Sequential treatment of metastatic breast cancer with tamoxifen after megestrol acetate therapy and vice versa (a retrospective study).

The progestin megestrol acetate and the anti-estrogen tamoxifen are used as effective drugs in the treatment of metastatic breast cancer and have few side effects. The sequence and indications for use in practice still need to be defined. Of 219 postmenopausal patients with metastatic breast cancer and measurable lesions, 136 were treated with megestrol acetate (MA) per os (180 mg daily) and followed by tamoxifen (TAM) (40 mg daily) in cases with progression, and 83 patients were treated with the inverse drug regimen. In the first line treatment they showed similar effects: MA caused remission in 31/136 patients (23%) and TAM in 17/80 patients (22%) (mean duration 12 and 13 months respectively), while as a second treatment line MA caused remission in 14/83 patients (17%) and TAM in 12/132 patients (9%), which was not significant (P = 0.10). Also with respect to survival there was no significant difference between the two treatment modalities.