Determining the site of the primary cancer in patients with skeletal metastasis of unknown origin - A retrospective study

BACKGROUND. When skeletal metastasis is the presenting problem and the prim ary site is occult, there is a need to identify the primary site as soon as possible. However, the search for the primary tumor is often time-consumin g and difficult. The purpose of this study was to analyze the efficacy of p articular diagnostic approaches and to devise an efficient and optimal diag nostic strategy. METHODS. Among 213 patients with skeletal metastasis treated between 1990 a nd 1996 were 64 in whom skeletal lesions were the first manifestation of ma lignancy. The authors retrospectively analyzed both the final diagnosis and the process by which it was made in these 64 cases. RESULTS, The primary cancer was identified antemortem in 56 (88%) of the 64 patients by examination and in 3 patients at autopsy. Lung carcinoma, the most frequently observed primary lesion, was identified in 23 patients. Oth er primary lesions were prostate carcinoma in 11 patients, breast carcinoma in 5, and hepatocellular carcinoma in 5. The primary malignancy was not de termined in 5 patients. Thoracic and abdominal computed tomography (CT) sca ns were useful, especially in the diagnosis of patients with lung, hepatoce llular, renal cell, and pancreatic carcinomas. Tumor markers were abnormall y elevated in 73% of patients with carcinomas. CONCLUSIONS, Although thoracic and abdominal CT scans were useful, examinat ion of the gastrointestinal tract and pelvic CT scan seldom revealed the pr imary lesion and therefore should not be performed as an initial routine st udy in the absence of abdominal symptoms. Tumor markers are useful in diffe rentiating carcinoma from hematologic malignancy and primary bone tumor. (C ) 1999 American Cancer Society.