Postoperative 5-fluorouracil plus levamisole combined with radiation therapy for high risk rectal cancer patients

Adjuvant chemotherapy in rectal cancer patients is aimed at decreasing the relapse rate of the disease, increasing the disease-free and the overall survival of the patients. The combinations of radiation therapy and several drugs have been tested, but the efficacy of 5-fluorouracil plus levamisole in rectal cancer is not determined yet. Sixty-two consecutive Dukes' B2 or C rectal cancer patients were enrolled into a prospective phase II study. Within 4 to 6 weeks following en-block resection of the tumor and lymphatics, adjuvant chemotherapy had to be started. Combination of 5-FU 375 mg/m(2)/day was given intravenously over 15-20 min for 5 consecutive days, every 4 weeks for 1 year. Levamisole 50 mg t.i.d. was administered orally during the first 3 days of each course of chemotherapy. Radiation therapy included 50 Gy, given by a linear accelerator 8 MV, to a pelvic BOX field. Dose per fraction was 1.8-2.0 Gy daily, administered for 5 consecutive days a week. Follow-up time of the whole group ranges from 7 to 53 months (median 18). Failure rate was 32.3%. The most common site for first relapse was the liver followed by recurrence in the pelvis or the surgical bed. Age, sex, tumor grade and number of involved lymph nodes were not associated with rate nor with site of relapse. Fifty-five percent of the relapses were observed in patients during the year of the adjuvant treatment. Toxicity included diarrhea (33.9%), nausea and vomiting (19.4%), weakness and mucositis. The disease-free survival rate for a median follow-up of 18 months in our study is 75%. The 3.5 year disease-free survival is 67% for the whole group. Our phase II study results point to the feasibility and acceptable toxicity of post-operative combination of 5-FU plus low-dose levamisole and radiation therapy in rectal cancer patients.