Cancer Types: Prostate Cancer, Bladder Cancer, Colon Cancer• The GSTM1-null genotype is associated with greater accumulation of bioactive SFN in prostate tissue, providing a pharmacokinetic basis for its enhanced efficacy in prostate cancer prevention. This genotype also correlates with a more favorable SFN metabolic profile in bladder cancer, supporting its role as a predictive biomarker.• In colon cancer, the null genotypes of GSTM1 and/or GSTT1 are linked to enhanced SFN accumulation in colonic tissue and greater efficacy in suppressing carcinogen-DNA adducts and inflammatory pathways. The gene discussed is GSTM1; the disease is urinary bladder carcinoma.