Radioactive iodine does not improve overall survival for patients with aggressive variants of papillary thyroid carcinoma less than 2 cm.

BACKGROUND: Tall cell and diffuse sclerosing variants of papillary thyroid cancer are associated with aggressive features. Radioactive iodine after total thyroidectomy is poorly studied. METHODS: Patients ≥18 years in the National Cancer Data Base from 2004 to 2016 with classic papillary thyroid cancer, tall cell, or diffuse sclerosing 1 mm to 40 mm were identified. Logistic regression identified factors associated with aggressive features. Overall survival was assessed using Kaplan-Meier method and log-rank tests, after propensity score matching for clinicopathological and treatment variables. RESULTS: A total of 155,940 classic papillary thyroid cancer patients, 4,011 tall cell, and 507 diffuse sclerosing were identified. Tall cell patients represented an increasing proportion of the study population during the analysis period, whereas diffuse sclerosing and classic papillary thyroid cancer patients showed a statistically significant decline. Extrathyroidal extension and nodal involvement were more prevalent among tall cell and diffuse sclerosing patients when compared to those diagnosed with classic papillary thyroid cancer (P < .01). Adjuvant radioactive iodine was less frequently used in patients with classic papillary thyroid cancer when compared to tall cell and diffuse sclerosing patients (42.6% vs 62.4%, 59.0%; P < .001, respectively). Aggressive variants receiving total thyroidectomy versus total thyroidectomy + radioactive iodine propensity score matched across clinicopathologic variables were analyzed. There was no difference in overall survival between the 2 treatment groups for tumors <2 cm (01-1.0 cm, 92.2% vs 84.8%; P = .98); (1.0-2.0 cm, 72.7% vs 88.1%; P = .82). However, overall survival was improved for total thyroidectomy + radioactive iodine propensity score matched patients with tumor sizes 21 to 40 mm versus total thyroidectomy (83.4% vs 70.0%, P = .004). CONCLUSION: For aggressive tumor variants ≤2 cm treated with total thyroidectomy, there is no overall survival advantage provided by the addition of adjuvant radioactive iodine.

Overall survival is improved with total thyroidectomy and radiation for male patients and patients older than 55 with T2N0M0 Stage 1 classic papillary thyroid cancer.

BACKGROUND: We examine whether surgery extent and radiation administration affect overall survival for cT2N0M0 classic papillary thyroid cancer according to age and sex. METHODS: Patients with cT2N0M0 classic papillary thyroid cancer tumors in the National Cancer Data Base (2004-2016) were selected. Multivariable Cox regression analysis compared patients (combined male + female cohorts) having lobectomy to those having total thyroidectomy with or without radiation (primarily radioactive iodine) for ages: 18 to 45, 46 to 55, and >55 years. In addition, 1:1 propensity score matching and Kaplan-Meier curves with 10-year overall survival estimates, and log-rank test were stratified by age and sex. RESULTS: Lobectomy had equivalent overall survival to total thyroidectomy without and with radiation for patients (combined male + female cohorts) aged 18 to 45 and 46 to 55 years on multivariable analysis. On propensity score matching there was overall survival advantage for total thyroidectomy with radiation over both lobectomy and total thyroidectomy for men (ages 18-90+ combined) and overall survival advantage in patients (combined male + female cohort) aged >55 years having total thyroidectomy with radiation versus lobectomy. On propensity score matching there were no overall survival differences in women (ages 18-90+ combined) or patients (combined male + female cohort) aged 18 to 45 and 46 to 55 years having either lobectomy, total thyroidectomy, or total thyroidectomy with radiation. CONCLUSION: For cT2N0M0 classic papillary thyroid cancer, total thyroidectomy with radiation improves 10-year overall survival for patients (combined male + female cohort) aged >55 years and men (ages 18-90+ combined).