EP228 - Surgery continues to be associated with survival benefit in metastatic colorectal cancer: A contemporary analysis of national treatment patterns

Purpose/Background: Surgical management of metastatic colorectal cancer (mCRC) has evolved in recent decades with improving systemic and non-surgical locoregional therapies. Multiple recent trials have advocated against resection of asymptomatic primary disease. However, historically patients who undergo either primary tumor resection (PTR) and metastasectomy are thought to have superior survival outcomes. We aimed to assess the patterns in surgical management of mCRC treatment over the last decade in the United States.

Methods/Interventions: The National Cancer Database (NCDB) was queried for patients diagnosed with mCRC. Patients with non-adenocarcinoma histology or missing survival information were excluded. We stratified patients according to treatment and plotted annual rates to assess trends over time. Statistical significance was assessed with the Cochran-Armitage test. For survival analysis, we used an Inverse Probability of Treatment Weighting (IPTW) to account for baseline differences between groups. Kapan-Meier curves and multivariable Cox proportional hazard models were used to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).

Results/Outcomes: 171,720 patients with mCRC were included in the analysis. Median age at diagnosis was 63 years and most patients were male (54%) and Caucasian (80%), with a Charlson Comorbidity Index of 0 (75%). 95% of patients were insured. Over the course of the study period (2010-2021) there was a decrease in PTR rate (53.1% to 40.5%; p< 0.001) as well as PTR combined with metastasectomy (19.4% to 16.6%; p< 0.001) and metastasectomy alone (17.6% to 13.8%; p< 0.001). Rates of systemic chemotherapy were unchanged (81.6 to 80.8%; p=0.1899), however, the proportion of patients receiving multi-agent chemotherapy increased (65.5 to 72.0%; p< 0.001) during the study period. Adjusted 5-year survival was highest in patients who received neoadjuvant chemotherapy followed by PTR and metastasectomy (41.1%; 95% CI 39.1-43.3%). Patients who received adjuvant chemotherapy after PTR and metastasectomy had a 5-year survival of 35.0% (95% CI 33.9-36.2%). Survival was lower in patients who underwent PTR with chemotherapy (25.2%; 95% CI 24.7-25.6%) but significantly better than chemotherapy only (8.8%; 95% CI 8.5-9.1%), and no treatment (5.7%; 95% CI 5.2-6.4%).

Conclusion/Discussion: In the last decade, the management of mCRC in the US has seen a significant de-escalation in PTR, concurrent with an intensification of systemic therapy towards multi-agent regimens. Despite these trends, multimodal treatment combining chemotherapy with surgery is associated with the best long-term survival. This survival benefit may advocate for more aggressive surgical management, however, there remains a significant potential for bias in patient selection in this retrospective analysis.

Temporal trends in the utilization of treatment strategies for patients with metastatic colorectal cancer in the National Cancer Database (NCDB), 2010-2021.
NCDB: National Cancer Database; PTR: Primary Tumor Resection
Kaplan-Meier estimates of overall survival for patients with metastatic colorectal cancer, stratified by main treatment strategy.
IPTW: Inverse Probability of Treatment Weighting; PTR: Primary Tumor Resection