Can lymph node ratio replace pn categories in the tumor-node-metastasis classification system for esophageal cancer?

We evaluated the prognostic value of lymph node ratio (LNR) in esophageal squamous cell carcinoma (ESCC) patients after tri-incisional esophagectomy by making comparisons with pN categories in the UICC/AJCC (International Union Against Cancer/American Joint Committee on Cancer) classification system (seventh edition).

Seven hundred ESCC patients underwent tri-incisional esophagectomy at our center (1988-2008) without neoadjuvant therapy. The adjusted X-tile cutoff values for LNR of 0 and 0.25 were compared with those in UICC/AJCC pN categories.

Univariate and multivariate analyses identified LNR as a significant prognostic factor regardless of the number of retrieved LNs. Spearman's correlation analysis showed close linear correlations between the number of examined and metastatic LNs (r = 0.205, p < 0.001), but not between the number of examined LNs and LNR (r = 0.058, p = 0.123). Significant prognostic differences were seen among LNR categories in all pT categories (p < 0.05), but not in pN categories stratified by tumor status (except T3: p < 0.001). Significant prognostic difference was seen among LNR categories in all pN categories (p < 0.05), but not between pN categories in all LNR categories (p > 0.05). Significant differences in 5-year cancer-specific survival rates were found among retrieved-node groups in the same pN category (except N2+3: p = 0.733), but not within the same LNR category (except N0: p < 0.001).

LNR is an independent prognostic factor after tri-incisional esophagectomy, regardless of the number of retrieved LNs. In ESCC, LNR might reduce stage migration, have more potential for predicting patient outcomes, and compensate for deficiencies in UICC/AJCC pN categories.