Screening for breast and prostate cancers: moving toward transparency

Area of Science:

• Oncology
• Preventive Medicine
• Biostatistics

Background:

• Early cancer screening trials reported mortality reductions, but recent population data show diminished benefits for breast and prostate cancer screening.
• Disease-specific mortality is often used as a surrogate endpoint in screening trials due to the large sample sizes required to detect all-cause mortality reductions.

Purpose of the Study:

• To analyze the discrepancy between expected and actual impacts of cancer screening programs.
• To highlight the role of overdiagnosis as a potential source of harm in cancer screening.

Main Methods:

• Review of recent population-based data on cancer screening outcomes.
• Analysis of the validity of disease-specific mortality as a surrogate for all-cause mortality in screening trials.

Main Results:

• Recent population data suggest that breast and prostate cancer screening have not achieved their anticipated benefits.
• Overdiagnosis, a recognized risk of screening, may lead to increased mortality from causes other than the targeted cancer.

Conclusions:

• The discrepancy between expected and actual cancer screening benefits may be explained by the limitations of disease-specific mortality as an outcome measure and the impact of overdiagnosis.
• Recognizing overdiagnosis as a source of harm is crucial for accurately assessing and projecting the impact of cancer screening programs.