Clinical usefulness of oral combination chemotherapy of 5′;-deoxy-5-fluorouridine (5′;-DFUR) and cyclophosphamide for metastatic Breast Cancer

BackgroundIt has been reported that 5’-deoxy-5-fluorouridine (5’-DFUR), the pro-drug of 5-FU, is effective treatment for breast cancer that express thymidine phosphorylase (dThdPase). Since oral cyclophosphamide (CPA) induces dThdPase, a synergistic effect can be expected by combining CPA with 5’-DFUR. We evaluated the usefulness of combination chemotherapy using CPA and 5’-DFUR in patients with relapsed breast cancer in this prospective phase II study.MethodsPatients with relapsed, advanced breast cancer with evaluable lesions were given 5’-DFUR at 800 mg/day/body and CPA at 100 mg/day/body for 2 weeks, then underwent 2 weeks of drug withdrawal. This was considered one course of treatment. It was repeated until progressive disease (PD) was confirmed. The lesions were evaluated according to UICC criteria and compared with regard to the clinical status.ResultsSixty-four patients with relapsed, advanced breast cancer were registered. Complete response (CR) was seen in 7 patients, partial response (PR) in 12 patients, no change (NC) in 25 patients, of whom 11 achieved long NC with the effect lasting for more than 6 months, and PD was seen in 20 patients. The response rate was 29.7%. The total number of CR, PR, and long NC cases was 30, which comprise-46.9% of the total 64 cases (the clinical benefit rate). As for adverse events, hematological toxicities were seen in 9 patients, with grade 3 toxicits was seen in 1 patient. All other adverse events were grade 1 or 2.ConclusionFor those patients who achieved an effect more than NC, it was possible to continue the therapy for an average of 53 weeks. This treatment method is worth considering for patients who have metastatic breast cancer, that is not life threatening.