IBCSG‐10‐93.

Methods	Study design: RCT (originally conceived as a non‐inferiority trial – see notes Country: international Study period: 1993‐2002 Inclusion criteria: postmenopausal patients aged ≥ 60 years with clinically node‐negative operable breast cancer.  All patients had a histologically proven unilateral breast cancer of stage T1a‐b, T2a‐b, T3, N0 or M0 with ER‐positive or ER‐negative primary tumours. Exclusion criteria: treatment started before randomisation, prior or concurrent malignancy Length of follow up: median = 6.6 years
Participants	No. in trial arms: surgery alone: N = 239; ALND: N = 234 Age: surgery alone: median (range) = 74 (60‐91) years; ALND: median (range) = 74 (60‐91) years Stage distribution: not reported, but tumour size was as follows: surgery alone: ≤ 20 mm, N = 137; > 20 mm, N = 100; unknown, N = 2. ALND: ≤ 20 mm, N = 126; > 20 mm, N = 100; unknown, N = 8 Proportion node positive: surgery alone: not examined (axilla not dissected in N = 232/239); ALND: N = 64/230 (axilla not dissected in N = 4) Pathological type of breast cancer: not reported, but ER status was as follows: surgery alone: positive, N = 201; negative, N = 31; unknown, N = 7. ALND: positive, N = 179; negative, N = 46; unknown, N = 9
Interventions	Surgery alone (total mastectomy, N = 106; breast‐conserving surgery with (N = 77) or without (N = 56) radiotherapy) vs surgery (total mastectomy, N = 105; breast‐conserving surgery with (N = 78) or without (N = 51) radiotherapy) + axillary clearance
Outcomes	Quality of life (including adverse events), disease‐free survival, overall survival
Axillary node surgery	Minimum no. nodes to be removed according to protocol: not reported Nodes removed clearance arm: not reported Nodes removed no axillary surgery: not reported Method of node pathological analysis: not reported Further treatment for node‐positive cases: no
Radiotherapy	Both arms: Radiotherapy using 2 tangential fields was recommended after breast‐conserving surgery. No further details were reported. RT same in all trial arms? not reported
Hormone and chemotherapy	HRT: surgery alone: no, N = 184; yes, N = 52; unknown, N = 3. ALND: no, N = 184; yes, N = 50 Both arms: Participants were treated with adjuvant tamoxifen (20 mg) for 5 years. In August 2002, IBCSG Scientific Commmittee made a recommendation to discontinue tamoxifen for participants with endocrine non‐responsive tumours.
Notes	N = 19 did not meet protocol eligibility criteria, but these patients were included in intention‐to‐treat analyses. Originally designed as a non‐inferiority trial with estimated sample size of 1020 – poor accrual meant a change in design to assess whether avoiding ALND improved quality of life Baseline differences? Paper states that baseline characteristics were balanced according to randomly assigned treatment arms Intention‐to‐treat analyses? Survival, disease control in the axilla, breast cancer recurrence: Paper states that intention‐to‐treat analysis was employed. Short‐term and long‐term adverse events: data not available for all participants
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Permuted blocks randomisation schedule was produced by use of pseudo‐random numbers generated by a congruence method.
Allocation concealment (selection bias)	Low risk	Random assignment was performed centrally.
Blinding of outcome assessment (detection bias) Disease control in the axilla	Unclear risk	No details were provided.
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	No details were provided.
Blinding of outcome assessment (detection bias) Long term adverse events	Unclear risk	No details were provided.
Incomplete outcome data (attrition bias) Survival	Low risk	Data appear to be available for all participants.
Incomplete outcome data (attrition bias) Axillary recurrence	Low risk	Data appear to be available for all participants.
Incomplete outcome data (attrition bias) Breast cancer recurrence	Low risk	Data appear to be available for all participants.
Incomplete outcome data (attrition bias) Short term adverse events	High risk	Data were available only for subgroups of surgery alone participants and ALND participants.
Incomplete outcome data (attrition bias) Long term adverse events	High risk	Data were available only for subgroups of surgery alone participants and ALND participants.
Selective reporting (reporting bias)	Unclear risk	Some adverse events were not reported.