ePoster #2 | Clinical Science | Colorectal Surgery

A NATIONAL EVALUATION OF THE PREDICTORS OF COMPLIANCE AND SURVIVAL FROM ADJUVANT CHEMOTHERAPY IN HIGH-RISK STAGE II COLON CANCER: A NATIONAL CANCER DATABASE (NCDB) ANALYSIS
T Reif de Paula, E Haas, H Simon, M Profeta, P Gorroochurn, D Keller

Presenter: Thais Reif de Paula, MD, University of Houston

Background: US guidelines recommend adjuvant chemotherapy (AC) for stage II colon cancer with high-risk features to control distant disease and improve overall survival (OS). There is little study on compliance with guidelines or survival outcomes.

Objective: Our goal was to evaluate compliance rates with AC, factors associated with compliance, and OS in high-risk stage II colon cancer. Our hypothesis was that patients are not compliant with AC recommendations, but root causes can be identified and addressed to improve OS.

Method: The NCBD was reviewed for stage II colon cancer cases undergoing curative resection, with at least one high-risk feature(T4, <12 lymph nodes examined, positive margins, high-grade, perineural or lymph vascular invasion) from 2010-2015. We excluded patients receiving preoperative radiotherapy or chemotherapy, then stratified into AC and no AC cohorts. Multivariate logistic regression identified factors associated with AC compliance. Propensity score matching was performed to balance the cohorts and Kaplan-Meier analysis to assess OS. The main outcome measures were AC compliance, factors associated with compliance, and OS in high-risk stage II colon cancer.

Results: 33,878 patients were evaluated- 77.4% received no AC while 22.6% received AC. Factors associated with AC non-compliance were older age (OR .917; 95%CI .914-.921; p<.001), Medicare (OR .831; 95%CI .731-.968; p=.018) or Government (OR .754; 95%CI .653-.870; p=.018) payors, greater comorbidities (OR .439; CI95% .344-.559; p<.001), and the Midwest region (OR .872; 95%CI .786-.968; p=.010) Factors associated with compliance were pT4 stage (OR 3.878; 95%CI 3.587-4.194; p<.001), lymph vascular (OR1.347; 95%CI 1.249-1.453; p<.001) and perineural invasion (OR 1.153; 95%CI 1.050-1.266; p=.003), poor differentiation (OR 1.184; 95%CI 1.023-1.372; p=.024), compromised margins (OR 1.438; 95%CI 1.276-1.621; p<.001), and <12 lymph nodes retrieved (OR 1.250; 95%CI 1.131-1.379; p=<.001). In a matched cohort, AC significantly improved 1-, 3- and 5-year OS compared to no AC (96.2%, 85%, 75.2% and 87.9%, 74.1%, 62.8%; p<.001), with 5-year absolute risk reduction of 12.4%, relative risk reduction of 33.3 % and number needed to treat of 8.

Conclusion: Nationally, there is low compliance with AC in high-risk stage II colon cancer. Modifiable factors associated with low compliance were identified, highlighting opportunities to increase utilization. Despite the low compliance, AC was associated with improved OS. These results highlight the need for actions to improve AC compliance and outcomes in high-risk stage II colon cancer.

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