Breast cancer screening still saves lives

Breast cancer affects approximately 11,000 women in Belgium each year. Of these, about 20% are younger than 50, and about 38% are 70 or older. Survival rates are good to very good when the disease is detected early. Currently, only women between the ages of 50 and 69 are invited to participate in biennial breast cancer screening through the Breast Cancer Screening Program, an initiative launched by the Flemish Government exactly 25 years ago. In recent years, the Belgian Cancer Registry has shown a slight increase in breast cancer among younger women. Because they are not included in the screening program, breast cancer is diagnosed at a later stage on average. The same is true for older women. Since women in their 70s are no longer invited for screening mammograms, they become less attentive to the warning signs of breast cancer. For this reason, the European Commission Initiative on Breast Cancer proposes expanding screening to the 45- to 74-year-old age group. The Federal Knowledge Center for Health Care (KCE) advises against this expansion based on its new study. Any woman can, upon referral from her primary care physician or gynecologist—who can take personal risk factors into account, such as a family history of the disease—undergo a mammogram. It is also important to make women aware of the warning signs of breast cancer (a lump in the breast, an inverted nipple, nipple discharge, etc.), because most breast cancers are detected by the women themselves.

A Chilling Message

Breast cancer screening has a number of benefits: it reduces breast cancer mortality, and thanks to the increased likelihood of early diagnosis, the number of disfiguring mastectomies is decreasing. However, in its communication about its new report, the KCE primarily emphasizes the drawbacks of screening. In the July 9 edition of *De Standaard*, we read that even for women between the ages of 50 and 69, the disadvantages of screening are greater and the benefits smaller than previously thought. It is said to be cost-ineffective; aggressive cancers often outpace the screening process; and screening detects tumors that do not require treatment. Moreover, 30% of all treatments (surgery, radiation, chemotherapy, hormone therapy, etc.) following screening are reportedly unnecessary. Overtreatment is a problem with any screening program, but 30% is a shockingly high figure.

The report further states that it is based on old to very old studies (from the 1960s to the 1990s) for which the certainty of the evidence is low to very low. Regarding two Canadian studies from the 1980s that were included, Canadian researchers even recommended in 2021 that these studies be disregarded in new guidelines on breast cancer screening due to bias. Incidentally, the report is critical of recent observational studies that would better reflect current screening and treatment realities, but these, in turn, were not included due to bias. The KCE report therefore rightly states in its conclusion that the evidence provided by the figures is limited and uncertain. The press release also mentions this: “We are not at all certain about the extent of the benefits and harms of the current breast cancer screening program, because the studies on which it is based are outdated and of moderate quality.”

Old wine in a new bottle

The new report is based on the same methodologically weak studies as the 2014 KCE report on breast cancer screening, including the two Canadian studies, but the tone of the reporting has changed. While in 2014 the emphasis was on the need to clearly inform women in the target group about the benefits and risks of breast cancer screening, the focus has shifted to overdiagnosis in 2026. The estimated rate of overdiagnosis in breast cancer screening for women aged 50 to 69 varies widely depending on the screening method used, as we have found in the relevant literature. Most figures range from 11 to 19 percent of diagnosed breast cancers based on randomized controlled trials (RCTs) and are less than 10 percent based on observational studies. Despite the overdiagnosis, there is still a net benefit in terms of survival.

Studies are currently underway to determine the extent to which personalized screening programs—in which screening is tailored to individual risk—could replace universal screening. There are also studies examining the impact of AI on screening diagnostics using more advanced mammography equipment. These results may shed new light on breast cancer screening.

Marleen Finoulst, physician at Pink Ribbon

Jan Lamote, breast surgeon and chair of the Board of Directors of Pink Ribbon

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