<i>Conclusions</i>: Our results provide a pre-clinical rationale for the use of 6-TG in the treatment of BRCA2-deficient castration-resistant prostate cancers, and of certain 6-TG analogues for treatment of BRCA2-proficient prostate cancers.
BRCA2 mutation carriers had an increased risk of prostate cancer and a higher histologic grade, and BRCA1 or BRCA2 mutations were associated with a more aggressive clinical course.
BRCA2 mutation carriers have an increased risk of death and prostate cancer-related death [HR (95% CI) 4.5 (2.12-9.52), P = 8.9 × 10(-5)] by comparison with noncarriers.
BRCA2 carriers had an SIR of 4.45 (95% confidence interval [CI] 2.99-6.61) and absolute PCa risk of 27% (95% CI 17-41%) and 60% (95% CI 43-78%) by ages 75 and 85 yr, respectively.
A second breast cancer susceptibility gene (BRCA2) operates in some of the same molecular pathways as BRCA1, and mutations of this gene predispose to breast and ovarian cancer and probably to other tumor types, including prostate cancer.
Additional findings, regardless of TMPRSS2-ERG status, were the overrepresentation of a rare BRCA2 variant (V2728I: P = 0.03; OR, 6.16; 95% CI, 1.19-32.00) in familial PCa and of a common allele of RMI1 (variant N455S: P = 0.02; OR, 1.33; 95% CI, 1.04-1.70) in unselected PCa cases.
Although BRCA2 is probably responsible only for a very small fraction of hereditary prostate cancers, this finding supports previous reports of an increased risk of prostate cancer in BRCA2 mutation carriers.
Although multiple genes have been implicated in the development of PCa, few confer as high a risk as mutations in the genes associated with early-onset breast cancer (BRCA1 and BRCA2).
Although the increase in risk of developing breast, ovarian, and prostate cancer in BRCA1 and BRCA2 mutation carriers has been studied extensively, its impact on mortality is not well quantified.
As breast and prostate cancer share genetic risk factors, including rare, high-risk mutations (eg, in BRCA2), we hypothesized that some of these heritable methylation marks might also be associated with the risk of prostate cancer.
Association with PCa risk was statistically significant for variants in BRCA2 (P < 0.001, OR = 5.65, 95% CI = 3.55-9.32), HOXB13 (P < 0.001, OR = 4.73, 95% CI = 2.84-8.19), and ATM (P < 0.001, OR = 2.86, 95% CI = 1.63-5.15).
Blood DNA from affected individuals in 38 prostate cancer clusters was analyzed for germ-line mutations in BRCA1 and BRCA2 to assess the contribution of each of these genes to familial prostate cancer.
Chromosomal deletion is frequent at the region between BRCA2 and RB1 in the q14 band of chromosome 13 (13q14) in human cancers, including prostate cancer, suggesting the presence of a tumor suppressor gene.