Nationwide study of the impact of D2 lymphadenectomy on survival after gastric cancer surgery

BACKGROUND: Gastrectomy including D2 lymphadenectomy is regarded as the standard curative treatment for advanced gastric cancer in Asia. This procedure has also been adopted gradually in the West, despite lack of support from RCTs. This study sought to investigate any advantage for long-term survival following D2 lymphadenectomy in routine gastric cancer surgery in a Western nationwide population-based cohort. METHODS: All patients who had a gastrectomy for cancer in Sweden in 2006-2017 were included in the study. Prospectively determined data items were retrieved from the National Register of Oesophageal and Gastric Cancer. Extent of lymphadenectomy was categorized as D1+/D2 or the less extensive D0/D1 according to the Japanese Gastric Cancer Association classification. Overall survival was analysed and, in addition, a variety of possible confounders were introduced into the Cox proportional hazards regression model. RESULTS: A total of 1677 patients underwent gastrectomy, of whom 471 (28·1 per cent) were classified as having a D1+/D2 and 1206 (71·9 per cent) a D0/D1 procedure. D1+/D2 lymphadenectomy was not associated with higher 30- or 90-day postoperative mortality. Median overall survival for D1+/D2 lymphadenectomy was 41·5 months with a 5-year survival rate of 43·7 per cent, compared with 38·5 months and 38·5 per cent respectively for D0/D1 (P = 0·116). After adjustment for confounders, in multivariable analysis survival was significantly higher after D1+/D2 than following D0/D1 lymphadenectomy (hazard ratio 0·81, 95 per cent c.i. 0·68 to 0·95; P = 0·012). CONCLUSION: This national registry study showed that long-term survival after gastric cancer surgery was improved after gastrectomy involving D1+/D2 lymphadenectomy compared with D0/D1 dissection.