Background: Local resection of early-stage rectal cancer significantly reduces perioperative morbidity compared with radical resection. Identifying patients at risk of regional lymph node metastasis (LNM) is crucial for long-term survival after local resection.
Methods: Patients after oncological resection of T1 rectal cancer were identified in the Surveillance, Epidemiology, and End Results register 2004-2012. Potential predictors of LNM and its impact on cancer-specific survival were assessed in logistic and Cox regression with and without multivariable adjustment.
Results: In total, 1593 patients with radical resection of T1 rectal cancer and a minimum of 12 retrieved regional lymph nodes were identified. The overall LNM rate was 16.3 % (N = 260). A low risk of LNM was observed for small tumor size (P = 0.002), low tumor grade (P = 0.002) and higher age (P = 0.012) in multivariable analysis. The odds ratio for a tumor size exceeding 1.5 cm was 1.49 [95 % confidence interval (CI) 1.06-2.13], for G2 and G3/G4 carcinomas 1.69 (95 % CI 1.07-2.82) and 2.72 (95 % CI 1.50-5.03), and for 65- to 79-year-old and over 80-year-old patients 0.65 (95 % CI 0.43-0.96) and 0.39 (95 % CI 0.18-0.77), respectively. Five-year cancer-specific survival for patients with LNM was 90.0 % (95 % CI 85.3-95.0 %) and for patients without LNM 97.1 % (95 % CI 95.9-98.2 %, hazard ratio = 3.21, 95 % CI 1.82-5.69, P < 0.001).
Conclusions: In this population-based analysis, favorable cancer-specific survival rates were observed in nodal-negative and nodal-positive T1 rectal cancer patients after primary radical resection. The predictive value of tumor size, grading and age for LNM should be considered in medical decision making about local resection.
Keywords: Lymph node metastasis; Rectal cancer; Surveillance, Epidemiology, and End Results (SEER).