Screening and Validation of a Novel T Stage-Lymph Node Ratio Classification for Colon Cancer

Purpose Lymph node ratio (LNR) has advantages in predicting prognosis over the American Joint Committee on Cancer (AJCC) N stage. However, the prognostic value of establishing a novel T stage-Lymph Node Ratio classification (TLNR) for colon cancer by combining LNR and T stage is currently unknown.Methods We included 62,294 stage I-III colon cancer patients from the SEER data base as a training cohort. An external validation was performed in 3,327 additional patients. A novel LNR stage was established and included into a novel TLNR classification by combining with T stage. Patients with similar survivals were grouped according to T and LNR stages, with T1LNR1 as a reference. Results We developed a novel TLNR classification: stages I (T1LNR1-2, T1LNR4), IIA (T1LNR3, T2LNR1-2, T3LNR1), IIB (T1LNR5, T2LNR3-4, T3LNR2, T4aLNR1), IIC (T2LNR5, T3LNR3-4, T4aLNR2, T4bLNR1), IIIA (T3LNR5, T4aLNR3-4, T4bLNR2), IIIB (T4aLNR5, T4bLNR3-4), and IIIC (T4bLNR5). In the training cohort, the TLNR had better prognostic discrimination [area under receiver operating characteristic curve (AUC), 0.621 vs. 0.608, P < 0.001], superior model-fitting ability in predicting overall survival [Akaike information criteria (AIC), 561,129 vs. 562,052], and better net benefits than the AJCC 8th tumor/node/metastasis (TNM) classification. Those results were successfully validated in predicting both overall and disease-free survivals in an independent validation set. Conclusions The TLNR classification has better prognostic discrimination, model-fitting ability and net benefits than the AJCC 8th TNM classification for better stratifying operable colon cancer patients, especially in patients with less than 12 retrieved lymph nodes.