The prognostic value of lymph node ratio and log odds of positive lymph nodes in patients with lung adenocarcinoma

Objective: To investigate whether lymph node ratio and log odds ratio can be used for predicting the prognosis of patients with lung adenocarcinoma. Methods: A total of 1097 patients with lung adenocarcinoma who underwent complete surgical resection and systematic lymph node dissection between 2008 and 2013 were studied retrospectively. Lymph node ratio was calculated as: positive lymph nodes/total lymph nodes. Log odds ratio was calculated as: log positive lymph nodes+0.5/total lymph nodes-positive lymph nodes+0.5. Patients were grouped respectively into 4 groups by the use of recursive partitioning according to their lymph node ratio and log odds ratio. Linear trend chi(2) test was used for measuring monotonicity and discriminatory power. Results: The 3-year survival rate was 91.0%(89.9%-92.1%) for group 0, 75.2% (71.4%-79.0%) for group 1, 56.5% (51.5%-61.5%) for group 2, and 41.4% (36.4%-46.4%) for group 3 of lymph node ratio, respectively. In addition, the 3-year survival rate was 89.9% (88.7%-91.1%) for group 1, 78.4% (74.4%-82.4%) for group 2, 56.0% (50.9%-61.1%) for group 3, and 41.0% (36.1%-45.9%) for group 4 of log odds ratio, respectively. Univariable and multivariable Cox models identified that both lymph node ratio and log odds ratio were significant prognostic factors for patients' survival. Log-rank test of trend chi(2) statistics of both lymph node ratio (P< .001) and log odds ratio (P< .001) showed significant differences. Conclusions: Both lymph node ratio and log odds ratio can be used as prognostic factors for clinicians to predict patients' prognosis.