Sorafenib use in patients with radioiodine-refractory differentiated thyroid cancer - A five-year experience at the ISSSTE National Medical Center 20 de Noviembre in Mexico City

Abstract

Background: Sorafenib was the first oral multikinase inhibitor to be approved for the treatment of patients with locally advanced or metastatic radioactive iodine-refractory differentiated thyroid cancer (DTC). The impact of this treatment is not known in the Mexican population. Method: A retrospective, observational study was carried out by reviewing 31 electronic medical records of conventional treatment-refractory patients with DTC who were treated with sorafenib within the period from January 2013 to January 2018. Results: A total of 31 patients met the inclusion criteria, with a higher frequency in women (71%), with a history of papillary DTC in 93.5%, histologic Grade I in 83.9%, and presence of vascular permeation in 67.7%. The majority of patients presented an Eastern Cooperative Oncology Group 1 at the onset of treatment (83.9%), and the most common site of metastasis was the lung in 64.5% of cases. The subjects had been previously treated with surgery (87.1%), radioiodine (74.2%), and radiotherapy (41.9%). Based on response criteria (lesion size reduction, basal thyroglobulin decrease, progression-free interval increase, tumor-associated symptoms decrease), stable disease was observed in 74.2% and an overall response rate of 25.8%. Mean progression-free survival (PFS) was 16.13 months, with a standard deviation of 2.15 months. Sorafenib was initiated at a dose of 800 mg/day, and in 30 patients (96.77%), the dose was reduced to 600 mg/day due to the presence of Grade 2 palmar-plantar erythrodysesthesia, with a mean reduction time of 11.6 weeks and, subsequently, 24 patients (80%) underwent a second dose reduction to 400 mg/day due to the presence of Grade 3 asthenia. Conclusions: Sorafenib increased PFS, lowered thyroglobulin levels, reduced tumor size, and decreased tumor-associated symptoms in patients with locally advanced or metastatic DTC who were refractory to standard treatment. In Mexican population, due to the toxicity that occurred in the patients, the dose reduction was performed in more than half of the patients.