Background: The risk of lymph node positivity (LN+) in rectal cancer is a parameter that impacts therapeutic recommendations. We aimed to quantify the effect of younger age on LN+ in rectal cancer.
Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database, patients with rectal cancer diagnosed between 1988 and 2008 were identified. Patients were stage I-III, without preoperative radiotherapy, at least one lymph node examined, and a standard rectal cancer operation performed. The association of age and LN+ status was examined with logistic regression separately for each T stage, adjusting for multiple covariates. Poisson regression was used to evaluate age and number of positive lymph nodes (LNs). All statistical tests were two-sided.
Results: Fifty-six thousand seventy-six patients were identified, including 1194 (2.1%) patients age 20 to 39 years at diagnosis and 4199 (7.5%) patients age 40 to 49 years (defined as young). For each T stage, LN+ was inversely associated with age (all P < .001). For T1, T2, and T3, age remained predictive of LN+ status after adjustment for number of LNs examined and other covariates (P < .001 for each stage). Adjusted odds ratios (ORs) for LN+ for age 20 to 39 vs 60 to 69 were: T1: 1.97(95% confidence interval [CI] = 1.36 to 2.86); T2: 1.48 (95% CI = 1.13 to 1.95); T3: 1.30 (95% CI = 1.10 to 1.53). Young age was a statistically significant predictor of an increased number of LNs positive for stage T2 (P = .042) and T3 (P = .002).
Conclusion: In this large national dataset, young age at diagnosis is associated with an increased risk of LN+. This finding merits further investigation and may ultimately impact treatment decision-making for young early-stage patients.