A. T. Hawkins1, T. M. Geiger1, M. Ford1, R. L. Muldoon1, B. Hopkins1, L. A. Kachnic1, S. Glasgow2 1Vanderbilt University Medical Center,Nashville, TN, USA 2Washington University,Colon And Rectal Surgery,St. Louis, MO, USA
Introduction: Compared with lower tumor stages, resection of locally advanced colon cancer (LACC) is associated with poor survival. Few strategies are available to address this disparity. Data on the effect of neoadjuvant radiation therapy (NRT) to improve resectability and survival is lacking. We hypothesized that NRT will result in increased R0 resection, decreased multivisceral resection rates and improved overall survival in patients with LACC.
Methods: The National Cancer Database (NCDB 2004-2014) was queried for adults with clinical evidence of LACC (defined as clinically evident T4 disease prior to surgery) who underwent curative resection. Patients with metastatic disease or in whom clinical staging data was unavailable were excluded. Patients were divided into two groups – those who underwent NRT and those that did not. Bivariate and multivariable analyses were used to examine the association between NRT and R0 resection rate, multivisceral resection and overall survival.
Results: 15,207 patients with clinical T4 disease who underwent resection were identified over the study period. 195 (1.3%) underwent NRT. The majority of patients in the NRT group underwent 4500 cGy of radiation in 25 fractions over five weeks (range: 3900- 5040 cGy). Rate of NRT utilization did not change by year. Factors associated with the use of NRT included younger age, male gender, private insurance, lower Charlson comorbidity score, and treatment at an academic/research program. NRT was associated with superior R0 resection rates (NRT 87.2% vs. No NRT 79.8%; p=0.009) but not lower multivisceral resection rates (NRT 45.6% vs. No NRT 21.5%; p< 0.001). Five-year overall survival was increased in the NRT group (NRT 62.0% vs. No NRT 45.7%; p< 0.001; PLEASE SEE FIGURE). The benefit of NRT persisted in a Cox proportional hazard multivariable model containing a number of confounding variables including comorbidity, multivisceral resection and postoperative chemotherapy (OR 1.30; 95%CI 1.01-1.69; p=0.04).
Conclusion: Younger age, male gender, private insurance, lower Charlson comorbidity score, and treatment at an academic/research program were associated with increased rates of NRT utilization. Although radiation is rarely used in locally advanced colon cancer, this NCDB analysis suggests that the use of neoadjuvant radiation for clinical T4 disease may be associated with superior R0 resection rates and improved overall survival. NRT should be considered on a case-by-case basis in locally advanced colon cancer. Further research is necessary to identify patients that will benefit the most from this approach.
