Sasako 2008.

Methods	Method of randomization: "the surgeon contacted the [data center] by telephone to receive a randomly generated assignment" Exclusion after randomization: none Lost to follow‐up: none Method of allocation concealment: "the surgeon contacted the [data center] by telephone to receive a randomly generated assignment" Intention‐to‐treat analysis: yes Description of sample size calculation: reported (expected number: 412)
Participants	Number randomly assigned: 523 (D3 = 260, D2 = 263) Age (mean): 60 years Sex (M/F): 359/164 Inclusion criteria: patients with resectable primary non‐metastatic gastric carcinoma Equivalence of baseline characteristics: age, sex and stage distribution similar for both groups
Interventions	D3 versus D2 lymphadenectomy (during gastrectomy)
Outcomes	Overall survival (D3 vs D2): HR 1.03, 95% CI 0.77 to 1.37 Disease free survival (D3 vs D2): HR 1.08, 95% CI 0.83 to 1.42 Postoperative deaths: 2 (D3), 2 (D2)
Notes	Country: Japan Median follow‐up: 5.7 years
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk
Allocation concealment (selection bias)	Low risk
Blinding of participants and personnel (performance bias) All outcomes	Low risk
Blinding of outcome assessment (detection bias) All outcomes	Low risk
Incomplete outcome data (attrition bias) All outcomes	Low risk
Selective reporting (reporting bias)	Low risk
Other bias	Low risk