Real-World Outcomes of Fosaprepitant-Containing Prophylaxis in Patients Receiving Highly and Moderately Emetogenic Chemotherapy: A Two-Center Retrospective Study.

Objectives: This study aimed to evaluate the efficacy and safety of fosaprepitant-containing antiemetic prophylaxis and associated patient-related risk factors in patients receiving highly emetogenic chemotherapy (HEC) and moderately emetogenic chemotherapy (MEC). Methods: Medical records of patients treated between July 2021 and March 2022 at two oncology centers were retrospectively reviewed. A total of 50 adult patients receiving chemotherapy were included in the study. The antiemetic regimen consisted of fosaprepitant, dexamethasone, granisetron, and olanzapine. Demographic data, emetogenic risk classification, Beck Anxiety Inventory (BAI) scores, timing and frequency of nausea and vomiting according to NCI-CTCAE v5.0, the need for rescue antiemetics, and adverse events were evaluated. The primary endpoint was defined as complete response (no vomiting) within 0-120 hours. Statistical analyses were performed using Fisher's exact test. Results: The majority of patients were female (80%) and younger than 65 years (84%). The most frequent diagnoses were breast cancer (38%) and pancreatic-biliary cancers (18%). All patients with comorbidities were in remission. A history of hyperemesis gravidarum was reported in 22% of patients, motion sickness in 18%, and alcohol use in 18%. Based on BAI scores, moderate and severe anxiety were detected in 16% and 2% of patients, respectively. According to the emetogenic risk classification, 82% of patients received HEC and 18% received MEC. Complete vomiting control was achieved in 80% of patients receiving fosaprepitant therapy, whereas 48% experienced no nausea. No statistically significant associations were found between emetogenic risk group, anxiety level, alcohol use, history of hyperemesis gravidarum, or motion sickness and treatment response (p>0.05). Complete response rates were 85.4% in the HEC group and 55.6% in the MEC group (p=0.118). Although the complete response rate was lower in patients with clinically significant anxiety (66.7%) than in those with low anxiety (82.4%), the difference was not statistically significant (p=0.475). Rescue antiemetics were required in 52% of patients. The most common adverse events were fatigue (10%) and dyspepsia (4%). Conclusion: In this real-world study, high rates of vomiting control were observed with fosaprepitant-based antiemetic therapy. The treatment was generally well tolerated. Although not statistically significant, the lower response rates observed in patients receiving MEC regimens and those with high anxiety levels suggest the need for more vigilant monitoring in these patient subgroups.