Metastasis of unknown origin.

Evaluation of the patient with metastasis of unknown origin should be structured to quickly identify treatable tumors or the need for palliation while avoiding prolonged hospital stays and testing that will result in neither improved treatment nor better prognosis. The evaluation should be symptom-directed and pathologically oriented. It is the responsibility of the family physician in caring for a patient with MUO to ensure that communication is facilitated between surgeon, oncologist, pathologist, and patient. The physical examination should include thyroid, breasts, pelvic, and rectal examinations. General lab analyses should include fecal occult blood testing, complete blood count, urinalysis, serum calcium, and liver function studies. Men should have assays for prostate-specific antigen and serum prostatic acid phosphatase. Women should undergo mammography and pelvic ultrasound. Undifferentiated carcinoma is likely to originate from either small cell bronchogenic, lymphoma, or germ cell, and thus, serum should be assayed for HCG and AFP. Further radiologic studies, in the absence of specific symptoms, should be limited to chest radiographs and abdominal CT. Contrast studies should be included only if there is organ dysfunction. Biopsy of the malignant tissue should be done early, and studies should include histochemistry, immunohistology, and electron microscopy. Tissues from female patients should be studied for estrogen and progesterone receptors. When a biopsy is planned, advance communication between the family physician or surgeon and the pathologist greatly increases the chance of identifying a primary site. It is important that the surgeon obtain sufficient material to enable study, not only by standard histologic techniques, but also by electron microscopy, special stains, estrogen receptor activity, hormonal markers, and tumor markers. Treatment of patients for whom a primary tumor remains undiscovered must include toxic therapies only for those with good functional status who are likely to respond. Therapy must be pursued for palliation of symptoms when they develop. As physicians, we must control the urge to do something at those times when doing nothing is more appropriate. We must provide continuous support for both the patient and family, protecting to the best of our ability their quality of life. A physician should never convey the impression that it is "not cost-effective" to look for the source of a patient's malignancy. It can be emphasized that further search for a primary tumor carries both medical risk and expense, yet is unlikely to locate the primary tumor or improve the response to therapy or the quality of life.(ABSTRACT TRUNCATED AT 400 WORDS)