Hypothyroidism and its impact on outcomes in head and neck cancer.
e24066 Background: Hypothyroidism is a known late side effect of chemo-radiation in head and neck cancer. Hypothyroidism has been known to be associated with improved outcomes in renal cell carcinoma. Whether such a phenomenon exists in head and neck cancer is unknown. Methods: We performed a phase 3 study evaluating the role of Nimotuzumab in head and neck squamous cell cancers (HNSCC). In this study adult HNSCC patients treated with Cisplatin and radiation were randomly assigned to receive Nimotuzumab or not. The data of this study has been utilized for this analysis. Hypothyroidism was defined as TSH level more than 4.95 U/L. The cumulative incidence of hypothyroidism and its impact on PFS (progression free survival), OS (overall survival) and loco-regional control (LRC) was evaluated using binary regression analysis. To study the impact of hypothyroidism in outcomes a landmark analysis was performed. Results: 176/536 patients analyzed developed hypothyroidism with a cumulative incidence of 33%. Hypothyroidism showed a favorable impact on PFS, OS and LRC. Median PFS was 19.5 months while median OS was 22.2 months in the euthyroid subgroup vs not reached (NR) for both in the hypothyroid subgroup. The respective hazard rates (HR) for PFS and OS was 0.37 (95% CI: 0.27 - 0.52) and 0.15 (95% CI: 0.11 - 0.23). The LRC was also better with its median duration being 39.2 months vs NR in the euthyroid and hypothyroid subgroups respectively; HR for LRC being 0.40 (95% CI: 0.28 - 0.58). Conclusions: Thus development of hypothyroidism is associated with improved outcomes in HNSCC in terms of LRC and survival.