摘要：

It has been observed by DeGroot and colleagues (1) that the mortality from follicular thyroid carcinoma may be double that of the papillary variety of cancer with death at a younger age. The poor prognosis, particularly in men over age 45 with initial tumors larger than 2.5 cm led these workers to propose that measures more vigorous than simply thyroidectomy followed by radioiodine should be considered, to include external radiotherapy and prophylactic chemotherapy. There are limitations, however, even in the efficacy of external megavoltage irradiation in the management of follicular thyroid carcinomas just as was described earlier in this volume for papillary carcinoma. In general, follicular tumors are less radiosensitive than papillary or mixed papillary-follicular tumors (2) . External megavoltage radiation has its greatest application to follicular tumors which have lost their ability to accumulate radioiodine but it can also be used as an adjunct to supplement the effects of radioactive iodine. A general review of the use of external radiation therapy for the treatment of thyroid cancer has appeared recently (3) . The same group reported on their success with radioiodine and external radiotherapy in 382 patients with differentiated thyroid cancer, of whom 120 had follicular carcinoma (4) . It is often difficult to assess the responses to radiation therapy when the patients selected to receive such therapy are often those with the most extensive disease. This was the case in the latter study, in which the use of external radiation was associated with the most advanced local disease. Notwithstanding this caveat and after adjustment for prognostic factors, there was no significant difference in cause specific survival from the cancer between patients who received external radiation and those who did not. Patients with either residual microscopic or macroscopic papillary carcinoma tended to do better than the patients with follicular carcinoma (4) . Similar results were seen in a retrospective analysis by Lin and associates (5) of 72 patients with differentiated cancer who received external radiation therapy postoperatively. While radiation therapy appeared to cause temporary tumor regression, no significant effect was seen in survival rate.

展开