Question

Should mammography screening be lowered to the age of 40 and 50 years?

Recommendation

Mammography screening in women between the age of 40 and 50 has not shown a statistically significant reduction in mortality.

Conclusions

Mammography screening in women between the age of 40 and 50 showed a 15-17% reduction in mortality in the intervention arm compared to the control arm. This difference was not statistically significant.

A 24% reduction was calculated for the women who participated fully in the program.

Level 3: A2 Moss 2006

Literature summary

Lowering the screening age to 40-50 years: what are the pros and cons?

Screening women between age 40 and 50 is controversial. In 2002 the USPSTF stated that there was sufficient evidence to recommend annual mammograms [Qaseem, 2007], but in their 2009 publication [USPSTF, 2009] they no longer recommended it. This change was in response to the results of a study on risk models by Mandelblatt (2009) reporting just 3% more mortality reduction in this group (range 1% to 6%) than screening in the age category from 50 to 75 years. The harm (high costs and high percentage of false-positive results) exceeds the benefits. They state that the decision to move to annual screening should be made on an individual basis, weighing up the benefits against the potential harm.

In 2006 the results were published from a randomised study on screening in ages 40 to 49 (basic assumption: reduction in mortality) which had a convincing design and adequate power; the study was initiated in 1991 in the United Kingdom [Moss, 2006]. The statistics appear to be consistent with previous studies [Moss, 2005]: in women between ages 40 and 49 invited for screening, the breast cancer diagnosis was made earlier than in women who were not invited [Moss, 2006]. In Moss's study, a 17% reduction was reached after an average follow-up of 10.7 years. This number did not turn out to be statistically significant, however. When corrected for non-compliance (entirely or partly refraining from participation) a 24% reduction in mortality was calculated. The turnout was 68% in the first round and 70% in the follow-up rounds; in total 81% had at least one screening mammogram.

In the accompanying editorial it was suggested that the trend toward reduced mortality was confirmed, but that there is still too much uncertainty about the adverse effects, such as unjustified reassurance, false-positive exams and cancer induction from radiation [Djulbegovic, 2006].

Considerations

In the Netherlands, women between 50 and 75 years of age are currently screened through the national breast cancer screening programme. The upper age limit recommended by the Netherlands Health Council is partly based on the fact that the disease occurs in 75% of women above 50 years of age. The question is whether screening should be expanded to include younger age groups. According to the National breast cancer screening Act, before the screening can be expanded the Dutch Ministry of Health would need to issue a permit based on the recommendation of the Health Council (http://www.rijksoverheid.nl/onderwerpen/bevolkingsonderzoek). However, the Centre for Population Screening of the RIVM (National Institute for Public Health and the Environment) is giving priority to other screening activities at the moment.

 

Gradual change in diagnostics in the later stages

The advent of screening involves a considerable number of non-palpable abnormalities. Developments in hospitals have mainly focused on rapid diagnosis (breast clinics) and on obtaining a definitive preoperative diagnosis using minimally invasive ultrasound-guided or stereotactic-guided procedures, partly through participation in projects such as the Breakthrough Project. The ultimate percentage of patients who undergo unnecessary surgery as a result of screening is much lower now compared to the approach used in the period the foundation for the screening was laid. Based on the quality criteria currently being used (NABON note: Manual for the Organisation of Breast Cancer Care, www.NABON.nl), it can be inferred that a preoperative diagnosis should be possible in 90% of the cases.

 

Experience and policy elsewhere

Of the 19 members of the International Breast Cancer Screening Network, only Iceland, Uruguay, Sweden and the United States start screening at age 40, and in fact in the US they are now debating whether to raise this starting age again [USPSTF, 2009; Mandelblatt, 2009]. Uruguay and the United States screen annually, the United Kingdom once every 3 years, and the other member states once every 2 years.

Authorization date and validity

Last review : 13-02-2012

Last authorization : 13-02-2012

Initiative and authorization

Initiative : Nationaal Borstkanker Overleg Nederland

Authorized by:
  • Nederlandse Internisten Vereniging
  • Nederlandse Vereniging voor Heelkunde
  • Nederlandse Vereniging voor Pathologie
  • Nederlandse Vereniging voor Radiologie
  • Nederlandse Vereniging voor Radiotherapie en Oncologie