We are conducting three randomized studies (breast cancer, basal cell carcinoma, oral leukoplakia) and report our methodological approach and accrual here.
The aim of the breast cancer study is prevention of a contralateral primary lesion in women already treated for breast cancer; the aim of the basal cell carcinoma study is prevention of recurrences or new occurrence after surgical resection; and the aim of the oral leukoplakia study is prevention of recurrences and new occurrence after C02 laser resection. The studies were planned according to a randomized design with an intervention arm DS a no-treatment arm. Patients in the intervention group receive 4-HPR at a dose of 200 mg PO. The duration of treatment is five years in the breast cancer study, and one year in the basal cell carcinoma and oral leukoplakia studies. The breast cancer study started in March 1987, closing accrual on July 31, 1993. A total of 2,972 patients entered the study; 2,849 were evaluable (1,422 in the CHPR group and 1,427 in the control group). Of 2,849 evaluable patients, 867 completed the first five years, 1,142 are still ongoing, and 840 patients have interrupted the study for various reasons. Follow-up is ongoing. The basal cell carcinoma study started in January 1990. As of January 1994, a total of 786 patients had entered the study; 760 were evaluable (363 in the 4-HPR group and 367 in the control group). Of 760 patients in the study, 568 completed the first year, 62 are ongoing and 130 discontinued for various reasons. The study is ongoing. The oral leukoplakia study started in September 1988, closing accrual on February 1,1994. A total of 174 patients entered the study; 170 were evaluable (84 in the 4-HPR group and 86 in the control group). The preliminary data of this study have been published. Updated results as of June 1994 were 11 recurrences and three new occurrences in the 4-HPR group; the control group also had 11 recurrences, as well as 12 new occurrences. Follow-up is ongoing.