July 1, 2024
The new Canadian recommendations
We talked about the new breast cancer screening recommendations published very recently by the CanTaskForce group, here: https://cancer-rose.fr/2024/05/30/actualisation-des-recommandations-canadiennes-sur-le-depsitage/
These new Canadian recommendations are much more measured and cautious than the latest U.S. recommendations of May 2023, which have been the subject of considerable debate and controversy, since they advocate starting screening as early as age 40, even though there is no new scientific data to justify this, and no evidence of the relevance of starting earlier in view of the disadvantages and risks of mammographic screening for these young populations. (https://cancer-rose.fr/en/2023/09/17/lowering-the-age-of-screening-a-pandoras-box/
And https://cancer-rose.fr/en/2023/05/16/lowering-the-age-for-starting-screening-but-at-what-cost/)
The new draft guidelines on breast cancer screening published by the Canadian Task Force on Preventive Health Care on May 30, 2024 were therefore eagerly awaited. Intense pressure was exerted by screening promoters, in the media, by the Canadian Minister of Health himself, to demand a screening recommendation for women in their forties.
The independent Canadian working group resisted the pressure, after a colossal task of analyzing over 165 studies, including observational studies, randomized controlled trials and mathematical modeling trials, as well as Canadian statistical data and screening programs.
The new Canadian recommendations are as follows
- – For women aged 40 to 49, based on current evidence (trials, observational studies, modeling and a review of values and preferences), we suggest against routine mammography screening. Given that individual values and preferences may vary, people who wish to be screened after being informed of the benefits and harms should be offered screening every two or three years (conditional recommendation, data of very low certainty).
- – For women aged 50 to 74, based on current evidence (trials, observational studies, modelling and a review of values and preferences), we suggest mammography screening every two to three years. As individual values and preferences may vary, it is important that women aged 50 to 74 are informed of the benefits and harms of screening when making their decision.
- (conditional recommendation, data of very low certainty).
- – For women aged 75 and over, based on current data (observational studies and modelling; no trials available), we suggest no mammography screening (conditional recommendation, data of very low certainty).
As we can see, each recommendation is conditional, linked to the fact that women have received adequate information. It is striking to note that for each recommendation, the evidence is classified as being of very low certainty, because for the members of the Canadian group, after analyses of all the above-mentioned available material, the certainty concerning the benefit of screening is evaluated as low or even very low, particularly as regards the gain in mortality, which is judged to be very fragile.
Advocates of earlier screening point to early detection as a means of reducing the incidence of the most advanced cancers, but the working group found, by comparing screened women with those who were not screened, that there was no significant difference in the number of cancers diagnosed at stage 2 or at a more advanced stage between the two groups, i.e. early detection does not reduce the incidence of cancers at more advanced stages.
This is explained by the natural history of cancer, detailed here,
The good news for women is that annual breast cancer mortality has fallen steadily, for screened women AND for unscreened women.
Reactions
Scientists from the University of Sydney
Karsten Jorgensen (Cochrane Denmark, University of Southern Denmark, Odense, Denmark) praised the Task Force on twitter for its “emphasis on informed choice and lack of direct recommendation for or against screening”.
Reaction from Rethink Breast Cancer
Rethink Breast Cancer is a Canadian non-profit organization that defines itself as “known for bringing positive change and rethinking the status quo when it comes to breast cancer. Rethink educates, empowers and advocates for system change to improve the experience and outcomes of those affected by breast cancer, focusing on historically underserved groups: those diagnosed at younger ages, those with metastatic breast cancer and those systematically marginalized due to race, income or other factors. We’re elevating, inspiring and, most importantly, rethinking breast cancer to help people live better, longer lives.”
Here is a text from its founder, Madame De Coteau, which we summarize below with a few extracts- https://rethinkbreastcancer.com/articles/on-breast-screening
Ms. De Coteau is reacting to the very strong and angry reactions of Canadian screening promoters who advocate starting screening as early as age 40, against the new recommendations just issued by the Canadian CanTaskForce working group, which do not recommend such early screening.
The CanTaskForce group’s recommendations are cautious, based on evidence and existing literature, and take into account the benefit-risk balance of screening for different age groups. They do not recommend screening before the age of 50, due to the unfavorable benefit-risk balance for younger age groups.
Ms. De Coteau writes:
“The dialogue on breast cancer screening has once again intensified with anger at the Canadian Task Force on Preventive Health Care and its draft guidelines on breast cancer screening for people at average or moderately high risk.”
De Coteau explains why the ReThink Breast Cancer Foundation will not participate in this promotion and will not take advantage of “clickbait media stories, confusion about screening versus diagnostic mammograms, and the fear and emotion that anyone affected by breast cancer lives and breathes.
We could easily capitalize on this momentum, increase our influence on social media, boost fundraising and try to bank on promotion, but we won’t. It’s not in line with our values.”
Further on she adds: “We are committed to helping historically underserved breast cancer patients whose needs are not being met by a single approach.
We are committed to ensuring that those most at risk of breast cancer are prioritized for early and comprehensive screening.”
….
“We want every breast cancer to be detected and treated early, and for outcomes to continue to improve.
But if there’s one thing we’ve seen from working in the field for over 20 years to improve outcomes for historically underserved breast cancer patients, it’s that one size doesn’t fit all. We’ve seen huge improvements in outcomes as treatments have become targeted, and we need a similar way of thinking about screening and detection.
Population-based breast cancer screening is important, but mammography screening programs have had a more modest impact on breast cancer outcomes than most people realize. The impact is modest relative to the cost, which is why its effectiveness as a health intervention has been so widely debated since its introduction.”
…
The current focus on expanding our breast cancer screening programs by age overshadows the issues of young people with breast cancer, the metastatic breast cancer community and other historically underserved groups including those who are racialized, immigrant or affected by other social determinants of health.”
Thus, in her view, the debate over the age of screening in the general population overshadows the real causes of severe breast cancer in certain population groups, in whom the real causes must be sought.
“What we know from our experience,” she says, ”is that the popular narrative about breast cancer screening lacks nuances that are very important to understanding the whole story of breast cancer. The best age to start mammography screening for average-risk women has been debated since the 1980s. That’s many years. And I feel like I’ve been working on this part for years.”
For this reason, Ms. De Coteau reminds us of key points that are the reality of screening and that underline the need for caution in recommendations and nuances to be made, and why earlier screening for everyone is not justified:
– The decline in breast cancer mortality in the U.S. has been similar (and mortality sometimes even lower) in other high-income European countries where screening of the average-risk population only begins at age 50.
– Black women in the U.S., where screening programs begin at age 40, have poorer outcomes for breast cancer. Is this a problem of access to screening? Biological reasons? A bit of both? Black women have higher rates of triple-negative breast cancer, which is more aggressive with a subtype more likely to appear between screenings.
– At present, there are no effective tools for screening average-risk women under 40. Younger women tend to have dense, opaque breast tissue on mammography, which masks the visualization of potentially cancerous lesions.
– More women under 40 are being diagnosed, which is extremely worrying, but it’s a problem that needs to be tackled. But it won’t be solved by population-based screening.
– Mammography screening programs detect the earliest stage breast cancers, which are also the easiest to treat.
– Screening programs are not effective in detecting aggressive, fast-growing tumors, which are those diagnosed in many young people and are more likely to metastasize before they are only seen on mammography.
– Screening mammograms, even in combination with ultrasound, can miss up to 20% of malignant tumors. This type of high error rate would be unacceptable in many other areas of medicine and research. Given that breast cancer rates are rising in young women, and that metastases are largely incurable, this false-negative rate is worrying, but receives little attention.
Ms. De Coteau refers to U.S. recommendations, which call for earlier screening because racial inequalities mean that black women have more cancers at younger ages. However, these recommendations are not based on any scientific argument, they are made on the basis of models, but are likely to miss the real causes, which are, for black American women, poorer access to healthcare and more unfavorable living conditions.
She writes: “Last month, the United States Preventive Services Task Force (USPSTF) changed its recommendation for average-risk women to receive a screening mammogram every two years starting at age 40 (their recommendation for the starting age of screening for average-risk women has changed from 40 to 50 to 40 over the past two decades). We saw what Dr. Laura Esserman, an internationally renowned breast surgeon and breast oncology specialist, shared on X ( former twitter): “The USPSTF guidelines have changed yet again, and no new leads have prompted this change. The same data are analyzed and reanalyzed. It is not possible to personalize risk-based screening for specific tumor types or to personalize prevention recommendations. We need new trials and new data instead of rehashing the same data.””
…
“As evidenced by the various announcements here in Canada,” De Coteau explains, ”there is momentum toward reducing the age of breast cancer screening for average-risk individuals. False negatives aside, this will undoubtedly lead to more false positives, more unnecessary biopsies and sometimes even over-treatment. Although people are quick to declare that they’re not bothered by this, we worry about the unintended negative consequences for the breast cancer community. Resources aren’t infinite, and this change could lead to delays in screening those at higher risk for breast cancer, including slowing access for high-risk individuals in underserved communities.
In addition, the accumulation of false positives in our system can slow access to urgent mammograms and diagnostic biopsies, delaying access to treatment. Earlier this year, we were shocked and extremely concerned by the case of Lindsay Rogers in Saskatchewan, who waited months for a diagnostic mammogram after finding a lump in her breast due to a shortage of specialized breast radiologists.”
These remarks are also of interest to the European population, at a time when screening mammograms are widely prescribed, often by gynecology specialists at an increasingly early age, despite the more frequent disadvantages in younger women, the absence of any scientific evidence of a benefit in younger women, and also despite the official recommendations in force in our country (screening from the age of 50 and not before).
HAS (Health Authority in France): “The HAS recalls that, in the absence of risk factors for which specific breast cancer screening is recommended, there is no reason to perform a screening mammogram or breast ultrasound outside the age range of participation in the national organized screening program, i.e. between 50 and 74 years of age.”
In order to track down these particular, deadly cancers that affect women of a young age, there may be other ways than inflicting a screening procedure involving risks on an entire population with no particular excess risk, making them incur these risks and inconveniences with serious consequences (overdiagnosis, overtreatment).
Ms. De Coteau:
“When we think of a major investment to save lives from breast cancer, why is reducing the screening age for average-risk people so widely advocated? Are there other investments that could save more lives?
A few weeks ago, a prominent American podcaster in her mid-40s went public with her breast cancer diagnosis. She started mammograms at 40, but last year embarked on a journey to understand her own risks. She discovered a family history…. and learned that her extremely dense breast tissue increased her risk. So she asked for a more comprehensive approach to her annual screening. Recently, she had a 3D mammogram that was completely clear. A week later, her MRI showed something that led to a biopsy, which led to her diagnosis of breast cancer.
… Even high-risk screening programs don’t guarantee that all breast cancers will be detected early.
Last October, I participated in a roundtable discussion with other cancer leaders in Ontario to develop recommendations for Cancer Care Ontario (CCO), which was in the process of developing a renewed five-year cancer plan. At the meeting, a young breast cancer patient shared her older sister’s story, which highlighted the challenge of screening 40-year-olds. Her sister is a young woman in her forties who was participating in a screening program for high-risk women due to her mother’s diagnosis, so she undergoes an annual mammogram and MRI. Although BRCA positive with no known genetic mutations, between her annual screening in a program for high-risk women, she was diagnosed with breast cancer, which had already spread to her lymph nodes.”
“It’s a lot of this type of breast cancer that Rethink sees in younger women – the most aggressive forms with the most aggressive behavior that are diagnosed more frequently in young people. These cancers can appear between screenings, even if you’re screened annually as part of a high-risk screening program.”
Ms. De Coteau asks whether, rather than extending the same program to other ages, a stratified risk approach and screening programs based on people’s risk profile would be more relevant and save more lives.
“What I fear,” she says, ”is that we have reached a point where, even with evidence from trials suggesting that a pragmatic approach would be smarter and more effective, a paradigm shift to precision screening based on risk rather than age is almost impossible.”
She points to the role of the media:
“The way the media has evolved over the past decade means that we have very few experienced health editors, new health data researchers and health journalists working on health in depth, so one-sided stories from press releases are now the norm.”
This is the unfortunate observation we make every year in France during the pink October campaign, with always the same stories and slogans reproduced on news channels, in magazines and on networks, or testimonials and opinions from whatever personalities who know nothing about the subject but are never stingy about telling their own story. Unfortunately, there aren’t many in-depth articles, except for a few specific media, such as Que Choisir Santé, whose articles are based on investigations and real scientific journalism.
Ms. De Coteau concludes by stressing that, in discussions around breast cancer, we are equally compassionate and supportive of breast cancer patients, but that despite this, from the point of view of health equity, we need to keep an eye on unwanted negative impacts and serious consequences for the population that need to be avoided.
As the WHO points out in its screening manual (page 19), we cannot ethically impose a potentially unfavorable health measure on certain classes of the population for the possible benefit of others (all the more so as, in breast cancer screening, the expected benefit of earlier screening for people in their forties has never been demonstrated). “A deontological point of view might state that some things cannot be morally justified whatever their outcome; in short, harmful effects borne by healthy people are not justified even if there is benefit for others.”
Reactions in the BMJ from scientists at the University of Sydney
On June 24, scientists from the University of Sydney took a stand in an editorial in the BMJ, explaining why starting screening at the age of 40, as recommended in the United States, would be more harmful than beneficial. The U.S. recommendations for lowering the age of screening from 50 to 40 have been widely publicized, not on the basis of scientific fact but on the basis of a highly contested modeling study, with the aim of reducing racial inequalities, with black women contracting more cancers with a poor prognosis and dying more from breast cancer. We talked about this in this article.
According to Katy JL Bell, Professor of Public Health at the University of Sydney, and her collaborators, some of whom are members of the Wiser Healthcare Research Collaboration, Australia, this change in guidelines will immediately affect over 20 million American women and other women aged 40 to 49, with repercussions far beyond the USA. In this article, we explain why this issue also concerns us in Europe.
A change of this magnitude, say the Australian authors, should reflect new data from randomized trials or trends in cancer mortality. However, this commissioned expert report makes no mention of any such trials.
The new recommendation appears to be based on two interrelated considerations. The first is recognition of the inequality in breast cancer mortality between black and white American women, and a commitment to reduce this inequality. The second is statistical modeling of a hypothetical population which showed that starting screening at age 40 would reduce breast cancer mortality, particularly among black women.
The contestation is already focused (and shared by many scientists) on the fact that the American task force relies increasingly on modeling rather than empirical evidence. Modeling assumes that the benefit/risk balance of screening is more favorable for all population groups than the evidence from clinical trials, and makes a number of assumptions that may not correspond to reality.
In fact, cancer does not develop according to the imagined model of progressive and ineluctable tumour growth, but according to an unpredictable pattern which means that some cancers develop very quickly and escape detection, while others develop so slowly that they never endanger the life or health of the person concerned, but are detected unnecessarily and treated unnecessarily. This is overdiagnosis, as explained at length here: https://cancer-rose.fr/en/2021/10/23/what-is-overdiagnosis/
The Australian team writes: ‘Racial inequality in breast cancer mortality in the United States has been observed since the widespread adoption of screening mammography (and adjuvant endocrine therapy) in the 1980s. Screening mainly benefits women with hormone receptor (HR)-positive cancers; HR-negative tumours are more aggressive and tend to be diagnosed at later stages, in younger women, and are not detected by screening mammography.
HR negative tumours are more common in black women for hereditary reasons and because of the social determinants of health. Instead of extending mammography screening to younger women, initiatives are needed that address the systemic inequities at the root of racial inequality in breast cancer care, particularly with regard to access to high quality, timely and effective care and treatment.’
Furthermore, ‘None of the included trials showed a significant reduction in breast cancer mortality with screening, including the UK Age trial, the largest (n=160,921) and most recent trial specifically designed to determine the effectiveness of screening in women aged 40.’
There is therefore no significant reduction in mortality and, on the other hand, there are disadvantages which do not make the benefit-risk balance favourable, as listed in the editorial:
– The rates of false-positive mammograms were highest in women aged 40 to 49.
– Rates of additional diagnostic imaging were also highest in the 40-49 age group: 12,490 (10,930 to 14,230) per 100,000 women screened.
-Many women also had to undergo clinical consultations and procedures such as surgical biopsies, which entail significant costs for the healthcare system.
– The negative psychosocial consequences, such as anxiety and the difficulty of finding time for follow-up in a busy life, represent an additional burden for women.
Overdiagnosis is at the heart of the problem, although estimates vary widely: ‘Trial estimates of overdiagnosis (cancers that would never have caused symptoms or death if they had not been detected and treated) vary from 11% to 22% of cancers detected. Most people who are over-diagnosed will also be over-treated with surgery (with or without adjuvant radiotherapy) and hormone therapy.
They will not benefit, but may suffer the consequences: adverse effects from surgery and hormone therapy, and increased risk of coronary heart disease and other cancers after radiotherapy.
Finally, although there are no trial data on the radiation effects of mammography, one modelling report found that there could be seven additional radiation-induced breast cancer deaths per 100,000 women with biennial screening starting at age 40 (12 deaths) rather than age 50 (5 deaths).’
Miglioretti DL, Lange J, van den Broek JJ, et al Radiation-induced breast cancer incidence and mortality from digital mammography screening. Ann Intern Med2016;164:205-14. doi:10.7326/M15-1241 pmid:26756460
Editorial conclusion: “Instead of adopting the new US recommendations, policymakers should work with communities to design initiatives that address the root causes of racial inequality in breast cancer care for black women and other underserved groups.”
Related articles
Absence of benefit from mammograms in women aged 40-50 years confirmed by final results of UK Age Trial
Lowering the age of screening? A Pandora’s Box
Lowering the age for starting screening, but at what cost?
SHOULD 40-YEAR-OLD WOMEN BE SCREENED?
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