Sequential alternate administration of tamoxifen and medroxyprogesterone acetate in advanced breast cancer: clinical-biological randomized study.

From January 1985 to September 1988, 60 women with advanced breast cancer were randomized in two arms to receive: A) tamoxifen (TAM) (20 mg/die) until progression or B) TAM (20 mg/die for 14 days) then medroxyprogesterone acetate (MPA) (1500 mg/die p.o. for 14 days) followed by 7 days of wash-out before repeating the TAM/MPA treatment. All patients were post-menopausal, previously untreated with hormone therapy, and with tumor receptor status determined immediately before randomization; all had objectively evaluable lesions. In order to verify hormone receptor variations due to the antiestrogen, when possible a second biopsy was performed after the initial 14 day cycle of TAM. Thirty-one and 29 patients were included respectively in arms A and B. Objective regression (CR + PR) was observed in 58% of group A and 75% of group B, with CR in 11% and 23%, respectively. Differences were not statistically significant. Median time to progression was 12 months for group A and 9 for group B. Overall survival has not yet been reached in group A while it was 34 months for patients of group B. Metrorrhagia was observed in two cases of group A and in 6 of group B, and thrombophlebitis in 1 and 3 cases, respectively. The second biopsy confirmed a clear increase of PgR content in 8/11 cases (75%). Plasma level variations of TAM, N-desmethyl TAM and MPA were checked at various intervals on 3 patients of group B, and confirmed that our schedule is able to produce a drug wash-out period for tumor cells. In conclusion, our study demonstrated that while the manipulation of hormone receptors seems possible, results indicating better overall survival and time to progression were not obtained with alternate sequential TAM-MPA therapy.