Pathophysiology
Clinical meaning
Advanced oncology practice requires understanding molecular tumor profiling, targeted therapy mechanisms, and immunotherapy principles that have transformed cancer treatment. Targeted therapies exploit specific molecular alterations in cancer cells: tyrosine kinase inhibitors (imatinib for BCR-ABL in CML, erlotinib for EGFR mutations in NSCLC), monoclonal antibodies (trastuzumab targeting HER2 in breast cancer, rituximab targeting CD20 in lymphoma), and PARP inhibitors (olaparib for BRCA-mutated ovarian and breast cancers exploiting synthetic lethality). Immune checkpoint inhibitors (pembrolizumab and nivolumab targeting PD-1, ipilimumab targeting CTLA-4) restore T-cell antitumor immunity by blocking inhibitory signals that tumors exploit to evade immune destruction — immune-related adverse events (irAEs) affecting any organ system require prompt recognition and management with corticosteroids. The clinician must understand tumor mutational burden, microsatellite instability status, and PD-L1 expression as predictive biomarkers for immunotherapy response.