The prevalence of the AR-V7 variant and its association with clinicopathologic characteristics in non-prostatic cancers-a systematic review.

Androgen receptor splice variant 7 (AR-V7) is associated with resistance to androgen receptor-targeting therapies in prostate cancer, but its prevalence and clinical relevance in non-prostatic cancers remain incompletely characterized. A systematic review was conducted in accordance with PRISMA guidelines. Thirty-four studies, including 4855 clinical cases and 60 cell lines, were included. Overall, AR-V7 positivity was reported in 948/4855 clinical cases (19.5%); however, this represents a descriptive estimate across heterogeneous tumor types, study designs, and detection methods. Breast cancer accounted for 4057 of 4855 clinical cases (83.6%) and 815 of 948 AR-V7-positive cases (86.0%), with a within-cancer prevalence of 20.1%. However, after excluding the TCGA cohort in which AR-V7 was inferred through splice-junction analysis, the prevalence of AR-V7-positive breast cancer decreased to 9%. Higher tumor-specific proportions were observed in salivary duct carcinoma (55.2%), hepatocellular carcinoma (57.1%), and non-muscle-invasive bladder cancer (82.6%), but these estimates were based on smaller cohorts and should be interpreted cautiously. AR-V7 was present in several treatment-naive non-prostatic cancers, suggesting that it may represent a preexisting molecular feature in selected contexts. Current evidence suggests that AR-V7 warrants further investigation as a candidate biomarker. Standardized detection methods and prospective studies are needed before its clinical utility can be established.