Neoadjuvant Radiation Therapy in Locally Advanced Colon Cancer: a Cohort Analysis

Background: A paucity of data exists in the use of neoadjuvant chemoradiation therapy (NRT) for T4, non-metastatic colon cancer. This study was conducted to determine the effect of NRT on outcomes after resection for T4 colon cancer. Methods: All patients with non-metastatic resected clinical T4 colon cancer from 2000 to 2012 at a tertiary care center were included. The cohort was divided into two groups—those that received NRT and those that did not (non-NRT). The primary outcomes were margin-negative resection and overall survival (OS). Results: One hundred and thirty-one consecutive patients with non-metastatic clinical T4 colon cancer with a mean age of 65 years were included. NRT was used in 23 patients (17.4%). NRT group was noted to have non-statistically significant improvement in R0 resection rate (NRT 95.7% vs non-NRT 88.0%; p = 0.27) and local recurrence (NRT 4.3% vs non-NRT 15.7%; p = 0.15). There was a significant difference in T-stage downstaging between the two groups (NRT 30.4% vs non-NRT 6.5%; p = 0.007). In a bivariate analysis, NRT was associated with improved 5-year OS (NRT 76.4% vs non-NRT 51.5%; p = 0.03). This relationship did not persist in a Cox proportional hazard analysis that included age and comorbidity (HR 2.19; 95% CI 0.87–5.52; p = 0.09). Conclusions: The use of NRT in locally advanced T4 colon cancer is safe and associated with increased downstaging. While there was a trend toward improvement in local recurrence and the ability to obtain margin-negative resections in the NRT group, this was not significant. Significantly improved overall survival was not observed in a multivariable analysis.