Abstract 462P
Background
Retrospective analyses suggest that anti-EGFR therapy (panitumumab or cetuximab) may be superior to bevacizumab when added to first-line (1L) chemotherapy in patients with metastatic colorectal cancer (mCRC) who have left sided primary tumors (LSPT). In this study we evaluated trends in the management of left sided, RAS/RAF wild type (WT) mCRC in the United States (US) and compared clinical outcomes among the most commonly used treatment strategies.
Methods
The nationwide Flatiron Health EHR-derived de-identified database was reviewed for patients diagnosed with mCRC between 2013 and 2018. Patients who were RAS/RAF WT and had a LSPT determined by ICD coding were included for analysis. Treatment trends over time were visually assessed. Kaplan-Meier and Cox proportional hazards modeling were used to compare survival outcomes stratified by 1L therapy. Models were adjusted for chemotherapy backbone, primary tumor site, age, gender, stage at diagnosis, mismatch repair status, and performance status.
Results
Out of 9,753 patients with mCRC, 1,607 were reported as left sided, RAS/RAF WT. Of these, 456 (28%) received 1L chemotherapy alone, 965 (60%) chemotherapy plus bevacizumab, and 186 (12%) chemotherapy plus an anti-EGFR agent. A visual trend over time in these percentages was not observed. Median overall survival for patients treated with an anti-EGFR agent was 42.9 months (mo) (95% CI 36.0 – not reached) compared to 27.5 mo for those treated with bevacizumab (95% CI 25.8 – 28.9), and 27.3 mo for those treated with chemotherapy alone (95% CI 24.8 – 32.3) (p = 0.0018). Compared to chemotherapy alone, multivariate analysis showed an improvement in survival with the addition of an anti-EGFR agent (HR 0.52, 95% CI 0.33 – 0.82, p = 0.005) but not bevacizumab (HR 0.88, 95% CI 0.68 – 1.14, p = 0.33).
Conclusions
This analysis of real-world data showed no clear trend over time in the management of patients with left sided, RAS/RAF WT mCRC. Chemotherapy with bevacizumab remains the most widely used 1L treatment strategy in the US. Despite this preference, our analysis suggests that survival outcomes may be superior with the addition of a 1L anti-EGFR agent. Prospective trials are needed to clarify the optimal treatment strategy for these patients.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
National Cancer Institute (P30CA042014-23).
Disclosure
B. Haaland: Advisory/Consultancy: Prometics Life Sciences; Travel/Accommodation/Expenses: Flatiron Health; Advisory/Consultancy: Astra Zeneca; Advisory/Consultancy: Value Analytics; Advisory/Consultancy: National Kidney Foundation. I. Garrido-Laguna: Advisory/Consultancy: Ignyta; Advisory/Consultancy: Array; Advisory/Consultancy: Glycyx. All other authors have declared no conflicts of interest.