Radiology review of the UKCCCR Breast Screening Frequency Trial: potential improvements in sensitivity and lead time of radiological signs.

ABSTRACT

AIM: To review all previous mammograms of breast cancer cases diagnosed during a randomized trial comparing 3 yearly to annual mammographic screening with a view to identifying and quantifying cases that might potentially have been diagnosed earlier. METHODS: Mammograms of 602 breast cancer cases (399 screen-detected and 203 interval cases) were reviewed in chronological order and suspicious radiological features noted for each mammogram, up to and including the diagnostic mammogram. RESULTS: Of the 602 cases, 79 (13%) had features at diagnosis that were visible on previous mammograms, suggesting a sensitivity of interpretation of 87%. A similar proportion of screen-detected (14%) and interval cancers (11%) had signs at diagnosis that were visible on previous mammograms. The potential for improvement was particularly noted for asymmetric density (sensitivity = 77%, average time visible before diagnosis 14 months) and parenchymal deformity/stellate lesion (sensitivity = 81%, average time visible before diagnosis 12 months). CONCLUSION: The highest sensitivity was observed for comedo-type microcalcifications (sensitivity = 97%, average time visible before diagnosis 5 months). By improvements in sensitivity to asymmetric density and parenchymal deformity/stellate lesion, 4% of tumours could have their time of diagnosis advanced substantially.