Introduction: Skin cancer and prostate cancer (PC) are the two most cancers in men. Some data suggest sun exposure and Vitamin D levels inversely correlate with PC. We tested the association between pre-surgery skin cancer presence and outcomes after radical prostatectomy (RP) for PC in a large multi-center cohort. Methods: We retrospectively reviewed data from men treated by RP from 1988-2020 at 9 VA hospitals. We excluded Black (n=2,743), other (n=299), and missing (n=69) race as skin cancers in these groups was very low. Men were segregated as melanoma, non-melanoma, and no skin cancer. Baseline features across groups were compared. Cox models were used to test the association between skin cancer groups and biochemical recurrence (BCR), metastasis, and castration resistant PC (CRPC). For PC specific mortality (PCSM), competing risk models were used to account for death from other causes. Results: 6,817 men met inclusion: 557 had skin cancer (497 non-melanoma; 60 melanoma). Men with skin cancer were older (median 67 vs 65 yrs), had surgery more recently (median 2011-2 vs. 2006), were slightly less likely to have cT2, and more likely to have grade group 3-5 than men without skin cancer (all p<0.05). On univariable analyses, non-melanoma was unrelated to BCR, metastasis, and CRPC (HRs 0.98-1.05; all p>0.1) (table). Melanoma was linked with numerically fewer poor outcomes (HR 0.46-0.75 and not calculable for PCSM due to no events), though none of these associations were significant. On multivariable analyses, the null associations between non-melanoma and outcomes remained, though all HRs were <1 (0.79-0.94). For melanoma, all HRs remained in the direction of lower risk (HRs 0.16-0.73), though results were not significant (table). Conclusions: Our results suggest presence of non-melanoma skin cancer is unrelated to PC outcomes after RP, though a very modest association cannot be ruled out. While the numeric direction of reduced aggressiveness (all HRs <1) is in line with our hypothesis that Vitamin D levels associated with sun exposure may reduce PC aggressiveness, the lack of significance suggests any effects, if real, are modest at best. Alternatively, the more strongly, but still null, inverse associations with melanoma warrants further study given our sample only included 60 men with melanoma. SOURCE OF Funding: .
