Comparing outcomes in poorly-differentiated versus anaplastic thyroid cancers treated with radiation: a surveillance, epidemiology, and end results analysis.

Abstract

Poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC) are considered the most aggressive cancers of the head and neck. The aim of the study was to evaluate and compare survival outcomes in PDTC and ATC in a large population-based cohort. Patients with PDTC and ATC diagnosed from 1973 to 2008 were obtained from Surveillance, Epidemiology, and End RESULTS database. Kaplan-Meier survival analysis and log-rank analyses were performed to evaluate (1) The effect of histology on cause-specific survival (CSS) and (2) the influence of factors such as treatment, treatment sequence, race, sex, and age on CSS. Multivariate analysis was performed to assess the independent effect of these factors on CSS. A total of 1352 patients with PDTC and ATC were identified. PDTC constituted 52.4% of patients versus 47.6% for ATC. Median CSS was similar in the two histology groups (P = 0.14). Both PDTC and ATC patients receiving radioisotopes showed a significantly better CSS compared to external beam radiation (P < 0.0001). PDTC and ATC Patients receiving radiation prior to surgery demonstrated a significantly lower CSS compared to patients receiving radiation postoperatively (P < 0.0001). Female gender and black/nonwhite race tended to improve CSS in PDTC and ATC patients (P = 0.29 and P = 0.03, for gender and race, respectively). However, multivariate analysis revealed only type of radiation treatment and age to be independently associated with CSS. This is the first large population-based study evaluating PDTC and ATC outcomes in patients who received radiation treatment. Radioisotope use and timing of radiotherapy (postoperative vs. preoperative) were associated with improved CSS in both histologies.