Hypothyroidism, a common TKI toxicity in advanced RCC, arises from multifactorial mechanisms, including cytotoxicity to thyroid cells, thyroid peroxidase inhibition, disrupted iodine uptake, altered hormone metabolism, and reduced vascularization via VEGFR inhibition (36) The prevalence of Grade 1 and Grade 2 endocrinological toxicities in our study aligns with the lower range of reported rates, with Wu and Huang noticed a 24%-85% incidence across studies with varying methodologies (36). The gene discussed is TPO; the disease is renal cell carcinoma.