The impact of 5HT3RA antiemetics on the incidence of chemotherapy-induced nausea and vomiting (CINV), treatment adherence, and delay of therapy in early-stage breast cancer (BC) patients treated with moderately/highly emetogenic chemotherapy (MEC/HEC).

Abstract

75 Background: The effectiveness of 5-HT3receptor antagonists (5HTs) for the prevention of CINV is well established. Less is known about the impact of these drugs on chemotherapy adherence (AD) and preventing delayed therapy (DT). We examined the impact of palonosetron (PAL) vs. other 5HTs on CINV incidence, treatment AD and DT in early-stage BC. Methods: An observational nested case-control study was conducted using the HealthCore Integrated Research Database (HIRD). Female patients (pts) were identified by their first claim for IV MEC/HEC between 1/1/02 and 10/31/10 (index). Inclusion criteria were: ≥ 12 months health plan eligibility pre-index (baseline) and ≥ 6 months post-index (follow-up); ≥ 1 baseline claim for BC; no claim for secondary or multiple primary neoplasms; and ≥ 1 claim for 5HT during follow-up. CINV was defined using ICD-9 codes for nausea, vomiting, or related events, and use of rescue medications for 5 days after MEC/HEC. AD was defined as receiving the requisite number of cycles within the recommended NCCN timeframe. DT was defined as exceeding 2x the NCCN-recommended cycle length between MEC/HEC claims. Outcomes were assessed using descriptive analysis and multivariate logistic regression, controlling for demographics, baseline medical conditions, and index therapy. Results: We identified 682/696 [MEC] and 1,782/3,103 [HEC] pts who received PAL or other 5HTs, respectively. For PAL vs. 5HT, 33.7% vs. 49.7% (OR: 0.51; 95% CI 0.41-0.65; p<0.01) had CINV (mean 0.27 vs. 0.61 events/cycle) in the MEC group; in the HEC group, 27.3% vs. 35.7% (OR: 0.61; 95% CI 0.53-0.7; p<0.01) had CINV (mean 0.21 vs. 0.34 events/cycle). PAL users delayed MEC at a lower rate than those using other 5HTs (2.6% vs. 8.2%; OR: 0.37; CI 0.21-0.65; p<0.01) but had similar AD (41.8% vs. 37.2%; OR: 1.2; CI 0.95-1.5; p=0.12). No differences in AD or DT were found among pts on HEC. Conclusions: Among early-stage BC pts initiating a MEC or HEC agent, PAL was associated with fewer CINV events, a lower (MEC) or equal (HEC) rate of delayed therapy, and equal adherence compared to other 5HTs.