The aim of the study was to evaluate the diagnostic value of nuclear matrix protein 22 (NMP22) and bladder-specific proteins (BLCA-4) in BC patients with genetic predisposition (NAT2 genotype) and with DNA damage measured by 8-hydroxy-2′-deoxyguanosine (8-OHdG) level, as well as detoxification by isoenzyme GSTπ level in the urine. The gene discussed is NUMA1; the disease is breast cancer.