There is a prejudice associated with this type of early cancer detection - mammography supposedly does more harm than good. We checked whether this opinion is supported by scientific evidence.

They write with reference to doctors and scientists that the negative effects of mammography can be more significant than the positive ones. Media And medical journals. Some publications are devoted to the problem of overdiagnosis and false positive results, and the authors of others, clickbait and even near-conspiracy theories articles claim that the procedure itself can cause cancer. Claims about the unsafety of this method, based on evidence of varying degrees of credibility, can be found in social networks And blogs.

Among women, breast cancer (BC) is most a common type of cancer and one of the leading causes of cancer mortality. According to WHO, in 2022, there were approximately 2.3 million new cases of breast cancer and approximately 670,000 associated deaths worldwide. The highest incidence rates are observed in developed countries in Europe and North America, while the number of new cases, on the contrary, is growing especially rapidly in low- and middle-income countries. Most often breast cancer identify in women over 50 years of age, but it has become “younger” in recent decades—for example, from 2001 to 2020, in more than 20 US states, the number of detected cases among women under 40 years of age grew by an average of more than 0.5% annually. According to experts, every 20th woman on the planet will develop this type of cancer during her lifetime.

The survival rate of patients with breast cancer, as with other oncological diseases, is largely depends depending on how early the tumor was discovered. If it has not spread beyond the breast, the five-year survival rate exceeds 99%, and if the lymph nodes are affected, it is 87%.

For early detection of malignant neoplasms, women are advised to regularly conduct self-examinations, as well as undergo screenings in clinics. For this apply one of three methods: ultrasound, MRI and mammography. The latter method is recommended by regulatory and specialized authorities in different countries - for example, in Russia, women aged 40 to 75 years are advised to have mammography every two years. European Society of Clinical Oncology recommends do it once every one to two years for women aged 50 to 69 years. American Cancer Society admits screening has been carried out since the age of 40 on the recommendation of a doctor and insists on it for women from 50 to 74 years old.

These recommendations are based on the idea that mammography is the most effective diagnostic method. In 2019, American researchers analyzed data on patients who, from 2000 to 2013, underwent either mammography, ultrasound, or both studies at once. Scientists have come to the conclusion that ultrasound diagnostics is at least optional both as the main screening method and as an additional one. If there really was a malignancy, it could be detected in either of two ways, with ultrasounds producing too many false positives, which caused women stress and provoked them to undergo unnecessary additional tests. On the other hand, this point of view refutes 2025 study. Chinese experts conducted a meta-analysis of available publications on screening by ultrasound and mammography and found that the first correctly identified the tumor in 88% of cases, and the second only in 76%. At the same time, when comparing different diagnostic methods, it should be taken into account that devices are constantly being improved (the screening accuracy on devices released ten years apart is noticeably different), and scientists can use the latest models from the manufacturer that sponsored the study, which in reality not all patients will have access to.

Part of the concern about the dangers of mammography is related to the fact that X-ray radiation is used during the procedure - supposedly it can provoke breast cancer (especially taking into account the recommendations for regular such diagnostics). In fact, with mammography apply low-dose radiation, that is, the dose of radiation is even less than, for example, when taking an x-ray of a person with a suspected fracture. Such diagnostics are strictly prohibited only for pregnant and lactating women; alternatively, they can use ultrasound or MRI.

Experts' doubts about mammography are not related to radiation or inefficiency, but to the justification for the widespread use of this diagnostic method. American physician and popularizer of evidence-based medicine Paul Offit in his book “Pandora’s Box” explains: “The very definition of cancer is changing, and not for the better. Medical textbooks 20 years ago defined it as “a disease whose natural course is fatal.” This is no longer the case. Now non-fatal types of cancer have been discovered, when a person dies with them rather than from them. And in the process of discovering these non-fatal cancers, we are doing more harm than good."

Offit suggests using the classification of cancer diseases proposed by Dartmouth College Medical School professor Gilbert Welch. He compares cancers to farm animals and screening to a pen gate. Cancers that are likely to kill a person regardless of whether they are detected (for example, pancreatic cancer), Welch likens it to a bird that will fly over a gate regardless of whether it is open or not. Tumors from which patients do not die (among them some types of prostate cancer) can be compared to a turtle - so slow that it is unlikely to escape even with an open gate. Finally, the third type of cancer within Welch’s metaphor is similar to a rabbit: if the gate is open (that is, screening is not carried out), he can quickly escape (that is, the disease will become deadly), if it is closed, he will not be able to do this. In other words, if we follow Welch’s analogy, diagnosis will be most effective specifically for cancer of this third type.

The challenge is to understand whether breast cancer is one of these diseases. In 2012, Welch, along with his colleague Archie Bleier published an article in which he compared data on the detection of breast cancer in the United States from 1976 to 2008 with data on mortality from it for the same period. They found that the number of detected cases of breast cancer during this time increased from 112 to 234 per 100,000 women, while the number of cases detected at a late, deadly stage fell from 102 to 94. According to the researchers, we are talking about mass overdiagnosis, that is, situations when patients hear a frightening diagnosis and undergo corresponding heavy treatment for a disease that would never kill them. Welch and Bleier estimated that as many as 70,000 women in the United States may have found themselves in this situation in 2008 alone. “Until scientists can find genetic or biochemical markers that can clearly distinguish dangerous cancers from non-dangerous ones, we will continue to suffer from overdiagnosis and overtreatment of cancers that are not really cancer at all,” Offit comments on these calculations.

It is also significant study, conducted in 2015. American scientists suggested that in districts where more women undergo mammography, there should be fewer deaths from late-diagnosed breast cancer, and decided to test this hypothesis using statistical data. The sample included 16 million women from 547 districts. In counties with greater screening coverage, significantly more cancer cases were identified and more follow-up studies were conducted, but the mortality rate from breast cancer was the same as in counties where far fewer women were screened. Moreover, in patients from districts with good diagnostics, small and non-aggressive tumors prevailed, while large tumors with a poor prognosis were detected equally often, regardless of the popularity of diagnostic measures. Scientists have found that mammography leads to widespread overdiagnosis.

Similar conclusion done and their Canadian colleagues in a paper published a year earlier. As part of the study, nearly 90,000 women were randomly divided into two groups: the first group underwent annual mammography for 25 years, and the second group received a manual breast examination. The groups did not differ statistically either in the number of detected cases of breast cancer or in the number of deaths from breast cancer. At the same time, women from the first group were 30% more likely to resort to surgical and other treatment methods. Experts have concluded that regular examination and palpation by a specialist is sufficient to identify dangerous breast tumors.

In 2015, science journalist Christy Aschwanden told its story on the pages of the specialized Journal of the American Medical Association. When she was offered a screening mammogram, the doctor did not explain the pros and cons of the procedure, so Aschwanden turned to scientific and statistical data herself. She concluded that having an annual mammogram starting at age 40 has a 50% chance of resulting in a false-positive result over the next ten years. There is a 6% to 8% chance that a woman will receive a biopsy, and a 1.1% chance that she will be treated for a non-life-threatening cancer. Finally, the chance that a mammogram will detect a dangerous but treatable tumor is only 0.16% for women aged 40 and remains less than 0.5% for women aged 50 and 60.

On the questionable effectiveness of early screening (starting at age 40) They say and experts from the University of Georgia and Georgetown University. They estimate that of the 1,000 women who start regular mammograms at this age and end at age 75, about 600 will at some point have a false-positive result, 70 of them will find out after an unnecessary biopsy, two will be treated for a cancer that would never have killed them, and only one will get results that will lead to needed therapy and therefore significantly prolong her life.

Indicative and calculations Cochrane review 2013. The researchers included data from seven studies involving 600,000 women aged 39 to 74 who either had or did not have mammograms. It found that for every 2,000 women screened regularly over ten years, only one would avoid death from breast cancer, while ten healthy women would undergo unnecessary treatment and 200 would “experience significant psychological distress... due to false-positive results.”

Finally, the results of the analysis, which were published in 2021 by the US National Bureau of Economic Research, showed: For every 100,000 women getting regular mammograms, the added all-cause mortality rate was seven. In other words, women in this group died more often than the population average. The experts did not indicate the exact reasons, but it can be assumed that among them was unnecessary heavy treatment for cancer, which resulted from overdiagnosis.

Despite all these studies, experts emphasize: mammography is the best way to detect breast cancer at an early stage. At the same time, the clinical director of the British organization Breast Cancer Care, Emma Pennery notes: “For every life saved, three women receive unnecessary treatment.” Dr Sarah Heim from Cancer Research UK says: "72% of breast cancer cases are diagnosed when women themselves notice a lump or other symptoms, so screening is not the only way to identify abnormalities."

Thus, mammography is a safe method for screening breast cancer, and its implementation, contrary to some publications, does not provoke the appearance of tumors. However, most experts agree that it is difficult to call it the gold standard of screening - studies show that, despite its high efficiency, mammography often leads to overdiagnosis. The procedure can give false-positive results, and in other cases does not answer the question of how dangerous the detected tumor is. As a result, many patients experience stress, undergo additional diagnostics and even difficult treatment, which in their situation will not be vital. At the same time, this is not a reason to completely abandon mammography and examinations by specialists - paying attention to your own health will help identify breast cancer at an early stage and begin therapy on time.

Cover image: Osprey PolyClinic