[An audit of breast cancer screening mammograms and the variability of radiological practice]

To audit the breast cancer screening mammograms performed in a general hospital and to assess the variation in medical practice in the diagnostic process.

A review was carried out on the screening mammograms performed between 1 May 2010 and 30 April 2011, with clinical follow up for two years, and a comparison with the published standards.

Of the 3,878 women examined, 368 (9.48%) were called back to complete the study (97 [16.1%] in the initial screening and 271 [8.2%] in revisions). Forty three biopsies (1.1%) were indicated, of which 24 were diagnosed with cancer. The positive predictive value (PPV) in screening studies (PPV1) was 6.52%. For the recommended biopsy (PPV2) it was 55%, with a sensitivity of 100%, a specificity of 91% and a cancer detection rate of 6.1/1,000. There were no false negatives. Twenty tumours were invasive; with no axillary lymph node infiltration was observed 15 of them. In 6 cases, the size of the tumour was less than or equal to 10mm, and in 17 it was less than 15mm. There were a higher percentage of new appointments by two radiologists (12% and 17.2% versus 7.3%) (P<.001). In 217 cases (58.96%; P<.001) only one radiologist indicated new appointments. Of this group, 73% were discharged in the first visit, compared to 47.6% in the non-discrepant group (P<.001). Four of the cancers were detected in these 217 patients.

The observed results are adjusted to the reference values. The discordant data are the new appointments rate, both in the initial screening and in the review, with a significant variation depending on the radiology reader.