Mittra 2021.

Study characteristics
Methods	Design: RCT Unit: 20 clusters (slums)
Participants	Location/setting: study was carried out in Mumbai, India. Health workers who had passed 10th grade education were trained to conduct CBE within 4 weeks to perform on participants in the study. Sample size: 151,538 women aged 35 to 64 Sex: only females were included. Mean age: mean age for enrolment for all trial participants in the screening and control arm was 44.84 and 44.92 years respectively. Inclusion criteria: women aged 35 to 64 years who did not have a history of breast cancer. Exclusion criteria: women outside of ages 35 to 64 years, and all women with a history of breast cancer.
Interventions	Intervention (screening) group: (n = 75,360) of 10 clusters must undergo 9 rounds of biennial monitoring for breast cancer occurrence and mortality, 4 rounds of screening by CBE and cancer awareness education and 5 rounds of active surveillance. Control group: (n = 76,178) of 10 clusters must undergo 9 rounds of biennial monitoring for breast cancer occurrence and mortality, 1 round cancer awareness education, 8 rounds of active surveillance. Trial duration was 20 years.
Outcomes	Primary outcomes: the down‐staging of breast cancer at diagnosis and reduction in mortality from breast cancer. Secondary outcomes: CBE coverage, sensitivity, and specificity. Timing of outcome assessments: total trial duration was 20 years, but database was locked in March 2019 for analysis.
Notes	Study start date: May 1998 Study end date: March 2019 Funding source: US National Institutes of Health (grant number: RO1CA074801) Conflicts of interest: author conflicts not declared
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "These 20 clusters were then randomly assigned to the screening and control (health education) arms." Comment: insufficient information pertaining to the method of sequence generation to permit judgement.
Allocation concealment (selection bias)	Unclear risk	Comment: insufficient information to permit judgement.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Comment: probably not done. Each participant and health worker were aware of the arm to which the participant were allocated.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Comment: probably not done. Each participant and health worker were aware of the arm to which the participant were allocated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Comment: out of 75,360 eligible women listed in the screening arm 69,227 (90.88%), 62,755 (86.98%) and 59,543 (88.00%) women participated in the first, second, and third screening rounds for breast cancer.
Selective reporting (reporting bias)	High risk	Comment: these were interim analysis results as the trial is ongoing and cost‐effectiveness of CBE has not been reported
Other bias	Low risk	Comment: no other biases detected.