Exploring unmet needs in radiation-induced nausea and vomiting after moderately emetogenic treatment.

12124 Background: Despite their prevalence and clinical significance, interventions to improve radiation-induced nausea and vomiting (RINV) are insufficiently researched and prioritized. The 2020 ASCO Antiemetic guidelines categorize craniospinal radiation therapy (RT) as a moderate risk for RINV requiring 5HT3-RA prophylaxis +/- dexamethasone. Yet, RINV guideline implementation and associated clinical outcomes remain poorly characterized. Methods: We performed a retrospective analysis at an NCI-designated comprehensive cancer center. Our primary aim was to determine the proportion of adult patients with guideline-concordant antiemetics prescribed prior to craniospinal RT between 06/2020-10/2023. Patients were excluded if they received concurrent chemotherapy. We selected the first eligible RT regimen. Secondary aims included determining the proportion of consult notes documenting RINV risk, patient report of RINV, and correlating RINV with clinical variables using logistic regression. Results: A total of 212 patients met inclusion criteria, with a median age of 67 and 37% were female. The most common malignancies were prostate (27%), breast (14%), and lung (11%). At the start of RT, 44% had a prescription for a 5HT3-RA and 42% had dexamethasone prescribed for pain and/or edema. 41% of radiation oncology consult notes documented RINV as a risk of RT. Overall, 39% of patients reported RINV during or up to 10 days after RT. An increased risk of RINV was associated with a documented history of prior chemotherapy-induced nausea and vomiting (CINV; OR 2.50, p=0.017), younger age (OR 2.28, p=0.018), and a 5HT3-RA prescription prior to the start of RT (OR 1.76, p=0.047). There was no association between RINV and sex, prior chemotherapy, dexamethasone, or 5HT3-RA/dexamethasone combination at the start of RT. Conclusions: Despite the prevalence of RINV, standardized prophylaxis remains suboptimal for patients receiving craniospinal RT. A key opportunity exists to enhance patient outcomes by conducting prospective interventional studies to address this unmet clinical need. Outcome: RINV (yes vs. no) Patient Characteristics Categories N (%) Odds Ratio (95% CI) p-value Sex Male^Female 133 (62.7)79 (37.3) 1.46 (0.82-2.57) 0.196 Age ≥55 yo^<55 yo 170 (80.2)42 (19.8) 2.28 (1.15-4.56) 0.018 Prior exposure to chemotherapy No^Yes 124 (58.5)88 (41.5) 1.08 (0.62-1.89) 0.783 Documented history of CINV No^Yes 179 (84.4)33 (15.6) 2.50 (1.18-5.41) 0.017 5HT3-RA at RT start No^Yes 119 (56.1)93 (43.9) 1.76 (1.01-3.10) 0.047 Dexamethasone (pain, edema) at RT start No^Yes 123 (58.0)89 (42.0) 0.75 (0.43-1.32) 0.328 5HT3-RA + dexamethasone at RT start No^Yes 169 (79.7)43 (20.3) 0.92 (0.46-1.83) 0.825 ^Reference level for logistic regression odds ratio (odds of RINV).