DNA Repair Capacity and Clinicopathological Characteristics in Puerto Rican Hispanic/Latino Patients with Metastatic Castration-Resistant Prostate Cancer.

Background: Prostate cancer (PCa) accounts for 22% of the new cases diagnosed in Hispanic/Latino (H/L) men in the US. PCa has the highest incidence (38.3%) and mortality (16.4%) among all types of cancer diagnosed in Puerto Rico. We previously showed that PCa patients (n = 41) have a significant reduction of 59% in their levels of DNA repair capacity (DRC) when compared to controls (n = 14). This study aimed to evaluate DRC levels through the nucleotide excision repair (NER) pathway for the first time in 16 Puerto Rican H/L men with metastatic castration-resistant PCa (mCRPCa) while establishing comparisons with controls and PCa patients with indolent and aggressive disease.

Methods: Blood samples and clinicopathological data from PCa cases (n = 71) and controls (n = 25) were evaluated. PCa cases were stratified into mCRPCa (n = 16), aggressive (n = 31), and indolent (n = 24). DRC levels through NER were measured in lymphocytes with the CometChip assay. The stratification by Gleason score (GS) was GS6 (n = 7), GS7 (n = 23), GS ≥ 8 (n = 20), and mCRPCa patients (n = 16).

Results: Significant statistical differences were found when comparing the DRC values of the controls with any other of the four PCa patient groups. mCRPCa patients had the lowest mean DRC level of all four patient groups studied. The mean DRC level of mCRPCa patients was 6.65%, and compared to the controls, this represented a statistically significant reduction of 62% (p < 0.0001). Further analysis was performed to evaluate the contributions of age, anthropometric measurements, and prostate-specific antigen (PSA) levels to the DRC. Kaplan-Meier curves of mCRPCa revealed that survival probability decreased by approximately 50% by 30 months. This pilot study uses a blood-based phenotypic assay to present the first report of mCRPCa in Puerto Rican men and at a global level of DRC levels of mCRPCa patients.

Conclusions: This study evaluated DRC levels through the NER pathway for the first time in 16 Puerto Rican H/L men with mCRPCa. Significant differences in DRC values were found between the controls and the three PCa patient groups. Kaplan-Meier curves revealed that survival probability decreased by approximately 50% by 30 months, and only 20% of the cohort was alive at 50 months, confirming the lethality of mCRPCa in this H/L population. This pilot study represents the first report of metastatic PCa in Puerto Rican men at a global level of DRC levels of mCRPCa patients using a blood-based phenotypic assay.