Age and Lymph Node Positivity in Patients With Colon and Rectal Cancer in the US Military Health System

Background: Young age may be associated with an increased risk of lymph node involvement at diagnosis of colorectal cancer. Accessibility to care, which is related to cancer detection, tumor stage, and therefore lymph node positivity, may vary by age and thus influence research results. Objective: The purpose of this study was to investigate whether young patients had an increased risk of lymph node-positive colon and rectal cancers in the Department of Defense Military Health System, which provides universal health care to its beneficiaries. Design: This was a retrospective, cross-sectional study. SETTINGS: Patients were identified from the US Department of Defense Automated Central Tumor Registry. Patients: Included patients were diagnosed with histologically confirmed primary stage I to III colon and rectal adenocarcinomas between 1989 and 2013, had surgery and ≥1 lymph node examined, and did not receive preoperative radiotherapy. Logistic regression was used to examine the relationships between age at diagnosis (18-49, 50-59, 60-69, and ≥70 y) and lymph node positivity overall and stratified by tumor T stage and number of lymph nodes examined. Main Outcome Measures: Lymph node positivity of colon and rectal cancers was measured. Results: The youngest patients (aged 18-49 y) were more likely to have lymph node-positive colon and rectal cancers compared with those who were aged ≥70 years after adjustment for potential confounders (OR = 2.04 and 95% CI, 1.63-2.56 for colon cancer; OR = 1.73 and 95% CI, 1.11-2.70 for rectal cancer). A similar tendency was shown in most colon and rectal cancer subgroups stratified by tumor T stage and number of lymph nodes examined. Limitations: This study was limited by its small sample size for certain subgroup analyses. No information on comorbidities, BMI, or other indicators of health status was available. Conclusions: In a universal healthcare system, young age was associated with increased lymph node positivity of colon and rectal cancers, suggesting that factors other than access to care may play a role in this association.