RT Journal Article SR Electronic T1 Investigation of Regorafenib-induced Hypothyroidism in Patients with Metastatic Colorectal Cancer JF Anticancer Research JO Anticancer Res FD International Institute of Anticancer Research SP 4059 OP 4062 VO 35 IS 7 A1 KAZUO SUGITA A1 KAZUYOSHI KAWAKAMI A1 TAKASHI YOKOKAWA A1 YUTARO MAE A1 WATARU TOYA A1 AKANE HAGINO A1 KENICHI SUZUKI A1 MITSUKUNI SUENAGA A1 NOBUYUKI MIZUNUMA A1 TOSHIHARU YAMAGUCHI A1 TOSHIHIRO HAMA YR 2015 UL http://ar.iiarjournals.org/content/35/7/4059.abstract AB Hypothyroidism is one of the side-effects caused by regorafenib. In the Japanese subset of the CORRECT study, hypothyroidism developed in 1.5% of the patients, but was not grade 3 or higher in any patient. Regorafenib is an oral multi-kinase inhibitor that has the same mechanism of action as sunitinb. However, the reported incidence of sunitinb-related hypothyroidism varies widely, ranging from 16.0% in clinical trials to 35.4% in post-marketing surveillance studies. In general, symptoms of hypothyroidism include fatigue and dysphonia. Hyperthyroidism must, therefore, be appropriately managed in order to maintain patient quality of life and avoid a critical level of hypothyroidism. During the first cycle of treatment with regorafenib, the incidence of abnormal thyroid-stimulating hormone (TSH) elevation was 31.4%. Our results suggest that thyroid function tests should be performed from day 1 of treatment with regorafenib. It would be prudent to consider routine monitoring of thyroid function in all patients who receive regorafenib and to recommend endocrinological consultation as necessary.