consequently, the diagnostic work-up for CUP is more comprehensive than for any other cancer, resulting in detection of second cancers unrelated to CUP. We want to use the detection rate of second cancers as a measure of efficacy of the diagnostic modalities in finding tumors, assuming that the detection rates have increased with modern technologies.

PATIENTS AND METHODS

The number of CUP patients identified in the nation-wide Swedish Database was 28,574 and relative risks (RRs) for second cancers were recorded in three periods from 1980 through 2008. The first 5 months after CUP were considered critical for second cancers to be diagnosed during the intense work-up for CUP.

RESULTS

Among second cancers, diagnosable by computed tomography or magnetic resonance imaging, there was a large 6.80-fold increase in RR immediately following CUP diagnosis from the period 1980-1989 to 2000-2008. Over the same periods, the increase in in situ tumors was 7.16-fold.

CONCLUSION

These data suggest that improvements in the resolution and availability of powerful imaging techniques result in increasingly sensitive detection of tumors.

Death causes in breast cancer patients

BACKGROUND

Due to improved outcomes in breast cancer (BCa), the proportion of affected women dying of other causes has increased. Thus, a better survival of BCa requires knowledge of other causes of death.

MATERIALS AND METHODS

Data on the population, cancers, and causes of death were gathered from the nationwide Swedish Family-Cancer Database, enrolling ∼3.68 million Swedish women. A Cox regression model, comparing BCa patients against all other women, was applied. Cause-of-death-specific hazard ratios (HRs) were calculated for both underlying and multiple causes of death.

RESULTS

Among 641 000 deaths from 1987 to 2006, 48,000 were BCa patients. For underlying causes except BCa, the highest cause-specific HRs were found for diseases of pulmonary circulation {1.51 [95% confidence interval (CI) 1.36-1.68]}, suicide [1.39 (1.19-1.63)], and heart failure [1.29 (1.22-1.37)]. For specific multiple causes, the highest ratios were found for external causes [1.86 (1.80-1.91)] and gastrointestinal disease [1.68 (1.62-1.74)].

CONCLUSIONS

Diagnosis of BCa is associated with increased risks of dying of various causes, including external causes, heart failure, diseases of pulmonary circulation, and gastrointestinal disease. The study fulfills the gap in knowledge of death causes in BCa patients and suggests to draw more attention to comorbidities.

Subsequent cancers in patients diagnosed with cancer of unknown primary (CUP): etiological insights?

BACKGROUND

Patterns of subsequent malignancies in patients with cancer of unknown primary (CUP) may provide etiological insight into the primary tumor. The objective of the present study is to quantify risks of the subsequent cancers in CUP patients since such studies are lacking.

PATIENTS AND METHODS

A population-based cohort of CUP was identified from the Swedish Family-Cancer Database of year 2008. Standardized incidence ratios (SIRs) were calculated for developing the following malignancies in 31,357 CUP patients from 1975 to 2008.

RESULTS

A total of 755 CUP patients developed subsequent cancers, showing a significantly increased overall SIR of 1.69 (95% confidence interval 1.57-1.81). Among the most common 32 malignancies, increased SIRs were noted for 16 sites. Over 10-fold increases were observed for squamous cell carcinoma at four sites, possibly as a result of uncontrolled human papillomavirus infection due to faltering immune surveillance. The highest SIRs were observed among CUP patients diagnosed at a younger age and during the first follow-up year.

CONCLUSIONS

Swedish CUP survivors had a higher risk of developing many subsequent cancers. Different patterns of risk excess may be suggestive of possible roles for disease- and therapy-related immunosuppression, reappearance of hidden primary tumors, or genetic predisposition.

Risk for incident and fatal prostate cancer in men with a family history of any incident and fatal cancer

BACKGROUND

Familial clustering of incident prostate cancer and some cancers at other discordant sites has been reported. Less is known about familial clustering of fatal prostate cancer with any fatal discordant cancers. Estimates on familial aggregation based on mortality are free from bias of overdiagnosis.

PATIENTS AND METHODS

We used the nationwide Swedish Family-Cancer Database to calculate standardized incidence ratios (SIRs) for incident prostate cancer for relatives of patients with any common cancer and standardized mortality ratios (SMRs) for death in prostate cancer for relatives of individuals who died from cancer. Similar risks were determined for any common cancer when relatives were affected by prostate cancer.

RESULTS

We observed familial aggregation of incident and fatal prostate cancers. Familial clustering (SIRs increased) of prostate cancer and of cancers at discordant sites was found for breast, ovarian, and kidney cancers and melanoma. Also, fatal prostate cancer clustered with these and cervical cancers (SMRs increased).

CONCLUSIONS

Our findings demonstrate that familial aggregation of prostate and breast cancers are not due to shared screening habits. The data on the association of cancers at discordant sites might be useful for clinical counseling and for mechanistic studies searching explanations to the familial clustering between discordant cancers.

Survival in cancer of unknown primary site: population-based analysis by site and histology

BACKGROUND

Cancer of unknown primary (CUP) is diagnosed at a metastatic stage, conferring an unfavorable prognosis. The natural history of the disease is poorly understood, which complicates diagnosis, treatment and follow-up. Population-based survival data are lacking regarding location and histology of metastases.

PATIENTS AND METHODS

From the Swedish Cancer Registry, 18 911 CUP patients were identified between years 1987 and 2008. Survival was analyzed by Kaplan-Meier survival curves and Cox regression.

RESULTS

Adenocarcinoma accounted for 70% of all extranodal cases with a 12-month survival of 17% and the median survival of 3 months. Adenocarcinoma was also the most common histology (33.4%) when metastases were limited to lymph nodes, with a 12-month survival of 41% and median survival of 8 months. For extranodal metastases, the extremes in survival were small intestinal cancer with poor prognosis and mediastinal cancer with favorable prognosis. For nodal metastases, patients affected in the head and neck, axillary and inguinal regions had the best prognosis and those with abdominal and intrapelvic metastases the worst prognosis.

CONCLUSIONS

The present data underline the importance of histology and location of metastasis in assisting clinical decision making: hazard ratios differed by a factor of five among extranodal and nodal metastases.

Combined effect of low-penetrant SNPs on breast cancer risk

BACKGROUND

Although many low-penetrant genetic risk factors for breast cancer have been discovered, knowledge about the effect of multiple risk alleles is limited, especially in women <50 years. We therefore investigated the association between multiple risk alleles and breast cancer risk as well as individual effects according to age-approximated pre- and post-menopausal status.

METHODS

Ten previously described breast cancer-associated single-nucleotide polymorphisms (SNPs) were analysed in a joint European biobank-based study comprising 3584 breast cancer cases and 5063 cancer-free controls. Genotyping was performed using MALDI-TOF mass spectrometry, and odds ratios were estimated using logistic regression.

RESULTS

Significant associations with breast cancer were confirmed for 7 of the 10 SNPs. Analysis of the joint effect of the original 10 as well as the statistically significant 7 SNPs (rs2981582, rs3803662, rs889312, rs13387042, rs13281615, rs3817198 and rs981782) found a highly significant trend for increasing breast cancer risk with increasing number of risk alleles (P-trend 5.6 × 10(-20) and 1.5 × 10(-25), respectively). Odds ratio for breast cancer of 1.84 (95% confidence interval (CI): 1.59-2.14; 10 SNPs) and 2.12 (95% CI: 1.80-2.50; 7 SNPs) was seen for the maximum vs the minimum number of risk alleles. Additionally, one of the examined SNPs (rs981782 in HCN1) had a protective effect that was significantly stronger in premenopausal women (P-value: 7.9 × 10(-4)).

CONCLUSION

The strongly increasing risk seen when combining many low-penetrant risk alleles supports the polygenic inheritance model of breast cancer.