Background: JCOG0912 supports the non-inferiority of laparoscopy-assisted distal gastrectomy (LADG) compared with open distal gastrectomy (ODG) for clinical stage I gastric cancer relapse-free survival (RFS), suggesting that LADG should be considered a standard treatment option when performed by experienced surgeons. No prospective study evaluating laparoscopy-assisted total gastrectomy (LATG) and laparoscopy-assisted proximal gastrectomy (LAPG) has been completed in terms of both safety and long-term survival. Considering that the results of the phase III trial to evaluate the long-term outcome of LADG (JCOG0912) could guarantee that of LATG/LAPG, we conducted a single-arm confirmatory trial (JCOG1401) to evaluate the safety of LATG/LAPG for clinical stage I proximal gastric cancer and JCOG1401 confirmed the safety of LATG/LAPG. Long-term outcomes as the secondary endpoints of this study are reported here after 5-year follow-up period. Methods: Laparoscopic operators were limited to credentialed surgeons. The extent of nodal dissection was selected based on the Gastric Cancer Treatment Guidelines in Japan. The primary endpoint was the proportion of grade 2 (CTCAE ver. 4.0) or greater esophageal anastomotic leak. The sample size was determined to be 245 considering a threshold of 8% and expected value of 3% with a one-sided alpha error of 2.5% and statistical power of 90%. The secondary endpoints were overall survival (OS) and RFS. Results: Between April 2015 and February 2017, 245 patients were enrolled. Among them, 1 patient was excluded from safety analysis due to ineligible. LATG/LAPG was performed in 195/49. 170/47/17/8/2 patients had pStage IA/IB/II/IIIA/IIIB disease and 190/31/15/8 patients had pT1/T2/T3/T4 disease, respectively. Grade 2 or greater esophageal anastomotic leak was 2.5% (6/244) (95% CI 0.9-5.3), as previously reported. 5-year OS was 91.2% (95% CI 86.9-94.2). 5-year RFS was 90.0% (95% CI 85.5-93.2). Among 22 deaths, 14 patients died without recurrence and 8 patients died with recurrence. Twelve recurrences were observed in 5/2/4/1 patients for pT1/T2/T3/T4. The sites of recurrence were peritoneal metastasis in 2 cases, hematogenous metastasis in 9 cases (liver: 6, bone: 2, lung: 1), and other in 1 case. Conclusions: The long-term outcomes of LATG/LAPG for Stage I gastric cancer patients were excellent and seem comparable to those of open procedures. Similar to JCOG0912, JCOG1401 guarantee the long-term survival of LATG/LAPG. Clinical trial information: UMIN000017155.