Polymorphisms of DNA-repair genes associated with clinical outcome in metastatic breast cancer (MBC) patients treated with gemcitabine/cisplatin (GC) (California Cancer Consortium)

675 Background: DNA repair enzymes may play an important role in determining efficacy of chemotherapy in MBC. In particular, GC combination therapy may be dependent on activity of DNA repair enzymes in host cells, since cisplatin acts by inducing DNA damage. Cancer cells with increased DNA repair capacity may be resistant to GC, and specific genes may be responsible for this increased repair capacity. We examined whether polymorphisms in genes related to DNA repair were associated with clinical outcome in MBC patients treated with GC, enrolled in a parent phase II clinical trial (Ph II-14 A & B). Methods: Fifty-five patients with MBC were evaluated. Patients received the following regimen: 25 mg/m2 cisplatin on days 1–4; 1000 mg/m2 gemcitabine on days 2 and 8 of 21-day cycle. Thirteen polymorphisms in 10 cancer-related genes were tested for association with overall survival, time to tumor progression, and tumor response using a PCR RFLP based assay. Results: Of 55 patients evaluated, there were 17 respond...