e13653 Background: The HOXB13 c.251G > A (p.G84E) variant is associated with increased prostate cancer risk, possibly at younger ages. Studies on this variant have focused primarily on men, although genetic testing for hereditary cancer risk is most often performed in women. There remains a need to assess whether male and female carriers of this variant have increased risk for other cancers. Methods: We identified male and female carriers of the HOXB13 c.251G > A (p.G84E) variant among individuals referred for hereditary cancer panel genetic testing from October 2018 – December 2019. Non-carriers had no pathogenic variants in any gene or variants of uncertain significance in HOXB13. Personal and family (1st- and 2nd-degree relative) cancer histories were obtained from provider-completed test request forms. Multivariable logistic regression (MLR) models were conducted separately for males and females to estimate cancer risks for the variant as odds ratios (ORs), and 95% Wald confidence intervals (CIs) adjusted for age, ancestry and personal/family cancer history. Results: The analysis included 197,978 patients: 4.5% (8,998/197,978) male and 95.5% (188,980/197,978) female. The HOXB13 variant was present in 0.44% (40/8,998) of tested males, 45% (18/40) of whom had a diagnosis of prostate cancer. The variant was present in 0.32% (621/188,980) of tested females. Male carriers with prostate cancer were diagnosed at younger ages (median, 56; Interquartile ratio [IQR], 52, 62) than non-carriers (median, 63; IQR, 57,70), but this difference was not statistically significant. The MLR model calculated a 3.30 OR for prostate cancer in male carriers of c.251C > A ( P = 0.01; 95% CI 1.30-8.39). In an analysis combining males and females, carriers were significantly more likely to report prostate cancer in a family member than non-carriers ( P = 3.5 x 10−7; OR 1.61, 95% CI 1.34-1.93). There was no apparent association with increased risk for other cancers among carriers versus non-carriers, or among relatives of carriers compared with relatives of non-carriers. Conclusions: The HOXB13 c.251G > A (p.G84E) variant was associated with significantly increased risk of prostate cancer, confirming previously published studies. We found no evidence of association with other cancers. For unaffected male carriers, who may frequently be identified through testing of a female relative, identification of this HOXB13 variant provides an opportunity for more precise prostate cancer risk stratification and screening.
Prediction of Breast and Prostate Cancer Risks in Male BRCA1 and BRCA2 Mutation Carriers Using Polygenic Risk Scores