Prognostic significance of the number of bone scan abnormalities at the time of initial bone metastatic recurrence in breast carcinoma

BACKGROUND: To gain insight into the factors that contribute to the more favorable prognosis associated with recurrence limited to bone in patients with breast carcinoma, the authors analyzed the number of sites of initial involvement identified on radionuclide bone scans in relation to long term outcome. METHODS: Records of 641 patients with clinical Stage I-III breast carcinoma that originally was diagnosed in 1974-1985 were reviewed. During follow-up, 295 patients (46%) experienced distant recurrence, including 116 with bone as the sole initial site of metastatic disease. Radionuclide bone scans identified the initial site(s) of recurrence in 113 of these latter 116 patients, and these studies were categorized by the number of skeletal lesions subsequently confirmed as metastases (1, 2, or > or = 3). Survival from time of recurrence and time of original diagnosis was analyzed using Kaplan-Meier methods, and factors associated with recurrence and mortality were examined using logistic and Cox regression. RESULTS: Median survival from time of recurrence was 35 months in the patients with bone-only metastases, compared with 11-26 months for all other sites of visceral recurrence exclusive of bone. Number of positive lymph nodes and estrogen receptor status were the only predictive variables for recurrence. Median survival from time of recurrence and time of original diagnosis for the 3 bone scan categories was: 1 lesion (n = 47), 53 and 86 months; 2 lesions (n = 22), 38 and 68 months; and > or = 3 lesions (n = 44), 22 and 58 months (P or = 3). In the "bone-only" group, the number of scan lesions was the strongest predictor of length of survival. CONCLUSIONS: Patients with breast carcinoma who experience a recurrence in bone at only one or two sites initially have a survival advantage over those with more extensive (> or = 3 sites) skeletal metastases and those with metastatic disease involving other visceral organs.