More on screening mammography

Cumulative risks of false positive recall and screen-detected breast cancer after multiple screening examinations

Women tend to make a decision about participation in breast cancer screening and adhere to this for future invitations. Therefore, our study aimed to provide high-quality information on cumulative risks of false-positive (FP) recall and screen-detected breast cancer over multiple screening examinations. Individual Dutch screening registry data (2005-2018) were gathered on subsequent screening examinations of 92 902 women age 49 to 51 years in 2005. Survival analyses were used to calculate cumulative risks of a FP and a true-positive (TP) result after seven examinations. Data from 66 472 women age 58 to 59 years were used to extrapolate to 11 examinations. Participation, detection and additional FP rates were calculated for women who previously received FP results compared to women with true negative (TN) results. After 7 examinations, the cumulative risk of a TP result was 3.7% and the cumulative risk of a FP result was 9.1%. After 11 examinations, this increased to 7.1% and 13.5%, respectively. Following a FP result, participation was lower (71%-81%) than following a TN result (>90%). In women with a FP result, more TP results (factor 1.59 [95% CI: 1.44-1.72]), more interval cancers (factor 1.66 [95% CI: 1.41-1.91]) and more FP results (factor 1.96 [95% CI: 1.87-2.05]) were found than in women with TN results. In conclusion, due to a low recall rate in the Netherlands, the cumulative risk of a FP recall is relatively low, while the cumulative risk of a TP result is comparable. Breast cancer diagnoses and FP results were more common in women with FP results than in women with TN results, while participation was lower.

Online information about risks and benefits of screening mammography in 10 European countries: An observational Web sites analysis

Most publications about breast cancer do not provide accurate and comprehensive information, giving few or no data about risk/benefit ratios. We conducted a comparative study among 10 European countries about health information on breast cancer screening, assessing the first 10 Web sites addressing the general public that appeared following an Internet search.With the help of medical residents involved in the EuroNet MRPH Association, we analyzed the first 30 results of an Internet search in 10 European countries to determine the first 10 sites that offered screening mammography. We searched for the following information: source of information, general information on mammography and breast cancer screening, potential harms and risks (false positives, false positives after biopsy, false negatives, interval cancer, overdiagnosis, lead-time bias, and radiation exposure), and potential benefits (reduced mortality and increased survival).The United Kingdom provided the most information: 39 of all 70 possible identified risks (56%) were reported on its sites. Five nations presented over 35% of the possible information (United Kingdom, Spain, France, Ireland, and Italy); the others were under 30% (Portugal, Poland, Slovenia, Netherlands, and Croatia). Regarding the benefits, sites offering the most complete information were those in France (95%) and Poland (90%).Our results suggest that, despite consensus in the scientific community about providing better information to citizens, further efforts are needed to improve information about breast cancer screening. That conclusion also applies to countries showing better results. We believe that there should be greater coordination in this regard throughout Europe.

Scarce information about breast cancer screening: An Italian websites analysis

Although the public should have complete and correct information about risk/benefit ratio of breast cancer screening, public knowledge appears generally scarce and oriented to overestimate benefits, with little awareness of possible disadvantages of the screening.We evaluated any document specifically addressed to the general female public and posted on internet by Italian public health services. The presence of false positive, false positive after biopsy, false negative, interval cancer, overdiagnosis, lead-time bias, exposure to irradiation, and mortality reduction was analyzed.Of the 255 websites consulted, 136 (53.3%) had sites addressed to the female public. The most commonly reported information points were the false-positive (30.8% of sites) and radiation exposure (29.4%) rates. Only 11 documents mentioned overdiagnosis, 2 mentioned risk of false positive with biopsy, and only 1 mentioned lead-time bias. Moreover, only 15 sites (11.0%) reported quantitative data for any risk variables.Most documents about breast cancer screening published on the web for the female public contained little or no information about risk/benefit ratio and were biased in favor of screening.

Comparison of cumulative false-positive risk of screening mammography in the United States and Denmark

INTRODUCTION

In the United States (US), about one-half of women screened with annual mammography have at least one false-positive test after ten screens. The estimate for European women screened ten times biennially is much lower. We evaluate to what extent screening interval, mammogram type, and statistical methods, can explain the reported differences.

METHODS

We included all screens from women first screened at age 50-69 years in the US Breast Cancer Surveillance Consortium (BCSC) (n=99,455) between 1996-2010, and from two population-based mammography screening programs in Denmark (n=230,452 and n=400,204), between 1991-2012 and 1993-2013, respectively. Model-based cumulative false-positive risks were computed for the entire sample, using two statistical methods (Hubbard Njor) previously used to estimate false-positive risks in the US and Europe.

RESULTS

Empirical cumulative risk of at least one false-positive test after eight (annual or biennial) screens was 41.9% in BCSC, 16.1% in Copenhagen, and 7.4% in Funen. Variation in screening interval and mammogram type did not explain the differences by country. Using the Hubbard method, the model-based cumulative risks after eight screens was 45.1% in BCSC, 9.6% in Copenhagen, and 8.8% in Funen. Using the Njor method, these risks were estimated to be 43.6, 10.9 and 8.0%.

CONCLUSION

Choice of statistical method, screening interval and mammogram type does not explain the substantial differences in cumulative false-positive risk between the US and Europe.

Breast cancer mortality in participants of the Norwegian Breast Cancer Screening Program

BACKGROUND

The Norwegian Breast Cancer Screening Program started in 1996. To the authors' knowledge, this is the first report using individual-based data on invitation and participation to analyze breast cancer mortality among screened and nonscreened women in the program.

METHODS

Information on dates of invitation, attendance, breast cancer diagnosis, emigration, death, and cause of death was linked by using unique 11-digit personal identification numbers assigned all inhabitants of Norway at birth or immigration. In total, 699,628 women ages 50 to 69 years without prior a diagnosis of breast cancer were invited to the program from 1996 to 2009 and were followed for breast cancer through 2009 and death through 2010. Incidence-based breast cancer mortality rate ratios (MRRs) were compared between the screened and nonscreened cohorts using a Poisson regression model. The MRRs were adjusted for calendar period, attained age, years since inclusion in the cohorts, and self-selection bias.

RESULTS

The crude breast cancer mortality rate was 20.7 per 100,000 women-years for the screened cohort compared with 39.7 per 100,000 women-years for the nonscreened cohort, resulting in an MRR of 0.52 (95% confidence interval, 0.47-0.59). The mortality reduction associated with attendance in the program was 43% (MRR, 0.57; 95% confidence interval, 0.51-0.64) after adjusting for calendar period, attained age, years after inclusion in the cohort, and self-selection bias.

CONCLUSIONS

After 15 years of follow-up, a 43% reduction in mortality was observed among women who attended the national mammographic screening program in Norway.

Balancing harms and benefits of service mammography screening programs: a cohort study

INTRODUCTION

The use of screening mammography is still under debate within the medical community. The aim of this study is to define a balance sheet of benefits (breast cancer mortality reduction) and harms (overdiagnosis) for mammography screening programs.

METHODS

We compared breast cancer incidence and mortality in two cohorts of women, defined as 'attenders' or 'non-attenders' on the basis of the individual attitudes towards screening, who were invited to the first round of the Florentine screening program. The effects of screening exposure on breast cancer incidence and mortality were evaluated by fitting Poisson regression models adjusted for age at entry, marital status and deprivation index. We performed a sensitivity analysis excluding 34 women not responding to the invitation with a breast cancer diagnosis in the following six months.

RESULTS

In total, we included 51,096 women aged 50 to 69 years invited at the first screening round (1991 to 1993) and followed-up for breast cancer incidence and mortality until 31 December 2007 and 31 December 2008, respectively The estimate of mortality reduction varies from 45% among 50 to 59 year-old women up to 51% among 60 to 69 year-old women. The estimate of overdiagnosis, according to the cumulative-incidence method, is an additional 10% of all breast cancer cases among 60 to 69 year-old women screened.

CONCLUSIONS

Comparing the breast cancer mortality and breast cancer incidence between attenders and non-attenders, we have determined that the overall cost to save one life corresponds to no more than one over-diagnosed tumor (from 0.6 to 1 depending on the selection criteria of the cohort), even if a residual self-selection bias cannot be excluded.