CINV

Chemotherapy-induced nausea and vomiting (CINV) refers to nausea and/or vomiting caused by cancer treatment. It is a common adverse effect that can affect treatment adherence and quality of life. CINV is typically categorized by timing: acute CINV occurs within 24 hours of chemotherapy; delayed CINV lasts beyond 24 hours and may continue for several days; anticipatory CINV occurs before treatment due to conditioning; breakthrough CINV happens despite prophylaxis; and refractory CINV remains uncontrolled in subsequent cycles.

The underlying mechanism involves activation of gut-derived serotonin (5-HT3) signaling and central pathways, with the substance P–neurokinin-1 (NK1) system also contributing. Risk factors include younger age, female sex, a history of motion sickness or prior CINV, and the emetogenic potential of the regimen.

Prevention and treatment are guided by the emetogenic risk of the chemotherapy. For highly emetogenic regimens, recommended prophylaxis usually combines a 5-HT3 receptor antagonist (for example, ondansetron, granisetron, or palonosetron), an NK1 receptor antagonist (such as aprepitant or fosaprepitant; some regimens use netupitant with palonosetron), and dexamethasone. Moderate risk regimens may use a 5-HT3 antagonist plus dexamethasone. Olanzapine is increasingly used as part of frontline or breakthrough regimens in some guidelines.

Management of breakthrough or refractory CINV may involve switching antiemetic classes, adjusting dosing, and adding nonpharmacologic measures such as adequate hydration and electrolyte management. Common adverse effects of antiemetics include constipation with NK1 antagonists, fatigue or somnolence with corticosteroids, and potential QT prolongation with some 5-HT3 antagonists. Guidelines from ASCO, NCCN, and MASCC inform practice.