Increased breast cancer screening and downstaging in Colombian women: A randomized trial of opportunistic breast‐screening

The lack of breast cancer screening in low and middle‐income countries results in later stage diagnosis and worsened outcomes for women. A cluster randomized trial was performed in Bogotá, Colombia between 2008 and 2012 to evaluate effects of opportunistic breast cancer screening. Thirteen clinics were randomized to an intervention arm and 13 to a control arm. Physicians in intervention clinics were instructed to perform clinical breast examination on all women aged 50–69 years attending clinics for non‐breast health issues, and then refer them for mammographic screening. Physicians in control clinics were not explicitly instructed to perform breast screening or mammography referrals, but could do so if they thought it indicated (“usual care”). Women were followed for 2‐years postrandomization. 7,436 women were enrolled and 7,419 (99.8%) screened in intervention clinics, versus 8,419 enrolled and 1,108 (13.1%) screened in control clinics. Incidence ratios (IR) of early, advanced and all breast cancers were 2.9 (95% CI 1.1–9.2), 1.0 (0.3–3.5) and 1.9 (0.9–4.1) in the first (screening) year of the trial, and the cumulative IR for all breast cancers converged to 1.4 (0.7–2.8) by the end of follow‐up (Year 2). Eighteen (69.2%) of 26 women with early stage disease had breast conservation surgery (BCS) versus 6 (42.5%) of 14 women with late‐stage disease (p = 0.02). Fifteen (68.2%) of 22 women with breast cancer in the intervention group had BCS versus nine (50.0%) of 18 women in the control group (p = 0.34). Well‐designed opportunistic clinic‐based breast cancer screening programs may be useful for early breast cancer detection in LMICs.