Breast screening, prognostic factors and survival - results from the Swedish two county study
1991

Breast Screening and Survival: Results from the Swedish Two-County Study

Sample size: 1582 publication Evidence: high

Author Information

Author(s): S.W. Duffy, L. Tabar, G. Fagerberg, A. Gad, O. Gr6ntoft, M.C. South, N.E. Day

Primary Institution: MRC Biostatistics Unit

Hypothesis

How do prognostic factors like tumor size, nodal status, and malignancy grade relate to breast cancer screening and survival?

Conclusion

The study found that screening significantly improves survival rates by detecting cancers at an earlier stage.

Supporting Evidence

  • Screening reduces the rates of larger tumors and metastases.
  • Malignancy grade worsens as tumor size increases.
  • Screen-detected cancers have better survival rates compared to those detected in interval screenings or control groups.

Takeaway

This study shows that getting regular breast cancer screenings can help doctors find tumors earlier, which can lead to better survival rates.

Methodology

Data from the Swedish two-county trial of mammographic screening for breast cancer was analyzed, focusing on women aged 40-69.

Potential Biases

Differences in malignancy grade assessment between pathologists could introduce bias.

Limitations

The study did not include tumors in situ and relied on histological examination, which may have subjective biases.

Participant Demographics

Women aged 40-69, with good compliance to screening.

Statistical Information

P-Value

p<0.0001

Statistical Significance

p<0.05

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