Recurrence pattern and outcomes in T4 colon cancer: A single institution analysis.

Abstract

706 Background: Patients with T4 colon adenocarcinoma have an increased risk of peritoneal recurrence due to direct seeding malignant cells. It has been theorized that adjuvant chemotherapy may not sterilize the peritoneal surface due to inadequate intraperitoneal concentration. We seek to further define the metastatic pattern, predictors of recurrence, and efficacy of adjuvant treatment in T4 colon cancer. Methods: We reviewed records of 181 adults [median age 71 (22-97)] with T4 N0-3 colon adenocarcinoma at Beaumont Hospital, Michigan from May 2005 –Nov 2015. Baseline factors and data on follow up, metastasis, and survival were collected and analyzed. Results: Overall recurrence rates for N0, N1, and N2 were 27/85 (32%), 17/50 (34%), and 29/46 (63%) (p = 0.001). Locoregional recurrence (LR) rates for N0, N1, and N2 were 21/85 (24.7%), 14/50 (28%), and 21/46 (45.7%) (p = 0.014). Multivariate analysis for distant recurrence was significant only for positive nodes with hazard ratio (HR) 3.3, 95% confidence interval (CI) 1.1-9.9. Multivariate analysis for increased risk of LR was significant for the following variables: perforation (HR 2.7, 95% CI 1.2 – 6.2), lymphovascular invasion (HR 2.7, 95% CI 1.1 – 6.7), positive nodes (HR 2.8, 95% CI 1.2 – 6.9), and positive margins (HR 5.0, 95% CI 2.1 – 12.1). Adjuvant chemotherapy did not decrease risk of LR (HR 0.6, 95% CI 0.3-1.2) or distant recurrence (HR 0.9, 95% CI 0.3-2.8). Multivariate analysis for overall survival revealed the following to be associated with increased risk of mortality: signet ring (HR 2.5, 95% CI 1.2-5.8), positive nodes (HR 2.3, 95% CI 1.2-4.4), positive margin (HR 2.8, 95% CI 1.4-5.8). Adjuvant chemotherapy was not associated with improved survival (HR 0.8, 95% CI 0.4-1.7). Recurrence was strongly associated with colon cancer-specific death with a p < 0.001. Conclusions: Adjuvant chemotherapy is standard of care for most T4 colon cancer patients, however, this data suggests there is no improvement in survival or other significant outcomes. We have identified several risk factors which predict increased risk of LR. This data suggests LR is frequent and not affected by systemic chemotherapy. Prospective trials are needed to reduce the substantial risk of LR in T4 colon cancer.