adjuvant therapy

Adjuvant therapy is administered following definitive local treatment (typically surgical resection of a tumor) to eradicate micrometastatic disease that may not be detectable by imaging but is presumed to exist based on tumor stage, grade, or biology. The goal is to decrease the risk of local recurrence and distant metastasis, thereby improving disease-free survival and overall survival. Examples include: adjuvant chemotherapy (e.g., FOLFOX for stage III colon cancer, anthracycline/taxane regimens for breast cancer), adjuvant radiation therapy (e.g., after breast-conserving surgery or in high-risk head and neck cancers), adjuvant hormonal therapy (e.g., tamoxifen or aromatase inhibitors for ER+ breast cancer), and adjuvant targeted/immunotherapy (e.g., trastuzumab for HER2+ breast cancer, pembrolizumab in certain melanomas). The decision to use adjuvant therapy is based on risk stratification using tumor staging (TNM), histologic grade, molecular markers, and lymph node involvement. This contrasts with neoadjuvant therapy, which is given before surgery to shrink tumors, allow for less invasive surgery, and assess in vivo response to treatment. Both strategies are important in oncologic management and are frequently tested on boards in the context of specific cancer types (e.g., breast, colon, gastric cancers) where evidence-based guidelines dictate which patients benefit from adjuvant treatment.