TAS-102 is primarily used in the treatment of metastatic colorectal cancer, especially in patients who have progressed on or are refractory to other standard chemotherapies. It combines a cytotoxic agent with a metabolic stabilizer to enhance efficacy. The active component exerts its effect by incorporating into DNA during replication, leading to DNA strand breaks and inhibition of tumor cell proliferation. This mechanism is particularly effective in cancers with high replication rates. TAS-102 has shown clinical benefit in improving survival and delaying disease progression in late-stage colorectal cancer. It is also being investigated for use in other solid tumors, including gastric and metastatic breast cancers, due to its targeted action and manageable safety profile. Its oral formulation offers convenience for long-term outpatient treatment, making it a valuable option in palliative and refractory settings.