National Performance Indicators for the Breast Cancer Screening Program for the 2013–2014 Period
Download the tables of all national indicators for the combined years 2013 and 2014, broken down by rank (xls - pdf).
Download the tables of key indicators broken down by technology type for the combined years 2013 and 2014, by rank (xls - pdf).
The organized breast cancer screening program aims to detect the disease at an early stage so it can be treated as soon as possible, with the goal of reducing breast cancer-specific mortality. To maximize benefits and minimize risks—that is, to be effective—an organized screening program must be of high quality. It must therefore be evaluated. Here we present the performance indicators for the organized breast cancer screening program for the 2013–2014 period.
Data from all screenings performed as part of the organized screening program across all departments (a total of 98, with the two departments in Corsica evaluated together and Department 04 unable to submit its data this year) were included to form the 2013–2014 national database.
Since women are invited to undergo breast cancer screening via mammography every two years, the results are presented over a cumulative two-year period. During this 2013–2014 period, 4,964,925 screenings were performed. It should be noted that the overall results summarized here mask significant geographic disparities, as can be seen by examining the results by department.
Quality Indicators (Screening Results)
The figures provide information on the number of women screened, screening results, and diagnostic evaluations for the 2013–2014 period. Indicators T02 through T05 and P07 through P09 present the corresponding rates and percentages.
For the 2013–2014 period, 4% of screenings were first organized screenings with no prior mammography history (hereinafter referred to as “true initial screening”), 14% were first organized screenings with a history of mammography (most often as part of opportunistic screening), and 82% were subsequent screenings.
The rate of positive mammograms (i.e., those judged abnormal or suspicious) on first reading (L1) prior to further evaluation is 14 per 100 women undergoing a “true” initial screening. For women undergoing a follow-up screening, this rate is 6.5. An immediate diagnostic workup (BDI) is then performed in 96.7% of cases.
The rate of positive mammograms on the second reading (R2) is 1.9 per 100 women undergoing a "true" initial screening. For women undergoing a follow-up screening, this rate is 1.1 per 100 women. A deferred diagnostic evaluation (DDE) is performed in 82% of cases.
Ultimately, the rate of positive mammograms on first or second reading prior to evaluation (equivalent to the “European recall rate”) is 15.7 per 100 women undergoing a “true” initial screening and 7.5 per 100 subsequent screenings. The rate of positive screenings after further evaluation (BDI or BDD) is 7.9% for “true” initial screenings and 3.1% for subsequent screenings.
All of these results are stable compared to the 2011–2012 period.
Early program effectiveness indicators (cancer detection)
The figures provide information on the number of cancers detected and their characteristics for the 2013–2014 period. The TC01 and PC02 through PC10 indicators present the corresponding rates and percentages.
At the time of data extraction, 36,889 cancers (invasive cancers and ductal carcinoma in situ) had been recorded for the 2013–2014 period, representing an overall rate of 7.4 cancers per 1,000 women screened. This rate is 12.9 per 1,000 women undergoing an "initial" screening and 7.1 per 1,000 subsequent screenings. These rates are very close to those for the 2011–2012 period.
The percentages of cancers with a favorable prognosis among all detected cancers are important indicators for evaluating the program’s performance:
Among women undergoing a "true" initial screening, 11.4% of cancers with known invasive/in situ status were in situ cancers, 21.2% of cancers with known size were 10 mm or smaller, and 62.1% of cancers with known lymph node status had no lymph node involvement.
Among women undergoing follow-up screening, 15.2% of cancers with known invasive/in situ status were in situ cancers, 39.3% of cancers with known size were 10 mm or smaller, and 78.2% of cancers with known lymph node status had no lymph node involvement.
Finally, among 100 cancers detected in 2013–2014, 2.8 were detected through the second reading among women undergoing a “true” initial screening and 6.4 among those undergoing follow-up screenings. These percentages are slightly lower than those for the 2011–2012 period.
Positive Predictive Value (PPV)
The indicators represent the positive predictive values (PPV) before and after diagnostic evaluations. Calculating the positive predictive values of screening within the screening program requires knowing the outcome of the screening procedure. At the time of data transmission to Santé publique France, this information may be either definitive (cancer, normal, benign, woman definitively lost to follow-up or deceased) or provisional (pending diagnosis or woman under clinical surveillance). At the time of analysis, the information was definitive for 98.8% of screened women, and for 92.8% of women who had positive screening results prior to diagnostic evaluation.
The PPV of screening mammography prior to diagnostic evaluation (PPV01 indicator from the Screening Indicators Guide), i.e., the probability of having cancer if the screening mammogram is positive on the first or second reading, prior to diagnostic evaluation (immediate or delayed), is 8.7%.
The PPV of the screening process completed in full—that is, the probability of having cancer if the diagnostic evaluation (delayed or immediate) is positive—is 20%.
These two PPVs are stable compared to the 2011–2012 period.
Digital Mammography
Since 2008, digital mammography has been authorized in the national program in addition to analog technology. Two main types of digital technologies are used: full-field (digital radiography, DR) and fluorescent screens (computer radiography, CR). During the 2013–2014 period, 89% of screenings were performed using digital technology, broken down into 36% CR and 64% DR. The share of DR technology is higher and has increased compared to the 2011–2012 period. The rate of technically correct images is nearly 100% for all three technologies.
The crude positivity rates on first reading prior to further evaluation, as well as the rates of detected cancers, are higher for digital than for analog. And among digital methods, these rates are higher for DR than for CR. Consequently, the contribution of the second reading appears to be lower with DR digital technology, since the rate of positive mammograms on second reading prior to evaluation and the percentage of cancers detected by the second reader among all detected cancers are lower. These results are observed regardless of the screening stage.
If we focus solely on subsequent rounds—that is, 82% of screenings from the 2013–2014 period—we observe that the percentages of cancers with a good prognosis are higher with digital technology, and particularly with digital DR. These better results for DR are also observed for “true” initial screenings, except for the rate of in situ cancer. The PPVs of positive screenings prior to further evaluation are higher.
It should be noted that the differences observed between the three types of mammography do not correspond solely to differences in technological performance: confounding factors, notably the experience of radiologists, also play a role.
