Sunitinib is primarily used in the treatment of various types of cancers. It is particularly effective in managing advanced renal cell carcinoma (kidney cancer), gastrointestinal stromal tumors (GIST) that are resistant to other treatments, and pancreatic neuroendocrine tumors. The drug works by inhibiting multiple receptor tyrosine kinases, which are involved in tumor growth, angiogenesis, and metastasis. By blocking these pathways, sunitinib helps to slow down or stop the progression of cancer, improving patient outcomes and survival rates. It is typically administered orally, allowing for convenient outpatient treatment. Regular monitoring is required to manage potential side effects, such as hypertension, fatigue, and gastrointestinal issues.