57Co-bleomycin and 67Ga-citrate in detecting and staging lung cancer.

Abstract
In the investigation of suspected lung cancer bleomycin labeled with cobalt-57 and gallium-67 labeled with citrate are currently used to detect the primary tumor, and to establish the presence of metastases in the lung hilum and mediastinum. A comparative study of these radiopharmaceuticals was performed in 63 patients with proved lung cancer. 57Co-bleomycin showed the primary tumor in 58 patients (92%) and 67Ga-citrate in 34 (54%) (P < 0.01). The average tumor-to-lung ratio was 3.4 with 57Co-bleomycin and 1.5 with 67Ga-citrate. Proved metastases in the hilum or the mediastinum were visualized with 57Co-bleomycin scintigraphy in 16 out of 18 patients (89%) and with 67Ga-citrate scintigraphy in only 8 (45%) (P < 0.01). 57Co-bleomycin scintigraphy is more suitable for detecting and staging lung cancer than is 67Ga-citrate. 57Co-bleomycin is valuable in the detection of peripheral lesions, in which a pathological diagnosis is difficult to achieve, since a positive scintigram indicates malignancy. When 57Co-bleomycin scintigraphy suggests hilar or mediastinal metastases mediastinoscopy should be carried out; but when no metastases are apparent it is reasonable to proceed directly to thoracotomy without mediastinoscopy.