The benefits and harms of breast cancer screening: an independent review

TLDR: It is concluded that screening reduces breast cancer mortality but that some overdiagnosis occurs, and results from observational studies support the occurrence of over Diagnosis, but estimates of its magnitude are unreliable.

About: This article is published in The Lancet.The article was published on 2012-11-17 and is currently open access. It has received 1451 citations till now. The article focuses on the topics: Overdiagnosis & Breast cancer screening.

Figures

Figure 3. (A) Varying screen detection capability in relation to tumour growth rate (copied from Esserman et al, 2009). (B) Hypothetical cumulative incidence of breast cancer without (left) or with (right) overdiagnosis based on screening women between 50–68 years (copied from Biesheuvel et al, 2007; red line shows screened women and blue line unscreened women). (C) Meta-analysis of estimates of overdiagnosis: (a) excess cancers as a proportion of cancers diagnosed over whole follow-up period in women invited for screening, (b): excess cancers as a proportion of cancers diagnosed during screening period in women invited for screening. (D) Consequences of overdiagnosis.

Table 1. Characteristics of the randomised trials of breast cancer screening

Table 3. Comparison of public health interventions

Figure 2. Meta-analysis of the breast cancer screening trials: RR of breast cancer mortality after 13 years of follow-up. Adapted from the Cochrane Review (Gøtzsche and Nielsen, 2011). Note: Malmö II is excluded because follow-up approximating 13 years was not available; the Swedish Two County (Kopparberg and Östergötland) and Canada I and II trials are split into their component parts; the Edinburgh trial is excluded because of severe imbalances between randomised groups.

Figure 1. (A) European age-standardised incidence rates per 1 00000 population, females, by age, Great Britain. (B) Breast cancer mortality at ages 35–69, UK, 1950–2009 (World Health Organization, 2012).

Figure 4. The assessment process. Overall cancer detection rate is 583/75 057¼ 7.8 cancers per 1000 women screened. Of the 3105

Frequently asked questions

Q1. What are the contributions in "The benefits and harms of breast cancer screening: an independent review" ?

The Independent UK Panel on Breast Cancer Screening this paper concluded that women should be aware that screening carries a risk of detecting cancers, invasive and 

Q2. What are the future works mentioned in the paper "The benefits and harms of breast cancer screening: an independent review" ?

The panel ’ s review of the randomised trials of breast screening leads to the following recommendations about future research priorities: The panel ’ s review of overdiagnosis leads to their support for further research into DCIS, in particular: A proposed study to examine the need for treatment of lowgrade DCIS Continued support for the Sloane project, which has an extensive database of screen-detected cases of DCIS, and the long-term follow-up of these cases may well improve their understanding of this condition ( The Sloane Project 2010, 2011 ). 

Q3. How many women are invited to breast screening?

Of the B307 000 women aged 50–52 who are invited to screening each year, just 41% would have an overdiagnosed cancer during the next 20 years. 

Q4. How many deaths are prevented from breast cancer?

Estimates from trials of shorter duration suggest overdiagnosis of about 11% as a proportion of breast cancer incidence during the screening period and for the remainder of the woman’s lifetime, or equivalently about 19% as a proportion of cancers diagnosed during the screening period. 

Q5. What is the effect of screening on the public health?

The greater the proportion of women who accept the invitation to be screened, the greater is the benefit to the public health in terms of reduction in mortality from breast cancer. 

Q6. How many women were diagnosed with breast cancer during the screening period?

The frequency of overdiagnosis was of the order of 11% from a population perspective, and about 19% from the perspective of a woman invited to screening. 

Q7. How many women are screened every year?

The panel’s best estimate is that the breast screening programmes in the United Kingdom, inviting women aged 50–70 every 3 years, prevent about 1300 breast cancer deaths a year, a most welcome benefit to women and to the public health. 

Q8. What is the estimate of the benefit of breast screening?

The panel’s review of the evidence on benefit – the older RCTs, and those more recent observational studies – points to a 20% reduction in mortality in women invited to screening. 

Q9. What is the method used to determine the incidence of breast cancer?

One method that has been used is investigation of time trends in incidence rates of breast cancer for different age groups over the period that population screening was introduced. 

Q10. How many breast cancer deaths are prevented by screening?

for 10 000 women invited to screening, from age 50 for 20 years, it is estimated that 681 cancers (invasive and DCIS)2206 www.bjcancer.com |DOI:10.1038/bjc.2013.177will be diagnosed, of which 129 will represent overdiagnosis (using the 19% estimate of overdiagnosis) and 43 deaths from breast cancer will be prevented. 

Q11. What is the appropriate measure of benefit of breast screening?

The appropriate measure of benefit, therefore, is reduction in mortality from breast cancer in women offered screening compared with women not offered screening. 

Q12. How many deaths from breast cancer are prevented each year?

For the UK screening programmes, this currently corresponds to about 1300 deaths from breast cancer being prevented each year, or equivalently about 22 000 years of life being saved. 

Q13. How many women would need to be screened to prevent one breast cancer death?

This yielded the estimate that for every 235 women invited to screening, one breast cancer death would be prevented; correspondingly 180 women would need to be screened to prevent one breast cancer death. 

Q14. How many women are screened for breast cancer?

This corresponds to one breast cancer death averted for every 235 women invited to screening for 20 years, and one death averted for every 180 women who attend screening. 

Q15. How many women will be screened for breast cancer?

Putting together benefit and overdiagnosis from the above figures, the panel estimates that for 10 000 UK women invited to screening from age 50 for 20 years, about 681 cancers will be found of which 129 will represent overdiagnosis, and 43 deaths from breast cancer will be prevented.