Significance of post-therapy whole body imaging with I-131 in well-differentiated thyroid cancer

ABSTRACT

Post-therapy whole body imaging with I-131 is not routinely done in the Philippines. This added cast of this procedure limits its diagnostic value for those patients who cannot afford it. This study was undertaken to evaluate the diagnostic relevance of I-131 whole body scan following therapeutic doses and its implication in further treatment and follow-up. This study included 61 patients treated in our institutions during a three-year period. Comparison of their-pre- and post-therapy who body scans was done. There were 10 males (16%) and 51 (84%) females with a mean age of 45 years + 15 (range, 17-77). Thirty three patients (54%) have corresponding pre-therapy serum thyroglobulin determination, which also guided the clinicians in the administration of appropriate therapeutic doses. The post-therapy studies were performed prior to hospital discharge . The mean interval between administration of therapy dose and imaging was 4 days (range, 2-10 days). About 34 patients (56% did not have any significant change between their pre- and post-therapy whole body scans. In 27 cases (44%), additional findings indicative of local and/or distant thyroid cancer metastasis were noted. Unsuspected cervical nodes were appreciated in 15(24%) of these cases. Seven (7) cases (11%) presented with increased metastatic deposits in the affected area. New areas of metastases were evident in 5 cases (8%). Our present data suggests that the incorporation of post-therapy whole body scans in the clinical evaluation of patients with well-differentiated thyroid cancer may help in the optimum therapeutic management and future follow-up of patients.