What is the point: will screening mammography save my life?

Area of Science:

• Oncology
• Preventive Medicine
• Biostatistics

Background:

• The claim that mammography saves lives is widely accepted.
• This study quantifies the absolute life-saving benefit of screening mammography in reducing breast cancer mortality.

Purpose of the Study:

• To calculate the absolute benefit of screening mammography in reducing breast cancer mortality.
• To determine the number of women needed to be screened to save one life.

Main Methods:

• Estimated screen-free absolute breast cancer death risk.
• Calculated absolute risk reduction and number needed to screen.
• Varied relative risk reduction (10%-30%) based on randomized trials.

Main Results:

• Repeated screening starting at age 50 saves approximately 1.8 lives per 1000 women over 15 years (20% relative risk reduction).
• The number needed to screen repeatedly is 570; survival increases from 99.12% to 99.29%.
• A single mammogram saves one life for every 2970 women screened, and 4.3% of screen-detectable cancers result in a life saved.

Conclusions:

• The absolute benefit of screening mammography increases with age.
• The number of events needed to save a life varies by screening subset.
• Less than 5% of women with screen-detectable cancers have their lives saved by mammography.