Metastatic breast cancer confined to the skeletal system. An indolent disease.

The records of 86 patients with metastatic breast cancer confined to the skeletal system were retrospectively reviewed to evaluate the clinical impression that this subset of patients with metastatic breast cancer has a favorable prognosis. The median survival for this group of patients was 48 months, compared with a median survival of 17 months in patients with breast cancer metastatic to other sites (p less than 0.01). Systemic treatment with either hormonal therapy or chemotherapy was highly effective in these patients; 56 of 64 (87 percent) showed response to the first hormonal therapy received (median, 10 months; range, four to 54 months), and 43 of 46 (93 percent) showed response to initial chemotherapy (median, 11 months; range, six to 22 months). Most patients received several therapeutic modalities sequentially; sequential responses to hormonal therapy were frequent. Orthopedic complications were common (pathologic fracture in 18; epidural spinal cord compression in 13) and occurred a median of 24 months after documentation of bone metastasis. Prolonged survival was common after these complications (median, 18 months; range, two to 48 months). The presence of metastatic disease at the time of diagnosis and premenopausal status were not adverse prognostic factors. Metastases often remained localized to the skeleton; however, appearance of extraskeletal metastasis was associated with short subsequent survival (median, nine months). Metastatic breast cancer confined to the skeletal system is a common entity that can be defined clinically, is highly responsive to treatment, and is frequently associated with prolonged survival.