Counting alleles in single lesions of prostate tumors from ethnically diverse patients

Abstract

The presence of racial disparities in incidence and mortality rates are well-documented for prostate cancer. Nevertheless, it is unclear whether such disparities are due to genetic alterations that are involved in prostate cancer initiation. Here, we evaluated chromosome 8p allelic loss in a racially diverse cohort. Laser-capture microdissection was used to isolate tumors cells from individual lesions in 153 prostate cancer patients, and 8p allelic status was determined by "counting alleles." Statistical analyses examined the association between pathologic predictors and biochemical recurrence. Thirty percent of prostate lesions were missing an 8p allele at tumor initiation, while 51% of lesions lost an 8p allele during tumor progression. Biochemical recurrence after radical prostatectomy could be reliably predicted by surgical margin status only in lesions with extensive 8p allelic loss. There was, however, no racial disparity in 8p allelic loss at tumor initiation or during tumor progression, suggesting that the molecular event involved was similar between Caucasians and Africa Americans (CA and AA). Nonetheless, racial differences were present in values of prognostic factors for recurrence. Gleason score was the most important predictor of recurrence (HR=3.1, 95% CI=1.1, 9.2) in AA, while among CA, pathologic stage (HR=3.3, 95% CI=1.5, 7.6) and surgical margin (HR=4.7, 95% CI=1.8, 12.6) were the most important. Therefore, racial disparity in prostate cancer may be due to other factors that are involved in prostate cancer development.