ASCO Antiemetic Recommendations
For adults receiving highly emetogenic chemotherapy (HEC), use a 4-drug combination of an NK₁ receptor antagonist, 5-HT₃ receptor antagonist, dexamethasone, and olanzapine on day 1, with dexamethasone and olanzapine continued on days 2-4. 1
High Emetic Risk Chemotherapy
The 2020 ASCO guidelines provide the strongest evidence for HEC management 1:
Cisplatin and other high-emetic agents: 4-drug regimen (NK₁ + 5-HT₃ + dexamethasone + olanzapine) on day 1, continue dexamethasone and olanzapine days 2-4 (high-quality evidence, strong recommendation)
Anthracycline + cyclophosphamide: Same 4-drug combination on day 1, but only olanzapine continues days 2-4 (high-quality evidence, strong recommendation)
This represents a significant evolution from prior guidelines, as olanzapine is now standard rather than optional for HEC 1.
Moderate Emetic Risk Chemotherapy
The approach differs based on the specific agent 1:
Carboplatin AUC ≥4: 3-drug combination (NK₁ + 5-HT₃ + dexamethasone) on day 1 (high-quality evidence, strong recommendation)
Other moderate-risk agents: 2-drug combination (5-HT₃ + dexamethasone) on day 1 only (high-quality evidence, strong recommendation)
Agents causing delayed nausea (cyclophosphamide, doxorubicin, oxaliplatin): May add dexamethasone days 2-3 (low-quality evidence, moderate recommendation)
Low Emetic Risk Chemotherapy
Offer a single dose of either a 5-HT₃ receptor antagonist OR 8 mg dexamethasone before treatment 1. No prophylaxis is needed for delayed emesis 2.
Minimal Emetic Risk Chemotherapy
Do not offer routine antiemetic prophylaxis 1. This includes checkpoint inhibitors (CPIs) given alone or in combination with another CPI 1.
Critical Checkpoint Inhibitor Guidance
Adding a CPI to chemotherapy does NOT change the antiemetic regimen—base prophylaxis solely on the emetogenicity of the chemotherapy agents 1. CPIs alone are minimally emetogenic and require no routine prophylaxis 1.
Special Situations
High-Dose Chemotherapy with Stem Cell Transplant
- Standard: 3-drug combination (NK₁ + 5-HT₃ + dexamethasone) - strong recommendation 1
- Optional: Add olanzapine as 4th drug (weak recommendation, low evidence) 1
Multiday Chemotherapy
- Match antiemetics to the emetic risk of agents given each day 1
- Continue prophylaxis for 2 days after completion 1
- For 4-5 day cisplatin: Use 3-drug combination (NK₁ + 5-HT₃ + dexamethasone) throughout 1
Breakthrough Nausea/Vomiting
When prophylaxis fails, follow this algorithm 1:
- Re-evaluate: Confirm optimal regimen for emetic risk, check disease status and concurrent medications
- If olanzapine not given prophylactically: Add olanzapine to existing regimen (moderate recommendation)
- If already on olanzapine: Add a different drug class (NK₁ antagonist, benzodiazepine, dopamine antagonist, or cannabinoid) 1
Anticipatory Nausea/Vomiting
Prevention is key—use the most active regimen from the start rather than escalating after failure 1. If anticipatory emesis develops, offer behavioral therapy with systematic desensitization 1.
Adjunctive Therapies
- Lorazepam: Useful adjunct but not as monotherapy 1
- Medical marijuana: Insufficient evidence for recommendation 1
- Ginger/acupuncture: Insufficient evidence for recommendation 1
Common Pitfalls
The guidelines emphasize that nausea remains less well-controlled than vomiting and is often underestimated by clinicians 3. Continuous symptom monitoring throughout therapy is essential 3. The key to success is using the most aggressive appropriate regimen upfront rather than waiting to see if patients develop symptoms 1.