Mammography (X-ray examination) is an important method for breast cancer screening. The positive significance of screening for early diagnosis and treatment and improving survival rates has also been supported by a large number of studies.
However, there is still a controversial question: which age range is best for breast cancer screening?
On the one hand, young women’s breasts are denser, which will affect the sensitivity of mammography; secondly, the overall incidence and death rates of young women are lower; but at the same time, there is evidence that once young women have breast cancer, they may progress faster and The prognosis is worse.
For breast cancer screening (organized program for women of the right age), it is recommended to start at 40-50 years old internationally, and different guidelines are not completely consistent. The International Agency for Research on Cancer (IARC) breast cancer screening guidelines affirm the effect of mammography on women over 50 years old, and for women aged 40 to 49 years old, the existing evidence is considered limited.
Recently, the final results of the 23-year follow-up of 160,000 people in the UK Breast Cancer Age trial were published in The Lancet-Oncology. The results show that the age of group screening to 40 years old may reduce mortality without increasing overdiagnosis. After the research was published, many discussions were triggered, and the impact on clinical practice may not be so simple.
This randomized controlled trial started in 1990. During 1990-1997, more than 160,000 British women aged 39-41 were randomly assigned to 1:2 and received different invitations: from joining the study (ie 39-41 years old) Start to conduct mammography screening once a year; or follow the routine recommendations of the National Screening Program of the National Health Service (NHS) of the United Kingdom until they are 50 years old before starting screening.
The latest 23-year follow-up results show that in the 10 years before the study follow-up, that is, when women are 40-49 years old, receiving annual screening, breast cancer mortality can be significantly reduced by 25%. But with the extension of follow-up time, the difference in breast cancer mortality between the two groups was no longer significant.
(Cumulative mortality of breast cancer diagnosed during the study period. Women who started screening at about 40 years old (red line) have a lower risk of breast cancer death before the age of 50; the absolute difference in mortality between the two groups stabilized after the age of 50)
Lead researcher, Professor Stephen Duffy of Queen Mary University of London, said: "This study confirms that the benefits of screening women under 50 are mainly reflected in the first ten years; in the long run, the mortality rate The reduction in the rate can also be maintained, which is equivalent to 1 in every 1,000 women screened will be saved."
The results also suggest that compared with the beginning of screening at the age of 50, receiving screening at the age of 40-49 did not lead to an increase in overdiagnosis. During the study period, there was no significant difference in the total incidence of breast cancer between the two groups of women, including the incidence of invasive breast cancer. During the 40-49 years of age, the intervention group reported more cancers in situ, but this gap was also narrowing, and there was no difference between the two groups at the end of the 23-year follow-up.
The research team pointed out that “the worst case is a moderate overdiagnosis. Breast cancer that is'overdiagnosed', even if it is not detected between the ages of 40-49, will be diagnosed in the screening from the age of 50.”
Based on these data, the research team believes that reducing the minimum age for screening from 50 to 40 may help reduce breast cancer mortality.
However, in the discussion of the paper, the research team also pointed out that compared with the 1990s when the trial started, the current breast cancer diagnosis and treatment are no longer the same. On the one hand, advances in therapy may reduce the scope of screening benefits; on the other hand, more cutting-edge screening equipment may be more conducive to early detection, and recent results still support that early diagnosis and treatment can bring huge survival benefits. beneficial. Therefore, it is still necessary to evaluate the impact of the latest breast cancer screening technologies and treatment options on women under 50.
REFERENCE:
Daniel Vulkan, et al., (2020). Effect of mammographic screening from age 40 years on breast cancer mortality (UK Age trial): final results of a randomised, controlled trial. The Lancet Oncology, DOI: https://doi.org/10.1016/S1470-2045(20)30398-3