A comparison of cobalt (57Co) bleomycin scanning and contrast-enhanced CT scanning for assessment of the mediastinum in lung cancer.

Sixty patients with histologically proven lung cancer who had been accepted for mediastinoscopy or thoracotomy were prospectively entered into a study to evaluate computed tomographic (CT) scanning, 57Co-bleomycin scanning, and barium swallow in preoperative assessment of mediastinal lymph node metastasis. Fifty-six patients had thoracotomy at which all accessible lymph nodes were sampled. Twenty-four patients were found to have mediastinal tumor on histologic analysis of the resected mediastinal lymph nodes. Neither 57Co-bleomycin scanning nor barium swallow were clinically useful, with sensitivities of 21 percent and 11 percent respectively, whereas CT scanning was helpful. However, there was no clear cutoff point of node size to optimize sensitivity and specificity for CT scanning. When nodes greater than or equal to 15 mm were taken to indicate likely malignancy, the sensitivity was 58 percent and the specificity was 87 percent and when greater than or equal to 10 mm was used the sensitivity was 80 percent but the specificity was only 55 percent. There was no clear relationship between the size of the largest resected lymph node in each patient and the presence of malignant lymph nodes. Only 42 percent of patients with resected nodes greater than or equal to 2 cm had histologic evidence of metastases. We conclude that CT scanning should be used to indicate the presence and site of mediastinal lymph nodes, which, when visualized, should always be sampled and histologically examined prior to resection of primary tumor.