Background: Patients who present with unknown primary carcinomas represent 10% to 15% of the patients with cancer who present to medical centers. Despite data in the literature indicating minimal success in determining the location of primary carcinomas, these patients continue to be evaluated exhaustively. Additionally, identification of the location of primary carcinomas does not often affect treatment. Clinical treatment and prognosis are only affected if a reevaluation of the pathologic findings yields a potentially curative diagnosis of an undifferentiated lymphoma, germ cell tumor, or a hormonally sensitive carcinoma.
Methods: Tumor registry files from January 1, 1990, through December 31, 1992, were retrospectively retrieved to identify adult patients who presented with metastasis of an unknown primary site at the H. Lee Moffitt Cancer Center and Research Institute, a 162-bed tertiary care cancer center specialty hospital affiliated with the University of South Florida College of Medicine, Tampa. Medical records were reviewed for age, sex, histologic findings of previous malignant growth, types and duration of symptoms, and mode of presentation. Fifty-six of the 199 patients were included in the study; 31 were men (55.4%) and 25 were women (44.6%), with ages ranging from 33 to 83 years. Diagnostic evaluations were reviewed and included data from procedures conducted at both the H. Lee Moffitt Cancer Center and at outside facilities. Diagnostic studies performed included barium swallow; intravenous pyelogram; mammogram; abdominal ultrasound; chest x-ray film; bone scan; magnetic resonance imaging; computed tomography of the head, chest, abdomen, and pelvis; laparotomy; bronchoscopy; gastroscopy; and colonoscopy. Information for the diagnostic test procedures was taken from the point of initial patient contact until the determination of metastatic disease.
Results: The primary cancer site was found in four (7.1%) of the 56 cases in the study and could not be classified as curable by systemic means. The average cost of diagnosis was $17,973, with 19.6% of the patients surviving for more than 1 year. The mean survival period was 8.1 months. A total of 410 tests were performed with only four tests correctly identifying the location of the primary tumor.
Conclusions: Once a potentially curable malignancy has been excluded, there is little justification to support extensive diagnostic evaluation of the patient. Substantial costs are incurred and survival is often not significantly affected. It was estimated that 1.2 million new cancer cases would have occurred during 1994, with approximately 10% of these patients presenting with cancer of unknown primary origin. Based on cost assessments, investigation of these patients would exceed $1.5 billion. This clinical scenario is one where attention to outcome, clinical management, and expense should be carefully considered.