Background: Although there is evidence that failure to reach the baseline of 12–13 lymph nodes in resected specimens is related to poor prognosis of patients with stage II colon cancer, and may be a marker of adjuvant therapy, the use of these markers remains controversial. The objective of this study was to determine the advantage of chemotherapy treatment in patients with stage II colon cancer on the basis of the number of lymph nodes examined in radical surgery.
Patients and methods: Using monitoring, epidemiology, and final outcome Medicare database, we authenticated 9,651 patients aged ≥66 years diagnosed with resected stage II colon cancer from 1999 to 2004. Medical insurance claims determined the adoption of chemotherapy within 3 months after radical operation. The relation between patient/tumor characteristics (including the number of lymph nodes examined) and the use of adjuvant chemotherapy was tested using chi-squared test and multiple logistic regression. Multivariate Cox model was used to compare survival rates between the treatment and untreated groups.
Results: Most patients (54.8%) had only 1–12 lymph nodes examined, while only 41.6% of the patients had >12 lymph nodes examined. Overall, 20.9% of patients received adjuvant chemotherapy; there was no relationship between chemotherapy and the number of lymph nodes examined (P =0.984). The presence of 12 or fewer lymph nodes in surgical specimens was related to poor overall survival (OS; adjusted hazard ratio [HR] 1.31, 95% CI 1.21–1.41). Although adjuvant chemotherapy was related to our cohort improvement, its beneficial effects on OS (HR: 0.73; 95% CI: 0.64–0.83) and disease-free survival (HR: 0.71; 95% CI: 0.60–0.85) only existed in patients with 0–12 lymph nodes examined.
Conclusion: The presence of 12 or fewer lymph nodes in surgical specimens is related to poor prognosis and survival benefit in adjuvant chemotherapy for stage II colon cancer patients. More attention should be paid to the implementation of recommendations for lymph node dissection to help identify patients who really benefit from adjuvant chemotherapy after colectomy.
Keywords: colon cancer, chemotherapy, prognosis