Small cell lung cancer: radionuclide bone scans for assessment of tumor extent and response

Radionuclide bone scans were performed before and during combination chemotherapy in 119 systematically staged patients with small cell carcinoma of the lung. Before therapy, 49 patients (41%) had positive scans. Scan positivity was significantly associated with the presence of metastatic tumor in the bone marrow, positive skeletal radiographs, and elevated serum alkaline phosphatase levels. Nonosseous distant metastases were significantly more likely to be detected as the number of areas of focal abnormalities on bone scan increased. The survival of patients with documented distant metastases in bone and nonosseous sites was significantly inferior to the survival of patients with limited disease, isolated osseous extensive disease, and extensive disease occurring only in nonbony sites. Of 36 patients with initially abnormal scans and tumor regression documented by other methods, scan findings improved in 24 (67%). In 26 (36%) of 72 scans in patients demonstrating disease progression in extraosseous sites, new areas of increased radionuclide uptake appeared. Improvement or worsening in follow-up scans was associated with nonbony tumor response or progression, respectively, 70% of the time. Serial bone scans provide reasonably accurate staging and prognostic information in patients with small cell lung cancer, although they are probably not sufficiently reliable to be used as the sole parameter in therapeutic decision-making.