Comparison of survival outcomes following post-surgical radioactive iodine versus external beam radiation in stage IV differentiated thyroid carcinoma.

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Comparison of survival outcomes following post-surgical radioactive iodine versus external beam radiation in stage IV differentiated thyroid carcinoma.

Thyroid. 2017 Apr 27;:

Authors: Yang Z, Flores J, Katz S, Nathan CA, Mehta V

Abstract
<b>Background</b>: There is a lack of well-powered data regarding outcomes in stage IV differentiated thyroid carcinoma (DTC) treated with post-surgical radiation. The objective of this study is to examine survival in patients with stage IV papillary thyroid carcinoma (PTC) and follicular thyroid carcinoma (FTC) who receive radioactive iodine (RAI), external beam radiation therapy (EBRT), or neither following surgery. <b>Methods</b>: In this retrospective cohort study, data collected from the National Cancer Data Base (NCDB) yielded 11,832 patients with stage IV DTC who underwent primary surgical treatment from 2002 to 2012. Patients were stratified by histology and sub-stage. Fully parametric, multilevel survival-time models were used to evaluate survival outcomes in three adjuvant treatment groups: RAI, EBRT, or no adjuvant radiation. Hazard ratios (HR) and time ratios (TR) were calculated against patients who did not receive radiation. All models were adjusted for demographic and clinical factors. <b>Results</b>: The mean age (SD) of all patients was 61.6 years (11.6), and 57.5% were female. Patients who received EBRT had significantly higher 5- and 10-year hazards of death in several PTC sub-stages (10-year HR_{PTC Stage IV-A} = 2.12 [1.79-2.52]; HR_{PTC Stage IV-B} = 2.03 [1.33-3.10]). For stage IV-B PTC requiring EBRT, lifespan after diagnosis was shortened by a factor of 3 when compared to patients who did not receive radiation (TR_{PTC Stage IV-B} = 0.32 [0.16-0.62]). In contrast, RAI was significantly associated with improved 5- and 10-year survival in both PTC and FTC patients regardless of pathological sub-stage. Large reductions in mortality were observed in patients with FTC who were treated with RAI (HR_{FTC Stage IV-C} = 0.19 [0.06-0.65]). When patients with stage IV-C FTC were treated with RAI, lifespan after diagnosis doubled (TR_{FTC Stage IV-C} = 1.98 [1.31-3.00]). <b>Conclusions</b>: Through the NCDB, we sought to describe prognosis and survival for adjuvant radiation in stage IV DTC. RAI was associated with improved survival for stage IV DTC. Despite treatment benefits conferred by adjuvant EBRT, indications to treat with EBRT were associated with poorer survival outcomes in patients with advanced-stage DTC, particularly PTC.

PMID: 28446057 [PubMed - as supplied by publisher]

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