A randomized attempt to increase the efficacy of cytotoxic chemotherapy in metastatic breast cancer by hormonal synchronization.

Human breast cancer cells in tissue culture can be growth inhibited by tamoxifen, an inhibition that can be reversed by estrogen. The question of whether tamoxifen inhibition of breast cancer followed by estradiol reversal would increase the efficacy of chemotherapy was asked. One hundred ten patients were prospectively randomized to chemotherapy consisting of cytoxan (750 mg/m2) and Adriamycin (30 mg/m2) on day 1 plus 5-fluorouracil (5-FU) (500 mg/m2) and methotrexate (MTX, 40 mg/m2) on day 8 versus the same chemotherapy plus tamoxifen (20 mg/m2) on days 2-6 and premarin (0.625 mg every 12 hours for three days) on day 7. Chemotherapy was given in 21-day cycles. The first 55 patients were randomized to a regimen in which 5-FU preceded MTX by 24 hours; thereafter, all patients received MTX followed in one hour by 5-FU. No difference in any response parameter was seen between these two 5-FU/MTX schedules. A limited number of patients with inflammatory breast cancer had a significantly higher response rate (93% versus 61%; p = 0.03) than patients with recurrent metastatic disease. Time to progression (13 versus 17 months) and survival (17 versus 23 months) of responders significantly favored the treatment arm including tamoxifen and premarin. Whereas an additive effect of hormones plus chemotherapy cannot be entirely excluded as the explanation for the improved results with the addition of tamoxifen for four days plus one day of premarin, results suggest that further efforts to increase the efficacy of chemotherapy by perturbing tumor growth rates may be worthwhile.