Recurrence Outcomes Less Favorable in T1 Rectal Cancer than in T1 Colon Cancer

BACKGROUND With the implementation of screening program worldwide, diagnosis of early-stage colorectal cancer steadily increased, including T1 cancer. Current T1 cancer treatment does not differ according to anatomic location. We therefore compared the disease-free survival of T1 cancer arising from rectum versus colon. METHODS The hospital-based study included subjects with T1 cancer at National Taiwan University Hospital from 2005 to 2014. Clinical, colonoscopy, and histopathology were reviewed for patients with a mean follow-up time of 7.1 (0.7-12.9) years. We conducted Kaplan-Meier analysis to compare the risk of recurrence by cancer location and Cox-regression analysis to identify risk factors for T1 cancer recurrence. RESULTS The final cohort included a total of 343 subjects with T1 cancer (mean age, 64.9 ± 11.7 years; 56.1% males), of whom 25 underwent endoscopic resection alone. Of the subjects who underwent surgery, 50 had lymph node metastasis and 268 did not. Kaplan-Meier analysis showed that the risk of recurrence was higher in T1 rectal cancer than T1 colon cancer (p =0.022). Rectal location, and larger neoplasm size were independent risk factors for recurrence, with hazard ratios (95% confidence interval) of 4.84 (1.18-19.92), and 1.32 (1.06-1.65), respectively. The occurrence of advanced histology did not differ between T1 rectal and colon cancers (p = 0.58). CONCLUSION T1 cancers arising from the rectum had less favorable recurrence outcomes than those arising from the colon. Further studies are needed to examine whether adjuvant radiotherapy or chemotherapy can reduce the risk of recurrence in T1 rectal cancer. IMPLICATIONS FOR PRACTICE Current T1 colorectal cancer treatment and surveillance do not differ according to anatomic location. Clinical, colonoscopy, and histopathology were reviewed for 343 T1 cancer patients with a mean follow-up time of 7.1 years. Kaplan-Meier analysis showed that the risk of recurrence was higher in T1 rectal cancer than T1 colon cancer. Moreover, the rectal location was an independent risk factor for recurrence. T1 cancers from the rectum had less favorable recurrence outcomes than those arising from the colon. It is critical to clarify whether adjuvant therapy or more close surveillance can reduce recurrence risk in T1 rectal cancer.