Watanabe 2004 (JFMTC15‐2)

Methods	RCT (Randomised Controlled Trial); multicentre (Japan)
Participants	Patients with Dukes B and C (TNM stage II, III) rectal cancer undergoing radical surgery of the primary tumor (n=669)
Interventions	3‐arm trial: patients were randomly assigned to: either A) surgery alone (n=229), or B) surgery + adjuvant chemotherapy (n=218) with UFT (oral) + MMC and 5‐FU (intravenously), or C) surgery + adjuvant chemotherapy with UFT + MMC and 5‐FU combined with immunotherapy (OK‐432) (n=222)
Outcomes	Disease‐free survival (DFS) and overall survival (OS)
Notes	For this meta‐analysis, relevant data were retrieved from an individual patient data (IPD) meta‐analysis (Sakamoto 2007 (JFMTC15‐1)) where patients treated with surgery alone (n=122) were compared to patients undergoing surgery plus adjuvant treatment (n=269)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The registered cases were randomly assigned to the treatment groups according to the assignment table.
Allocation concealment (selection bias)	Low risk
Incomplete outcome data (attrition bias) All outcomes	High risk	Data were retrieved from an individual patients data (IPD) meta‐analysis (Sakamoto 2007 (JFMTC15‐1)) and were relative to 381 patients, whereas the original article was about 669 patients
Selective reporting (reporting bias)	Low risk
Other bias	Low risk