Outcomes of neoadjuvant chemoradiotherapy followed by radical resection for T4 colorectal cancer

BACKGROUND Patients with clinical T4 colorectal cancer(CRC)have a poor prognosis because of compromised surgical margins.Neoadjuvant therapy may be effective in downstaging tumors,thereby rendering possible radical resection with clear margins.AIM To evaluate tumor downsizing and resection with clear margins in T4 CRC patients undergoing neoadjuvant concurrent chemoradiotherapy followed by surgery.METHODS This study retrospectively included 86 eligible patients with clinical T4 CRC who underwent neoadjuvant concurrent chemoradiotherapy followed by radical resection.Neoadjuvant therapy consisted of radiation therapy at a dose of 45-50.4 Gy and chemotherapy agents,either FOLFOX or capecitabine.A circumferential resection margin(CRM)of<1 mm was considered to be a positive margin.We defined pathological complete response(p CR)as the absence of any malignant cells in a specimen,including the primary tumor and lymph nodes.A multivariate logistic regression model was used to identify independent predictive factors for p CR.RESULTS For 86 patients who underwent neoadjuvant chemoradiotherapy and surgery,the rate of p CR was 14%,and the R0 resection rate was 91.9%.Of the 61 patients with rectal cancer,7(11.5%)achieved p CR and 5(8.2%)had positive CRMs.Of the 25 patients with colon cancer,5(20%)achieved p CR and 2(8%)had positive CRMs.We observed that the FOLFOX regimen was an independent predictor of p CR(P=0.046).After a median follow-up of 47 mo,the estimated 5-year overall survival(OS)and disease-free survival(DFS)rates were 70.8%and 61.4%,respectively.Multivariate analysis revealed that a tumor with a negative resection margin was associated with improved DFS(P=0.014)and OS(P=0.001).Patients who achieved p CR exhibited longer DFS(P=0.042)and OS(P=0.003)than those who did not.CONCLUSION Neoadjuvant concurrent chemoradiotherapy engenders favorable p CR and R0 resection rates among patients with T4 CRC.The R0 resection rate and p CR are independent prognostic factors for patients with T4 CRC.