Identifying the primary site in metastatic cancer of unknown origin. Inadequacy of roentgenographic procedures.

Two hundred sixty-six patients with metastatic nonsquamous carcinoma of unknown origin underwent upper and lower gastrointestinal series, intravenous pyelograms, and chest roentgenograms (CR) for location of a primary cancer site. Of 129 identified cancer sites, only 22 were verified antemortem, whereas necropsy disclosed 25 cases with false-positive examination results. The CR patterns thought typical for lung cancer (eg, single mass lesion and hilar or mediastinal adenopathy) were often shown (43%) to represent metastatic lesions. Because contrast roentgenographic studies are costly, uncomfortable, of low yield, and often misleading, they should be limited to cases with specific organ dysfunction.