Screening for breast cancer with mammography

Area of Science:

• Oncology
• Public Health
• Radiology

Background:

• Mammographic screening for breast cancer has varying estimates of benefits and harms.
• National policies on mammography screening differ.
• Assessing the true impact of screening is crucial for informed healthcare decisions.

Purpose of the Study:

• To evaluate the effect of mammographic screening on breast cancer mortality and morbidity.
• To analyze data from randomized controlled trials comparing screening with no screening.

Main Methods:

• Systematic search of PubMed database up to June 2005.
• Inclusion of randomized trials comparing mammographic screening versus no screening.
• Independent data extraction by authors and contact with study authors for additional information.

Main Results:

• Seven eligible trials involving 500,000 women were analyzed, excluding a biased trial.
• High-quality trials showed no significant reduction in breast cancer mortality (RR 0.93).
• Lower-quality trials indicated a significant reduction (RR 0.75), but this was deemed unreliable due to biased cause-of-death classification; screening increased surgical procedures and radiotherapy.

Conclusions:

• Mammographic screening likely reduces breast cancer mortality, with an estimated 15% relative risk reduction in high-quality trials.
• Screening results in overdiagnosis and overtreatment, increasing the absolute risk by 0.5%.
• The balance of benefits and harms is unclear, necessitating informed consent regarding both advantages and disadvantages for women undergoing screening.