Prevalence and risk factors for lymph node metastasis after noncurative endoscopic resection for early gastric cancer: a systematic review and meta-analysis

BackgroundAdditional surgery for all patients with noncurative resection after endoscopic resection (ER) for early gastric cancer (EGC) may be excessive due to the relatively low rate of lymph node metastasis (LNM) in such patients. However, the prevalence and risk factors for LNM after noncurative ER have not been consistent across studies.MethodsWe performed a systematic review of electronic databases through August 10, 2018 to identify cohort studies with patients who underwent additional surgery after noncurative ER for EGC. The prevalence of LNM in such patients was extracted for all studies. Odds ratios (ORs) were combined using random-effects meta-analyses to assess the risk of LNM, when possible.ResultsWe identified 24 studies comprising 3877 patients with 311 having LNM (pooled prevalence, 8.1%). The risk of LNM was significantly increased in lymphatic invasion (OR [95% confidence interval] = 4.22 [2.88–6.19]), lymphovascular invasion (LVI) (4.17 [2.90–5.99]), vascular invasion (2.38 [1.65–3.44]), positive vertical margin (2.16 [1.59–2.93]), submucosal invasion depth of ≥ 500 μm (2.14 [1.48–3.09]), and tumor size > 30 mm (1.77 [1.31–2.40]). In contrast, there was no significant association between undifferentiated-type or ulceration (scar) and LNM. When studies were restricted to those that evaluated the adjusted OR, the risk of vascular invasion for LNM did not reach statistical significance.ConclusionsSeveral pathological factors, most notably lymphatic invasion and LVI, were associated with LNM in patients with noncurative resection after ER for EGC. Lymphatic and vascular invasion should be assessed separately instead of LVI (PROSPERO CRD42018109996).