Follow-up study of thyroid cancer treated by unilateral lobectomy

Abstract

c oNsr~~n4nLE uncertainty persists concerning what constitutes adequate surgical resection for differentiated carcinoma of the thyroid gland. The present discussion will be limited to the problem of surgery of the thyroid gland itself, when cancer is found grossly involving only one lobe. In recent years, the trend has been toward more extensive resection of the thyroid gland. With rare exceptions [l-3] genera1 agreement has come that anything less than total lobectomy is inadequate and not curative in this situation, because of the high incidence of residual cancer (20 per cent) found on completing the Iobectomy [4] or of stump recurrence [s;]. Beyond this point, authoritative opinion is divided among those who advocate only total lobectomy with or without resection of the isthmus [6,7], those who advocate total Iobectomy plus resection of some portion of the opposite lobe [4,8], and those who advocate total thyroidectomy [9-201. Support for use of the more extensive procedures has come from the observation of intragIandular spread or “muIticentric involvement” by cancer, reported after routine surgical pathologic examination as I I to 30 per cent involvement of the opposite lobe [8,9,12-r4,18,19,21,22]. Crile [7], however, takes the position that “the mere presence of isoIated microfoci of cancer in a lobe of the thyroid does not necessariIy mean that cancer will develop cIinicaIIy.” For the past twelve years at The University of Texas M. D. Anderson Hospital and Tumor Institute, we have been engaged in evaIuating the adequacy of these primary surgical procedures for carcinoma of the thyroid gIand. Prior to rgfo, at this institution, total lobectomy on the involved side, with or without neck dissection, was considered adequate therapy whenever there was no gross involvement of the opposite lobe. Later, when total thyroid gland resections were performed to facilitate radioiodine therapy of metastatic thyroid cancer, a significant incidence of cancer in the contraIatera1 Iobe was observed. This cast doubt on the adequacy of tota unilateral lobectomy as a curative procedure. As a result, a program for evaluating the problem was initiated whereby patients who had undergone previous “curative” lobectomy would either be submitted to prophyIactic resection of the remaining lobe or would be observed clinically on a long-term basis. A third group of patients would be treated by tota thyroidectomy as the initial surgical procedure or following previous thyroid biopsy or partial lobectomy. A corolIary project was undertaken to study the resected gland, whenever possible, by subseria1 whoIe organ sections in order to determine the mode of intraglandular dissemination and the true incidence of contralateral lobe involvement. Previous communications from this institution [g,23] have reported this dissemination to the opposite lobe in 30 per cent of glands examined by routine pathologic technics and in 84 per cent of glands submitted to subseria1 whole organ study. The present report concerns that group of patients with thyroid cancer whose initial surgical management was total lobectomy with or without neck dissection. This was then folIowed either by immediate prophylactic