In pursuit of the unknown primary.

The case histories of sixty-seven patients were reviewed to evaluate the contribution made by various x-ray and laboratory studies to the diagnosis and treatment of systemic metastases from unknown primary tumors. When used as screening procedures, radiographic contrast studies were rarely helpful unless the test was indicated by appropriate symptoms. The large number (8 of 27) of misleading ultrasonic scans rendered that study a major source of confusion. Inadequate tissue samples were another cause of confusion and delay. Even with adequate tissue samples, a definitive pathologic diagnosis could be assigned to only forty-five of the sixty-five patients who underwent biopsy. After extensive diagnostic evaluations, only thirty-one of the sixty-seven patients received chemotherapy for specific diagnoses. Objective remissions were seen in four of thirty-one recipients of specific chemotherapy and one of five patients treated without a primary diagnosis. The same patients would have received the same therapy had the diagnostic workup been limited to x-ray studies of symptomatic systems, adequate tissue sampling, and appropriate pathologic examinations followed by treatment of the "most treatable" disease.