Frequency of skeletal metastases in nasopharyngeal carcinoma after initiation of therapy: should bone scans be used for follow-up?

Previous reports have indicated a relatively high incidence of distant metastases in patients with nasopharyngeal carcinoma (NPC), one of the most common sites being the skeleton. Although bone scintigraphy offers the advantage of whole-body imaging in patients with cancer by providing useful information about disease spread, its value in patients with NPC is not well defined because of cost-effectiveness considerations. In this study, we assessed the value of follow-up bone scintigraphy for the evaluation of skeletal metastases in patients with different stages of NPC. Between 1994 and 2001, 230 patients with histologically proven NPC were admitted to the Department of Radiation Oncology. Out of 230 patients, 171 were examined for skeletal metastases with bone scintigraphy prior to therapy and at 1 year intervals. Bone scintigraphy detected increased uptake in 29 patients, which was reported as suggestive of metastases or equivocal. Twenty-six of these were true-positive, confirmed by radiography or clinical follow-up. Bone pain was present in 67% of these patients and serum lactate dehydrogenase and alkaline phosphatase were elevated in 35% and 37%, respectively. The incidence of bone metastases correlated with the extent of lymph node involvement, which were detected after a median time of 10.5 months following the diagnosis of the primary disease. No correlation was observed between the metastatic status and local T stage, histological differentiation age or gender of the patient. We can therefore recommend that bone scintigraphy be used in determining the presence of bone metastases, but its utilization should be preserved for those with nodal involvement.