BACKGROUND AND PURPOSE:

• In low- and middle-income countries, breast cancer is often detected at advanced stages
• Clinical breast examination (CBE) may be a good screening method in this setting
• Mittra et al. (BMJ, 2021) examined the efficacy of screening by CBE in downstaging breast cancer at diagnosis and in reducing mortality

METHODS:

• Prospective, cluster randomized controlled trial
• Setting
  • 20 geographically distinct clusters located in Mumbai, India over 20 years (May 1998 to March 2019)
    • 10 clusters were designated as screening clusters, and 10 as controls
• Participants
  • Women aged 35 to 64
  • No history of breast cancer
• Interventions
  • Screening
    • 4 screening rounds of clinical breast examination (conducted by trained female primary health workers) and cancer awareness every two years
    • Followed by five rounds of active surveillance every two years
  • Control
    • One round of cancer awareness
    • Followed by eight rounds of active surveillance every two years
• Health workers who performed CBE
  • Passed 10th grade education
  • Training period of approximately 4 weeks
• Primary outcomes
  • Downstaging of breast cancer at diagnosis
  • Reduction in mortality from breast cancer

RESULTS:

• Screening arm: 75,360 women | Control arm: 76,178 women
• Breast cancer was detected at an earlier age in the screening group (P = 0.01)
  • Screening: mean age 55.18 years
  • Control: 56.50 years
• There was a significant reduction in the proportion of women with stage III or IV disease in the screening group (P = 0.001)
  • Screening: 37%
  • Control: 47%
• 15% reduction in breast cancer mortality was observed in the screening arm but was non-significant (P = 0.07)
  • Screening: 20.82 deaths/100,000 person years (95% CI, 18.25 to 23.97)
  • Control: 24.62 (95% CI, 21.71 to 28.04)
  • Rate ratio 0.85 (95% CI, 0.71 to 1.01)
• There was a reduction in breast cancer mortality in women aged ≥50 on post-hoc analysis (P = 0.02)
  • Screening: 24.62 deaths/100,000 person years (95% CI, 20.62 to 29.76)
  • Control: 34.68 (95% CI, 27.54 to 44.37)
  • Rate ratio 0.71 (95% CI, 0.54 to 0.94)
• There was no significant reduction in women <50 (P = 0.37)
• There was no difference in all cause mortality between groups (P = 0.49)
  • Rate ratio 0.95 (95% CI, 0.81 to 1.10)
  • Authors note that “because breast cancer deaths comprise less than 3% of all deaths in women in India, we did not expect a reduction in all cause mortality in our study”

CONCLUSION:

• Clinical breast examination led to a significant downstaging of breast cancer at diagnosis
• While a 15% reduction in overall breast cancer mortality was not significant, there was a significant 30% reduction in women over 50 years of age
• The authors conclude that clinical breast examination is a viable screening option for low- and middle-income countries

Learn More – Primary Sources:

Effect of screening by clinical breast examination on breast cancer incidence and mortality after 20 years: prospective, cluster randomised controlled trial in Mumbai

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