Variants in ATRIP are associated with breast cancer susceptibility in the Polish population and UK Biobank.

Several breast cancer susceptibility genes have been discovered, but more are likely to exist. To identify additional breast cancer susceptibility genes, we used the founder population of Poland and performed whole-exome sequencing on 510 women with familial breast cancer and 308 control subjects. We identified a rare mutation in ATRIP (GenBank: NM_130384.3: c.1152_1155del [p.Gly385Ter]) in two women with breast cancer. At the validation phase, we found this variant in 42/16,085 unselected Polish breast cancer-affected individuals and in 11/9,285 control subjects (OR = 2.14, 95% CI = 1.13-4.28, p = 0.02). By analyzing the sequence data of the UK Biobank study participants (450,000 individuals), we identified ATRIP loss-of-function variants among 13/15,643 breast cancer-affected individuals versus 40/157,943 control subjects (OR = 3.28, 95% CI = 1.76-6.14, p < 0.001). Immunohistochemistry and functional studies showed the ATRIP c.1152_1155del variant allele is weakly expressed compared to the wild-type allele, and truncated ATRIP fails to perform its normal function to prevent replicative stress. We showed that tumors of women with breast cancer who have a germline ATRIP mutation have loss of heterozygosity at the site of ATRIP mutation and genomic homologous recombination deficiency. ATRIP is a critical partner of ATR that binds to RPA coating single-stranded DNA at sites of stalled DNA replication forks. Proper activation of ATR-ATRIP elicits a DNA damage checkpoint crucial in regulating cellular responses to DNA replication stress. Based on our observations, we conclude ATRIP is a breast cancer susceptibility gene candidate linking DNA replication stress to breast cancer.

The impact of oophorectomy on survival from breast cancer in patients with CHEK2 mutations.

BACKGROUND: To estimate the impact of oophorectomy and other treatments on the survival of breast cancer patients with a CHEK2 mutation. METHODS: Women with Stage I-III breast cancer who were treated at 17 hospitals in Poland were tested for four founder mutations in the CHEK2 gene. 974 women (10%) were positive for a CHEK2 mutation. Control patients without a CHEK2 mutation were selected from a database of patients treated over the same time period. Information on treatments received and distant recurrences were retrieved from medical records. Treatments included chemotherapy, hormonal therapy (tamoxifen) and radiation therapy. Oophorectomies were performed for the treatment of breast cancer or for benign conditions. Dates of death were obtained from the Polish Vital Statistics Registry. Causes of death were determined by medical record review. Predictors of survival were determined using the Cox proportional hazards model. RESULTS: In all, 839 patients with a CHEK2 mutation were matched to 839 patients without a mutation. The mean follow-up was 12.0 years. The 15-year survival for CHEK2 carriers was 76.6% and the 15-year survival for non-carrier control patients was 78.8% (adjusted HR = 1.06; 95% CI: 0.84-1.34; P = 0.61). Among CHEK2 carriers, the 15-year survival for women who had an oophorectomy was 86.3% and for women who did not have an oophorectomy was 72.1% (adjusted HR = 0.59; 95% CI: 0.38-0.90; P = 0.02). Among controls, the 15-year survival for patients who had an oophorectomy was 84.5% and for women who did not have an oophorectomy was 77.6% (adjusted HR = 1.03; 95% CI: 0.66-1.61; P = 0.90). CONCLUSION: Among women with breast cancer and a CHEK2 mutation, oophorectomy is associated with a reduced risk of death from breast cancer.

PALB2 mutations and prostate cancer risk and survival.

BACKGROUND: The objective of this study was to establish the contribution of PALB2 mutations to prostate cancer risk and to estimate survival among PALB2 carriers. METHODS: We genotyped 5472 unselected men with prostate cancer and 8016 controls for two Polish founder variants of PALB2 (c.509_510delGA and c.172_175delTTGT). In patients with prostate cancer, the survival of carriers of a PALB2 mutation was compared to that of non-carriers. RESULTS: A PALB2 mutation was found in 0.29% of cases and 0.21% of controls (odds ratio (OR) = 1.38; 95% confidence interval (CI) 0.70-2.73; p = 0.45). PALB2 mutation carriers were more commonly diagnosed with aggressive cancers of high (8-10) Gleason score than non-carriers (64.3 vs 18.1%, p < 0.0001). The OR for high-grade prostate cancer was 8.05 (95% CI 3.57-18.15, p < 0.0001). After a median follow-up of 102 months, the age-adjusted hazard ratio for all-cause mortality associated with a PALB2 mutation was 2.52 (95% CI 1.40-4.54; p = 0.0023). The actuarial 5-year survival was 42% for PALB2 carriers and was 72% for non-carriers (p = 0.006). CONCLUSION: In Poland, PALB2 mutations predispose to an aggressive and lethal form of prostate cancer.

Genetic predisposition to male breast cancer in Poland.

BACKGROUND: Breast cancer in men accounts for fewer than 1 % of all breast cancer cases diagnosed in men and women. Genes which predispose to male breast cancer include BRCA1 and BRCA2. The role of other genes is less clear. In Poland, 20 founder mutations in BRCA1, BRCA2, CHEK2, PALB2, NBN, RECQL are responsible for the majority of hereditary breast cancer cases in women, but the utility this genes panel has not been tested in men. METHODS: We estimated the prevalence of 20 alleles in six genes (BRCA1, BRCA2, CHEK2, PALB2, NBN, RECQL) in 165 Polish male breast cancer patients. We compared the frequency of selected variants in male breast cancer cases and controls. RESULTS: One of the 20 mutations was seen in 22 of 165 cases (13.3%). Only one BRCA1 mutation and two BRCA2 mutations were found. We observed statistically significant associations for PALB2 and CHEK2 truncating mutations. A PALB2 mutation was detected in four cases (OR = 11.66; p < 0.001). A CHEK2 truncating mutation was detected in five cases (OR = 2.93;p = 0.02). CONCLUSION: In conclusion, we recommend that a molecular test for BRCA1, BRCA2, PALB2 and CHEK2 recurrent mutations should be offered to male breast cancer patients in Poland.

Recurrent PALB2 mutations and the risk of cancers of bladder or kidney in Polish population.

INTRODUCTION: The role of PALB2 in carcinogenesis remains to be clarified. Our main goal was to determine the prevalence of PALB2 (509_510delGA and 172_175delTTGT) mutations in bladder and kidney cancer patients from Polish population. MATERIALS AND METHODS: 1413 patients with bladder and 810 cases with kidney cancer and 4702 controls were genotyped for two PALB2 variants: 509_510delGA and 172_175delTTGT. RESULTS: Two mutations of PALB2 gene were detected in 5 of 1413 (0.35%) unselected bladder cases and in 10 of 4702 controls (odds ratio [OR], 1.7; 95% CI 0.56-4.88; p = 0.52). Among 810 unselected kidney cancer cases two PALB2 mutations were reported in two patients (0,24%) (odds ratio [OR], (OR = 1.2; 95% CI 0.25-5.13; p = 0.84). In cases with mutations in PALB2 gene cancer family history was negative. CONCLUSION: We found no difference in the prevalence of recurrent PALB2 mutations between cases and healthy controls. The mutations in PALB2 gene seem not to play a major role in bladder and kidney cancer development in Polish patients.

Mutations in ATM, NBN and BRCA2 predispose to aggressive prostate cancer in Poland.

In designing national strategies for genetic testing, it is important to define the full spectrum of pathogenic mutations in prostate cancer (PCa) susceptibility genes. To investigate the frequency of mutations in PCa susceptibility genes in Polish familial PCa cases and to estimate gene-related PCa risks and probability of aggressive disease, we analyzed the coding regions of 14 genes by exome sequencing in 390 men with familial prostate cancer and 308 cancer-free controls. We compared the mutation frequencies between PCa cases and controls. We also compared clinical characteristics of prostate cancers between mutation carriers and noncarriers. Of the 390 PCa cases, 76 men (19.5%) carried a mutation in BRCA1, BRCA2, NBN, ATM, CHEK2, HOXB13, MSH2 or MSH6 genes. No mutations were found in BRIP1, PTEN, TP53, MLH1, PMS2 and SPOP. Significant associations with familial PCa risk were observed for CHEK2, NBN, ATM, and HOXB13. High-grade (Gleason 8-10) tumors were seen in 56% of BRCA2, NBN or ATM carriers, compared to 21% of patients who tested negative for mutations in these genes (OR = 4.7, 95% CI 2.0-10.7, P = .0003). In summary, approximately 20% of familial prostate cancer cases in Poland can be attributed to mutations in eight susceptibility genes. Carriers of mutations in BRCA2, NBN and ATM develop aggressive disease and may benefit from intensified screening and/or chemotherapy.

The spectrum of mutations predisposing to familial breast cancer in Poland.

To optimize genetic testing, it is necessary to establish the spectrum of breast cancer-predisposing mutations in particular ethnic groups. We studied 1,018 women with a strong family history for breast cancer (families with hereditary breast cancer; HBC) from genetically homogenous population of Poland, which is populated by ethnic Slavs, for mutations in 14 cancer susceptibility genes. Additionally, we compared the frequency of candidate pathogenic variants in breast cancer cases and controls. Germline mutations were detected in 512 of 1,018 probands with breast cancer (50.3%), including BRCA1/2 mutations detected in 420 families and non-BRCA mutations seen in 92 families. Thirteen BRCA1/2 founder mutations represented 84% of all BRCA1/2-positive cases. Seven founder mutations of CHEK2, PALB2, NBN and RECQL represented 73% of all non-BRCA-positive cases. Odds ratios for hereditary breast cancer were 87.6 for BRCA1, 15.4 for PALB2, 7.2 for CHEK2, 2.8 for NBN and 15.8 for RECQL. Odds ratios for XRCC2, BLM and BARD1 were below 1.3. In summary, we found that 20 founder mutations in six genes (BRCA1/2, CHEK2, PALB2, NBN and RECQL) are responsible for 82% of Polish hereditary breast cancer families. A simple test for these 20 mutations will facilitate genetic testing for breast cancer susceptibility in Poland. It may also facilitate genetic testing for breast cancer susceptibility in other Slavic populations and women of Slavic descent worldwide.

Inherited variants in XRCC2 and the risk of breast cancer.

BACKGROUND: XRCC2 participates in homologous recombination and in DNA repair. XRCC2 has been reported to be a breast cancer susceptibility gene and is now included in several breast cancer susceptibility gene panels. METHODS: We sequenced XRCC2 in 617 Polish women with familial breast cancer and found a founder mutation. We then genotyped 12,617 women with breast cancer and 4599 controls for the XRCC2 founder mutation. RESULTS: We identified a recurrent truncating mutation of XRCC2 (c.96delT, p.Phe32fs) in 3 of 617 patients with familial breast cancer who were sequenced. The c.96delT mutation was then detected in 29 of 12,617 unselected breast cancer cases (0.23%) compared to 11 of 4599 cancer-free women (0.24%) (OR = 0.96; 95% CI 0.48-1.93). The mutation frequency in 1988 women with familial breast cancer was 0.2% (OR = 0.84, 95% CI 0.27-2.65). Breast cancers in XRCC2 mutation carriers and non-carriers were similar with respect to age of diagnosis and clinical characteristics. Loss of the wild-type XRCC2 allele was observed only in one of the eight breast cancers from patients who carried the XRCC2 mutation. No cancer type was more common in first- or second-degree relatives of XRCC2 mutation carriers than in relatives of the non-carriers. CONCLUSION: XRCC2 c.96delT is a protein-truncating founder variant in Poland. There is no evidence that this mutation predisposes to breast cancer (and other cancers). It is premature to consider XRCC2 as a breast cancer-predisposing gene.

Allelic modification of breast cancer risk in women with an NBN mutation.

BACKGROUND: NBN 657del5 founder mutation predisposes to breast and prostate cancer. Recently, it has been reported that the pathogenicity of this mutation with regard to prostate cancer risk is modified by a missense variant of the same gene (E185Q). METHODS: To evaluate the interaction of the 657del5 and E185Q founder alleles of NBN on breast cancer risk in Poland, 4964 women with breast cancer and 6152 controls were genotyped for these two recurrent variants of NBN (657del5 truncating variant and E185Q missense variant). RESULTS: The NBN 657del5 mutation was detected in 57 of 4964 unselected cases and in 35 of 6152 controls (OR = 2.0, p = 0.001). The E185Q GG genotype was detected in 2167 of 4964 unselected cases and in 2617 of 6152 controls (OR = 1.04, p = 0.3). In carriers of the 657del5 deletion, the elevated cancer risk was restricted to women with the GG genotype of the E185Q variant (OR = 3.6, 95% CI 1.9-6.6; p < 0.0001). Among women with other E185Q genotypes, the OR associated with 657del5 was 1.0 (95% CI 0.5-1.8; p = 0.9). The interaction between the two alleles was statistically significant (homogeneity p = 0.003). CONCLUSION: In Poland, the pathogenicity of the NBN 657del5 mutation is restricted to women with a homozygous GG genotype of missense variant of the same gene (E185Q). This is the first clear example whereby a moderate penetrance breast cancer gene is impacted by a genetic modifier.

Prostate-specific antigen velocity in a prospective prostate cancer screening study of men with genetic predisposition.

BACKGROUND: Prostate-specific antigen (PSA) and PSA-velocity (PSAV) have been used to identify men at risk of prostate cancer (PrCa). The IMPACT study is evaluating PSA screening in men with a known genetic predisposition to PrCa due to BRCA1/2 mutations. This analysis evaluates the utility of PSA and PSAV for identifying PrCa and high-grade disease in this cohort. METHODS: PSAV was calculated using logistic regression to determine if PSA or PSAV predicted the result of prostate biopsy (PB) in men with elevated PSA values. Cox regression was used to determine whether PSA or PSAV predicted PSA elevation in men with low PSAs. Interaction terms were included in the models to determine whether BRCA status influenced the predictiveness of PSA or PSAV. RESULTS: 1634 participants had ⩾3 PSA readings of whom 174 underwent PB and 45 PrCas diagnosed. In men with PSA >3.0 ng ml-l, PSAV was not significantly associated with presence of cancer or high-grade disease. PSAV did not add to PSA for predicting time to an elevated PSA. When comparing BRCA1/2 carriers to non-carriers, we found a significant interaction between BRCA status and last PSA before biopsy (P=0.031) and BRCA2 status and PSAV (P=0.024). However, PSAV was not predictive of biopsy outcome in BRCA2 carriers. CONCLUSIONS: PSA is more strongly predictive of PrCa in BRCA carriers than non-carriers. We did not find evidence that PSAV aids decision-making for BRCA carriers over absolute PSA value alone.

Prostate-specific antigen velocity in a prospective prostate cancer screening study of men with genetic predisposition.

This corrects the article DOI: 10.1038/bjc.2017.429.

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans.

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same region.

Clinical outcomes in women with breast cancer and a PALB2 mutation: a prospective cohort analysis.

BACKGROUND: Mutations in PALB2 predispose to breast cancer, but the effect on prognosis of carrying a PALB2 mutation has not been ascertained. We aimed to estimate the odds ratio for breast cancer in women with an inherited mutation in PALB2 and 10-year survival after breast cancer in patients who carry a PALB2 mutation. METHODS: Between 1996 and 2012, patients with invasive breast cancer were recruited prospectively from 18 hospitals in Poland and genotyped for two deleterious mutations in PALB2 (509_510delGA and 172_175delTTGT). A control group of 4702 women without cancer was recruited for comparison. The primary endpoint was death from any cause, as determined by medical records from the Polish Ministry of the Interior and Administration. In patients with breast cancer, 10-year survival of carriers of a PALB2 mutation was calculated and compared with that of non-carriers. FINDINGS: 17 900 women with breast cancer were invited to participate, of whom 12 529 were genotyped successfully. A PALB2 mutation was present in 116 (0·93%, 95% CI 0·76-1·09) of 12 529 patients and in ten (0·21%, 0·08-0·34) of 4702 controls (odds ratio 4·39, 95% CI 2·30-8·37; p<0·0001). 10-year survival for women with breast cancer and a PALB2 mutation was 48·0% (95% CI 36·5-63·2), compared with 74·7% (73·5-75·8) for patients with breast cancer without a mutation (adjusted hazard ratio for death 2·27, 95% CI 1·64-3·15; p<0·0001). INTERPRETATION: Women with a PALB2 mutation face an increased risk of breast cancer and might be at a higher risk of death from breast cancer compared with non-carriers. Increased surveillance should be offered to unaffected women who carry a PALB2 mutation. FUNDING: Polish National Science Centre.

CHEK2 mutations and the risk of papillary thyroid cancer.

Mutations in the cell cycle checkpoint kinase 2 (CHEK2) tumor suppressor gene are associated with multi-organ cancer susceptibility including cancers of the breast and prostate. A genetic association between thyroid and breast cancer has been suggested, however little is known about the determinants of this association. To characterize the association of CHEK2 mutations with thyroid cancer, we genotyped 468 unselected patients with papillary thyroid cancer and 468 (matched) cancer-free controls for four founder mutations of CHEK2 (1100delC, IVS2 + 1G>A, del5395 and I157T). We compared the family histories reported by patients with a CHEK2 mutation to those of non-carriers. A CHEK2 mutation was seen in 73 of 468 (15.6%) unselected patients with papillary thyroid cancer, compared to 28 of 460 (6.0%) age- and sex-matched controls (OR 3.3; p < 0.0001). A truncating mutation (IVS2 + 1G>A, 1100delC or del5395) was associated with a higher risk of thyroid cancer (OR = 5.7; p = 0.006), than was the missense mutation I157T (OR = 2.8; p = 0.0001). CHEK2 mutation carriers reported a family history of breast cancer 2.2 times more commonly than non-carriers (16.4% vs.8.1%; p = 0.05). A CHEK2 mutation was found in seven of 11 women (63%) with multiple primary cancers of the breast and thyroid (OR = 10; p = 0.0004). These results suggest that CHEK2 mutations predispose to thyroid cancer, familial aggregations of breast and thyroid cancer and to double primary cancers of the breast and thyroid.

The presence of prostate cancer at biopsy is predicted by a number of genetic variants.

Several single nucleotide polymorphisms (SNPs) have been associated with an elevated risk of prostate cancer risk. It is not established if they are useful in predicting the presence of prostate cancer at biopsy or if they can be used to define a low-risk group of men. In this study, 4,548 men underwent a prostate biopsy because of an elevated prostate specific antigen (PSA; ≥4 ng/mL) or an abnormal digital rectal examination (DRE). All men were genotyped for 11 selected SNPs. The effect of each SNP, alone and in combination, on prostate cancer prevalence was studied. Of 4,548 men: 1,834 (40.3%) were found to have cancer. A positive association with prostate cancer was seen for 5 of 11 SNPs studied (rs1800629, rs1859962, rs1447295, rs4430796, rs11228565). The cancer detection rate rose with the number of SNP risk alleles from 29% for men with no variant to 63% for men who carried seven or more risk alleles (OR = 4.2; p = 0.002). The SNP data did not improve the predictive power of clinical factors (age, PSA and DRE) for detecting prostate cancer (AUC: 0.726 vs. 0.735; p = 0.4). We were unable to define a group of men with a sufficiently low prevalence of prostate cancer that a biopsy might have been avoided. In conclusion, our data do not support the routine use of SNP polymorphisms as an adjunct test to be used on the context of prostate biopsy for Polish men with an abnormal screening test.

The G84E mutation in the HOXB13 gene is associated with an increased risk of prostate cancer in Poland.

BACKGROUND: The G84E mutation in the HOXB13 gene has been associated with a high lifetime risk of prostate cancer in North America (about 20-fold). The geographical and ethnic extent of this recurrent allele has not yet been determined. METHODS: We assayed for the presence of the G84E mutation in 3,515 prostate cancer patients and 2,604 controls from Poland and estimated the odds ratio for prostate cancer associated with the allele. RESULTS: The G84E mutation was detected in 3 of 2,604 (0.1%) individuals from the general population in Poland and in 20 of 3,515 (0.6%) men with prostate cancer (Odds ratio [OR] = 5.0; 95% CI: 1.5-16.7; P = 0.008). The allele was present in 4 of 416 (1.0%) men with familial prostate cancer (OR = 8.4, 95% CI: 1.9-37.7; P = 0.005). CONCLUSIONS: The G84E mutation predisposes to prostate cancer in Poland, but accounts for only a small proportion of cases. We expect that the G84E founder mutation might be present in other Slavic populations.

The APOBEC3B c.783delG Truncating Mutation Is Not Associated with an Increased Risk of Breast Cancer in the Polish Population.

The APOBEC3B gene belongs to a cluster of DNA-editing enzymes on chromosome 22 and encodes an activation-induced cytidine deaminase. A large deletion of APOBEC3B was associated with increased breast cancer risk, but the evidence is inconclusive. To investigate whether or not APOBEC3B is a breast cancer susceptibility gene, we sequenced this gene in 617 Polish patients with hereditary breast cancer. We detected a single recurrent truncating mutation (c.783delG, p.Val262Phefs) in four of the 617 (0.65%) hereditary cases by sequencing. We then genotyped an additional 12,484 women with unselected breast cancer and 3740 cancer-free women for the c.783delG mutation. The APOBEC3B c.783delG allele was detected in 60 (0.48%) unselected cases and 19 (0.51%) controls (OR = 0.95, 95% CI 0.56-1.59, p = 0.94). The allele was present in 8 of 1968 (0.41%) familial breast cancer patients from unselected cases (OR = 0.80, 95% CI 0.35-1.83, p = 0.74). Clinical characteristics of breast tumors in carriers of the APOBEC3B mutation and non-carriers were similar. No cancer type was more frequent in the relatives of mutation carriers than in those of non-carriers. We conclude the APOBEC3B deleterious mutation p.Val262Phefs does not confer breast cancer risk. These data do not support the hypothesis that APOBEC3B is a breast cancer susceptibility gene.

Characterizing prostate cancer risk through multi-ancestry genome-wide discovery of 187 novel risk variants.

The transferability and clinical value of genetic risk scores (GRSs) across populations remain limited due to an imbalance in genetic studies across ancestrally diverse populations. Here we conducted a multi-ancestry genome-wide association study of 156,319 prostate cancer cases and 788,443 controls of European, African, Asian and Hispanic men, reflecting a 57% increase in the number of non-European cases over previous prostate cancer genome-wide association studies. We identified 187 novel risk variants for prostate cancer, increasing the total number of risk variants to 451. An externally replicated multi-ancestry GRS was associated with risk that ranged from 1.8 (per standard deviation) in African ancestry men to 2.2 in European ancestry men. The GRS was associated with a greater risk of aggressive versus non-aggressive disease in men of African ancestry (P = 0.03). Our study presents novel prostate cancer susceptibility loci and a GRS with effective risk stratification across ancestry groups.

Different CHEK2 germline mutations are associated with distinct immunophenotypic molecular subtypes of breast cancer.

Germline mutations in BRCA1 were already linked to basal-like subtype of immunophenotypic molecular classification of breast cancer (BC). However, it is not known whether mutations in other BC susceptibility genes are associated with molecular subtypes of this cancer. We tested the hypothesis that distinct mutations in another BC susceptibility gene involved in DNA repair, i.e., CHEK2 may be associated with particular immunophenotypic molecular subtypes of this cancer. Two groups of patients: 1255 with BCs and 5496 healthy controls were genotyped for four CHEK2 mutations (I157T and three truncating mutations: 1100delC, IVS2 + 1G > A, del5395). BCs were tested by immunohistochemistry on tissue microarrays for ER, PR, HER-2, EGFR, and CK5/6 and were assigned to appropriate subtypes of immunophenotypic molecular classification. There was a significant association between CHEK2 mutations and the immunophenotypic molecular classification (P = 0.004). CHEK2-associated cancers were predominantly luminal (108/117 = 92.3%). CHEK2-I157T variant was associated with the luminal A subtype (P = 0.01), whereas CHEK2-truncating mutations were associated with the luminal B subtype (P = 0.005). Comparing the prevalence of CHEK2 mutations in BC with controls revealed that carriers of an I157T variant had OR of 1.80 for luminal A subtype and carriers of truncating mutations had OR of 6.26 for luminal B subtype of BC. To our knowledge, this is the first study showing that specific mutations in the same susceptibility gene are associated with different immunophenotypic molecular subtypes of BC. This association represents independent evidence supporting the biological significance of immunophenotypic molecular classification of BC.

The HOXB13 p.Gly84Glu mutation is not associated with the risk of breast cancer.

Recently, the HOXB13 gene has been shown to be a susceptibility gene for prostate cancer. HOXB13 is overexpressed in breast cancer tissues and HOXB13 expression in combination with low expression of IL17BR is predictive for a tamoxifen response in ER-positive breast cancers. Based on observations, we hypothesized that the HOXB13 p.Gly84Glu mutation might be associated with breast cancer risk. We genotyped this mutation in the germline DNA of 4,037 women with breast cancer (including 1,082 familial cases) and in 2,762 controls from Canada and Poland. Seven heterozygous carriers of the HOXB13 p.Gly84Glu mutation were found in the cases (0.17 %) compared to four carriers among the controls (0.14 %; OR = 1.2, 95 % CI = 0.34-4.1, p = 1.0). Only one of the seven carriers had a family history of breast cancer. This study does not support the hypothesis that women who carry the HOXB13 Gly84Glu mutation are at increased risk of breast cancer.