Could thyroid dysfunction influence outcome in sunitinib-treated metastatic renal cell carcinoma?

Background: Sunitinib is a standard of care for metastatic renal cell carcinoma (mRCC). Hypothyroidism is frequently observed under sunitinib therapy. This study was conducted to prospectively determine the correlation between thyroid function and progression-free survival (PFS) in this population. Patients and methods: One hundred and eleven mRCC patients treated with sunitinib were evaluated for serum thyroid-stimulating hormone (TSH) and T4 levels before treatment and every 6 weeks during treatment. Survival was analysed according to a landmark method with a cut-off of 6 months, excluding early progressive or early-censored patients. Results: Outofthe102patientswithnormalbaselinethyroidfunction,53%developedthyroiddysfunction,including95% hypothyroidisms out of which 90.9% received L-thyroxine replacement. Median time to TSH alteration was 5.4 months. MedianPFSwas11.7monthsfortheentirepopulation.MedianPFSwasnotdifferentbetweenthegroupswithabnormalor normal thyroid function after 6 months of treatment (18.9 and 15.9 months, respectively, log-rank P = 0.94, hazard ratio = 1.02, 95% confidence interval = 0.54‐1.93). There was no difference even after adjustment for Memorial Sloan-Kettering Cancer Centre classification and therapy line. Conclusions: Abnormal thyroid function with hormonal substitution did not increase survival in our population, independent of initial prognosis and previous treatments. Larger comparative studies are deserved to validate these