Well-Differentiated Thyroid Cancer: Who Should Get Postoperative Radiation?

BACKGROUND: The mainstay of treatment of well-differentiated thyroid cancer (WDTC) is surgery followed by adjuvant radioactive iodine therapy. Postoperative radiation therapy (PORT) is rarely used. OBJECTIVE: The aim of our study was to report our experience of patients with WDTC who were selected to receive PORT. MATERIALS AND METHODS: After Institutional Review Board approval, patients who received PORT were identified from a departmental database of 6259 patients with WDTC treated with primary surgery from 1986 to 2015. We carried out propensity matching to compare outcomes with a cohort of patients who did not receive PORT. The main outcome of interest was central neck recurrence-free probability (CNRFP), while secondary outcomes were lateral neck recurrence-free probability (LNRFP), disease-specific survival (DSS), and overall survival (OS). RESULTS: From 6259 patients, 32 (0.5%) patients with a median age of 65.2 years received PORT. Tall-cell variant papillary thyroid carcinoma was the most common pathology (45%). Patients who received PORT had no difference in CNRFP compared with patients treated without PORT (10-year CNRFP 88% vs. 73%; p = 0.18). Furthermore, patients who received PORT had superior LNRFP (10-year LNRFP 100% vs. 62%; p = 0.001) compared with the no-PORT cohort. Despite this, patients who received PORT had similar DSS (71% PORT vs. 75% no-PORT) and OS (65% PORT vs. 58% no-PORT group) as the no-PORT cohort. CONCLUSIONS: Our data show that select patients who received PORT had improved locoregional recurrence-free probability; however, this did not translate into improved DSS and OS. At our institution, we recommend the use of PORT only in highly selected patients with locally advanced primary tumors who are deemed to have a high risk of central neck recurrence for which salvage surgery would result in unacceptable risk to the airway.

Histologically bland "extremely well differentiated" thyroid carcinomas arising in struma ovarii can recur and metastasize.

Struma ovarii (SO) infrequently harbor carcinomas that are histologically similar to those arising in the eutopic thyroid. We identified 10 such cases in our files. Eight patients presented with pelvic-related symptoms whereas 2 were incidentally discovered during pregnancy, all with disease confined to the ovary. There were 8 papillary thyroid carcinomas (PTCs) (2 classic and 6 follicular variant) and 2 poorly differentiated thyroid carcinomas. Two of the 10 thyroid carcinomas relapsed after an initial diagnosis of "benign" struma. Both occurred in young women with ovarian cysts discovered during pregnancy. The cystectomy from 1 patient showed thyroid follicles with nuclear features of the follicular variant of PTC whereas the cyst from the second patient showed thyroid follicles with subtle nuclear features, suggestive but not diagnostic of PTC. Both patients presented with disseminated PTC 3 and 4 years after the initial diagnosis, involving the pelvis in both cases and also the liver parenchyma in 1 case. The 2 patients received radioactive iodine therapy after thyroidectomy and are both alive with disease 6 years after diagnosis. The criteria separating hyperplastic nodules from well-differentiated follicular variant of PTC in the thyroid gland seem to be applicable to thyroid-type carcinomas arising in SO. The propensity for adverse clinical behavior does not seem to be related to the grade or histologic type of carcinoma in this small series. The hormonal milieu during pregnancy may lead to progression of malignant SO and such patients should be closely followed, particularly if their treatment consists of cystectomy alone.

Targeted therapy in thyroid cancer.

PURPOSE OF REVIEW: Recent advances in the understanding of the biological basis for thyroid cancer have identified molecular changes in thyroid cancer cells. These changes form the basis for targeted therapies, which have been investigated with some success in patients with advanced, inoperable thyroid cancers and are the subject of this review. RECENT FINDINGS: For patients with advanced differentiated thyroid cancers, sorafenib, selumetinib, pazopanib and sunitinib have been investigated with promising results. In the setting of advanced medullary thyroid cancer, vandetanib now has FDA approval, whereas sorafenib, sunitinib and cabozantinib have shown activity in early studies. For patients with anaplastic thyroid cancer, no targeted therapy has been proven to be effective in vivo, although preclinical work on various kinase inhibitors has shown promise. Despite the potential for disease response, significant cardiac, gastrointestinal and skin-related side effects are reported for all therapies, limiting their application outside the setting of incurable disease. SUMMARY: Inoperable thyroid cancer still has a poor prognosis, however, the introduction of targeted therapies offers the hope of longer quality of meaningful life for this small group of patients.