Hammersmith.

Methods	Study design: RCT Country: UK Study period: 1965‐1970 Inclusion criteria: patients with clinical stage T1N0, T2N0, T1N1 and T2N1 primary lesions and no evidence of distant metastatic disease; patients with T3 lesions for which the T3 category was decided solely on the size of the tumour; and patients with clinically involved axillary nodes were included, irrespective of the size and position of nodes, but only if they remained mobile.   Exclusion criteria: patients with lesions that had excessive skin tethering or any attachment to pectoral muscles, patients with fixed axillary nodes (N2) or involved supraclavicular nodes (N3)  Length of follow up: 4‐9 years (median not reported. If recruitment was at a constant rate, median follow‐up would be 6.5 years by 1974)
Participants	No. in trial arms: radical: N = 95; simple: N = 100 Age: not reported Stage distribution: not reported Proportion node positive: not reported by trial arm (overall 79/195 – 41% had clinically involved nodes at time of trial entry) Pathological type of breast cancer: not reported
Interventions	Simple total mastectomy + postoperative radiotherapy vs radical mastectomy (Halsted) + postoperative radiotherapy
Outcomes	Overall survival, short‐term postoperative mortality, local recurrence, morbidity (stiff shoulder, swollen arm)
Axillary node surgery	Minimum no. nodes to be removed according to protocol: not reported Nodes removed clearance arm: not reported Nodes removed SNLB: not reported Method of node pathological analysis: not reported Further treatment for node‐positive cases: no
Radiotherapy	Radical: postoperative radiotherapy to the apex of the axilla and to supraclavicular, infraclavicular and internal mammary lymph nodes Simple: postoperative radiotherapy to the chest wall, axilla and supraclavicular, infraclavicular and internal mammary lymph nodes RT same in all trial arms? no
Hormone and chemotherapy	All but 1 participant who were premenopausal or within 10 years of stopping menstruation also received ‘prophylactic’ oophorectomy, which usually was carried out at the time of mastectomy.
Notes	100% follow up (1974), although some follow‐up was conducted by post. Need to locate final trial report if it was ever published Baseline differences? For allocation of participants, paired stratification was employed with the following stratification factors: age, menopausal status, child‐bearing history and exact clinical stage (TNM). No further details were reported. Intention‐to‐treat analyses? Data were reported only for 76 matched participant pairs. 22% of participants were excluded from analysis because they were unmatched. Were these unmatched participants different in a systematic way?
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were randomly allocated to 1 or another of the 2 treatment groups after matching, via random number tables.
Allocation concealment (selection bias)	Unclear risk	For allocation of participants, paired stratification was employed with the following stratification factors: age, menopausal status, child‐bearing history and exact clinical stage (TNM). No further details were reported.
Blinding of outcome assessment (detection bias) Disease control in the axilla	Unclear risk	Outcome was not reported.
Blinding of outcome assessment (detection bias) Breast cancer recurrence	Unclear risk	No details were provided.
Blinding of outcome assessment (detection bias) Short term adverse events	Unclear risk	Outcome was not reported.
Blinding of outcome assessment (detection bias) Long term adverse events	Unclear risk	No details were provided.
Incomplete outcome data (attrition bias) Survival	Unclear risk	Data were reported only for the 76 matched participant pairs. 22% of participants were excluded from analysis because they were unmatched. Were these unmatched participants different in a systematic way?
Incomplete outcome data (attrition bias) Axillary recurrence	Unclear risk	Outcome was not reported.
Incomplete outcome data (attrition bias) Breast cancer recurrence	Unclear risk	Data were reported only for the 76 matched participant pairs. 22% of participants were excluded from analysis because they were unmatched. Were these unmatched participants different in a systematic way?
Incomplete outcome data (attrition bias) Short term adverse events	Unclear risk	Outcome was not reported.
Incomplete outcome data (attrition bias) Long term adverse events	Low risk	All 195 participants were measured for stiff shoulder/swollen arm.  Follow‐up was reported as 100%.
Selective reporting (reporting bias)	Unclear risk	Short‐term adverse events were not reported.