Abstract Background Despite the increasing incidence of early onset T1 colorectal cancer (T1 CRC), its features remain poorly understood. We examined whether early onset T1 CRC is associated with a higher rate of lymph-node metastasis (LNM). Methods We included studies reporting age-specific LNM rates for patients aged < 50 and ≥ 50 years. Sensitivity analyses were performed to assess the impact of overlapping and selected subset datasets. Subgroup analyses were conducted to evaluate the association between clinicopathological variables and age. The risk of bias was assessed using the Risk of Bias In Non-randomized Studies of Interventions Version 2. Results Of the 1214 records identified, 10 studies comprising 11 databases were included. After excluding overlapping and selected subset data, six databases from five studies with 29,132 patients were analyzed. Of these, 2759 (9.4%) were aged < 50 years at diagnosis, and the pooled LNM rates were 19.2% (95% confidence interval CI, 17.8–20.6) in early onset and 11.1% (95% CI 10.7–11.5) in late-onset T1 CRC, representing an absolute difference of approximately 8%. Early onset T1 CRC was associated with higher odds of LNM than late-onset disease (OR: 1.94; 95% CI 1.75–2.15; I 2 = 0%). Despite serious confounding in three studies, multivariable analyses adjusting for clinical covariates showed that younger age was associated with higher odds of LNM, and adjusted ORs for older patients ranged between 0.46 and 0.90 compared with those aged < 50 years. Conclusions This meta-analysis demonstrated that early onset T1 CRC is associated with higher odds of LNM compared with late-onset T1 CRC in surgically treated patients.
Fukuda et al. (Mon,) studied this question.