Four hundred thirty-eight patients with metastatic breast cancer treated with nine prospective randomized trials were reviewed to analyze, characterize, and compare those with complete regression (CR) (N=49 [11%]) with those with noncomplete regression (non-CR) (N=389 [89%]). Site of dominant disease was identical in the CR and non-CR patients. However, CR was statistically more likely when the disease-free interval and the postmenopausal status was five years or less. Survival and time to progression were statistically similar for osseous, visceral, and soft-tissue-dominant disease. Relapses generally occurred at sites of prior dominant disease, except that relapses occurred in the CNS in 14%. Six CR patients received prolonged chemotherapy and were believed to be "cured" when treatment was discontinued; however, all except one have had relapses. (JAMA242:2075-2079, 1979)