[External irradiation of differentiated thyroid cancer: 30 follow up]

Following surgery which left no macroscopic residue 114 patients with differentiated thyroid cancer (58 papillary, 56 follicular) were subgrouped on the basis of the dose of prophylactic postoperative external radiation applied: group I--an adequate dose of radiation (greater than or equal to 4500 cGy of telecobalt, greater than or equal to 4000 R of orthovolt therapy); group II--an inadequate dose of radiation (including non-irradiated patients). Local/regional relapse-free survival (LRRFS), distant metastatic relapse-free survival (DMRFS) and total cause-specific survival (TCSS) were calculated by means of life-table analysis for both histologic types separately. Results. 1. TCSS and LRRFS were significantly (p less than 0.001) better for group I in papillary cancer. No difference was found in DMRFS. 2. LRRFS was significantly (p less than 0.001) better for group I in follicular cancer. No differences were found in TCSS and DMRFS.

1. The prophylactic postoperative external irradiation is an effective method for survival prolongation in papillary cancer, the local/regional recurrences thereby being reduced. 2. External irradiation, in conjunction with radioiodine treatment, should be considered in the postoperative management of follicular cancer to diminish local/regional relapse.