Surveillance after treatment for well differentiated thyroid cancer: audit for chest radiography

Well differentiated thyroid carcinoma has an excellent prognosis, with many patients achieving cure. The incidence of pulmonary metastases is about 11%. When thyroid ablation has been used in the initial treatment, serial thyroglobulin (Tg) levels are a sensitive marker of recurrent disease. Data regarding the usefulness of chest radiography (CXR) in monitoring relapse in these patients does not exist and regular CXRs continue to be performed as routine surveillance. To assess their efficacy we have reviewed all serial CXRs and corresponding Tg levels on every patient with well differentiated thyroid cancer who was treated and followed up at the Royal Marsden Hospital between 1984 and 1987. A total of 369 CXRs were performed on 49 patients, with a median follow-up of 81 months. Of these, only 15% were undertaken for a clinical reason, with 85% being requested as routine. Seven patients developed lung deposits, six of whom had CXR performed because of elevated Tg, abnormal 131I uptake imaging or thoracic symptoms. In no case were lung metastases diagnosed by routine CXR in an asymptomatic patient. The cost of routine chest films for the duration of this study was approximately 13,500 pounds. It is concluded that routine chest radiography is neither cost effective nor a sensitive method of screening for relapse in asymptomatic well differentiated thyroid cancer. It should be reserved for patients with chest symptoms, or those in whom Tg has been shown not to be a useful marker of disease.