Prognostic Significance of the Lymph Node Ratio Regarding Recurrence and Survival in Rectal Cancer Patients Treated with Postoperative Chemoradiotherapy

BACKGROUND/AIMS: To evaluate the prognostic impact of the lymph node ratio (LNR: the ratio of positive lymph nodes to the total number of lymph nodes examined) on disease recurrence and survival among rectal cancer patients who received curative surgery and postoperative chemoradiotherapy (CRT). METHODS: Between 1995 and 2008, 124 patients with pathologic T3-4 or node-positive rectal cancer underwent curative surgery and postoperative CRT. Postoperative radiotherapy was delivered at a median dose of 50.4 Gy (range, 45 to 59.4 Gy) for 6 weeks. Chemotherapy consisted of a bolus injection of 5-fluorouracil and leucovorin in the first and last week of radiotherapy (91.9%) or daily capecitabine during radiotherapy (8.1%). Further adjuvant chemotherapy was administered after chemoradiation. RESULTS: The median follow-up was 5.1 years. In the multivariate analysis, pathologic N (pN) stage and lymphovascular invasion were significantly associated with disease-free survival and disease-specific survival (p<0.05). However, when the LNR with a cutoff value of 0.2 was included as a covariate in the model, the LNR was highly significant (p<0.001), and the pN stage lost its significance (p>0.05). CONCLUSIONS: The LNR predicts recurrence and survival more accurately than pN stage. The pN stage and the LNR should be considered together when estimating the risk of disease recurrence among rectal cancer patients.