Determination of the extent of dissection in early gastric cancer based on lymph node station power index

Abstract

Abstract Background The relative prognostic value of each lymph node (LN) station remains undefined in the treatment of gastric cancer. This study aimed to develop a new method to evaluate LN station ranking and define the optimal extent of lymphadenectomy for early gastric cancer. Methods Clinical and histopathological information from patients who underwent curative gastrectomy with lymphadenectomy between 1989 and 2018 was reviewed. The LN station power index (LNPI) of each station was estimated using a LN retrieval frequency and the 5-year overall survival of patients with absence of LN at each station. External validation was conducted to evaluate the relevance of the LNPI. Results A training set was developed from examination of 7009 patient records. For most nodal stations, the absence of LN was significantly associated with a poor prognosis. For the perigastric stations, the prognostic value assessed using the LNPI was in the following order: LN 4 (LNPI = 19.68), LN 3 (LNPI = 17.58), LN 6 (LNPI = 15.16), LN 1 (LNPI = 6.71), LN 2 (LNPI = 4.64) and LN 5 (LNPI = 2.86). The value rank of the extra-gastric stations was in the following order: LN 8a (LNPI = 12.93), LN 7 (LNPI = 10.51) and LN 9 (LNPI = 9.70), but the index of LN 12a (LNPI = 4.79) was higher than that of LN 11 (LNPI = 4.78). These trends in the LNPI were similar in the validation patient cohort. Conclusions The LNPI is a simple tool to rank the priority of each LN station dissection. The optimal extent of D1 + lymphadenectomy using LNPI was determined to be D1 with LNs 7, 8a and 9.