Planar cobalt-57 bleomycin scintigraphy compared with CT-scan in the diagnosis and staging of lung cancer.

Objectives: Cobalt-57 bleomycin accumulates in tumour cells and is a diagnostic aid for discriminating malignant and benign lesions. Published data indicate that planar cobalt-57 bleomycin scintigraphy (bleo-scan) is a sensitive and specific test in the diagnosis and staging of lung cancer. CT-scan was however not used in these studies. We tested the value of bleo-scan and compared the results with those of computed tomography (CT-scan).
Methods: Bleo-scan and CT-scan were obtained from patients who were consecutively investigated because of a suspicious lesion on their chest X-ray.
Results: In 59 patients carcinoma of the lung was diagnosed 49 times (83%). The sensitivity of bleo-scan was 90%, specificity was 30% and positive predictive value (PPV) 86%. CT-scan could not discriminate between malignant and benign lesions. Thirty-two of the 41 patients with non-small-cell lung cancer had pathological examination of mediastinal lymph nodes, revealing metastases in 47% of the patients. Bleo-scan and CT-scan, respectively, had a sensitivity of 53 and 87%, a specificity of 77 and 82%, and negative predictive values (NPV) of 65 and 87%. In the 49 lung cancer patients distant metastases were detected at 11 sites in 10 patients. Bleo-scan gave false-negative and false-positive results.
Conclusions: Bleo-scan in (suspected) lung cancer adds too little to the diagnostic procedure to make it a routine procedure. CT-scan gives indispensable information about possible mediastinal involvement.