Does N ratio affect survival in D1 and D2 lymph node dissection for gastric cancer?

To identify whether there could have been changes in survival if lymph node ratio (N ratio) had been used.

We assessed 334 gastric adenocarcinoma cases retrospectively between 2001 and 2009. Two hundred and sixteen patients out of 334 were included in the study. Patients were grouped according to disection1 (D1) or dissection 2 (D2) dissection. We compared the estimated survival and actual survival determined by Pathologic nodes (pN) class and N ratio, and SPSS 15.0 software was used for statistical analysis.

Ninety-six (44.4%) patients underwent D1 dissection and 120 (55.6%) had D2 dissection. When groups were evaluated, 23 (24.0%) patients in D1 and 21 (17.5%) in D2 had stage migration (P = 0.001). When both D1 and D2 groups were evaluated for number of pathological lymph nodes, despite the fact that there was no difference in N ratio between D1 and D2 groups, a statistically significant difference was found between them with regard to pN1 and pN2 groups (P = 0.047, P = 0.044 respectively). In D1, pN0 had the longest survival while pN3 had the shortest. In D2, pN0 had the longest survival whereas pN3 had the shortest survival.

N ratio is an accurate staging system for defining prognosis and treatment plan, thus decreasing methodological errors in gastric cancer staging.