For an average-risk breast cancer screening in a standard program, what interval is used?

• A. Every year
• B. Every 2 years
• C. Every 3 years
• D. Every 4 years

Answer: (C)

Screening intervals are set to balance detecting cancer early with the harms and costs of screening. For average-risk women in a standard program, the schedule used is screening every 3 years. This cadence reflects that breast cancers often progress over several years, so a 3-year interval can catch cancers at a treatable stage while avoiding the higher rates of false positives, follow-up procedures, and radiation exposure that come with more frequent screening. A yearly interval would increase these harms without proportionally improving outcomes for average risk, and while some programs screen more frequently (every 2 years), this particular standard program uses 3 years. Waiting 4 years would raise the chance of cancers developing and becoming less easily treated before the next screen.