Translation and synthesis be Cancer Rose
https://www.sensible-med.com/p/should-women-in-their-40s-be-screened?utm_campaign=post&utm_medium=web
July 1, 2024
Adam Seth Cifu is an American physician, academic, author and researcher. He is Professor of Medicine and Director of Academic Programming at the Bucksbaum Institute for Clinical Excellence at the University of Chicago. He is an editor for the online media Sensible Medicine.
Sensible Medicine is a reader-supported publication. On June 18, 2024, Sensible Medicine published a commentary by K. Jorgensen on breast cancer screening of 40-year-olds women, since there is a controversy on this subject, with US guidelines recommending screening as early as age 40, whereas Canadian guidelines do not.
Karsten Juhl Jørgensen (MD, DMedSci) is Professor in the Department of Clinical Research at Københavns Universitet, Cochrane Denmark. He has studied the impact of screening over the past 20 years.
Karsten Jorgensen’s point of view
A few weeks before the Canadian Task Force on Preventive Health Care (CTFPHC) published their draft recommendations on breast cancer screening, an article was published about a study on the incidence of breast cancer in young Canadian women. A disturbing increase of “up to 45.5%” was observed, particularly among women in their twenties.
Sounds frightening, doesn’t it?
Two weeks earlier, the USPSTF (Preventive Services Task Force) published updated guidelines on mammography. In a major reversal, members now recommend mammography screening for women in their forties. Previously, they recommended informed choice for this age group.
They, too, have observed an increase in breast cancer incidence in young women, and this was one of the three reasons they changed (their recommendations), the other two being new calculation models, and concern over the fact that young black women have a risk of dying from breast cancer some 50% higher than other groups.
Yet the Canadian Task Force (CTFPHC) draft guidelines did not recommend that 40-year-old women be screened. What’s all this about?
The evidence for breast cancer screening is aging. Most trials date back to the 1970s and 1980s. Since then, there have been major changes in our understanding of the biology of breast cancer, and how it is diagnosed and treated.
Fortunately, there is less stigma associated with a breast cancer diagnosis today, and more women are seeking help earlier if symptoms arise. Surgeons have discovered that more radical treatment is not always better, reducing the damage associated with surgery. Radiotherapy has also improved and is more targeted with lower doses, also reducing harm.
But perhaps most importantly, adjuvant therapies such as tamoxifen and aromatase inhibitors (anti-estrogens) have been incorporated into care since the 1990s.
These advances have collectively led to one of modern medicine’s greatest successes. Over the past 30 years, women under 50 have seen their risk of death from breast cancer halved. A truly remarkable achievement, especially in such a young age group with so many precious years ahead.
We can say, definitively, that screening did not play a major role in this success. Because the reductions (in the risk of dying), if any difference exists, have been greater in countries that do not screen women in their forties.
The clinicians who treat breast cancer and the researchers who devote their careers to improving breast cancer treatments deserve far more credit than they receive.
There is a clear age gradient in the reductions (in the risk of death) seen internationally, with the youngest age groups seeing the greatest improvements, the smallest reductions seen in the most commonly screened age groups (50 to 74), and the lowest reductions among older women (Figure 1). This gradient is consistent with improvements in treatment, not with screening as the cornerstone of modern healthcare.
The fact that screening does not play as important a role as we have been told for decades may seem paradoxical. We know that breast cancers detected at an advanced stage have a much worse prognosis than those detected at an early stage.
But to think that the cancer we detect late would have the same prognosis as those we detect early, if only screening had “detected it earlier”, is an oversimplification.
It is based on the assumption that all breast cancers represent the same disease at different stages of development. This assumption is at odds with modern understanding of cancer biology. (read here)
The biology of cancer is complex. We’re dealing with a range of diseases of varying gravity. Those we detect late because of symptoms more often have an intrinsically aggressive biology and develop rapidly, spread early and are resistant to treatment.
They are therefore selectively those with a poor prognosis, and their biology is determined very early on.
Detecting such tumors a little earlier is unlikely to change their prognosis, as screening cannot change their biology.
Breast cancer exists in an ongoing battle with the immune system, and many cancers are eliminated.
Read here-
Unfortunately, the growth rate of many cancers is faster at younger ages, including breast cancer. This means that screening at regular intervals is unlikely to catch them. Denser breast tissue in younger women also means that mammograms are less likely to find cancers.
Model calculations, such as those underlying the USPSTF’s modified recommendation, are based on presumed benefits (of screening). But, collectively, the least biased trials of breast cancer screening have shown no benefit for this age group (see UK Age trial data).
While this does not exclude the possibility that a small benefit may exist, the USPSTF recommendation does not meet the criteria of evidence-based practice, and the step back from official screening criteria is deeply worrying. (Read this)
But what about the growing incidence of breast cancer in young women? Surely a reason to worry, and to increase screening?
Again, things are more complicated than we might think. The USPSTF and CTFPHC recognize, and quantify, the most significant harm of breast cancer screening, which is overdiagnosis.
Overdiagnosis is when screening finds a lesion that fits the pathological criteria for cancer, but grows so slowly (if at all), that the person with that cancer would never have been diagnosed and would not have died of the disease without screening. Why is this important? Imagine the fear, the impact on quality of life and the physical consequences of a cancer diagnosis and treatment. And imagine that everything this person and their family went through was for nothing. We don’t know how many go through this, but qualified estimates are about 3 overdiagnosed for every woman screened.
Over-diagnosis occurs less often in younger women, and more often because of so-called “precursor” lesions (ductal carcinoma in situ). But there is a real possibility that the observed increases in incidence are partly iatrogenic, i.e. caused by doctors and increased diagnostic activity.
Neither the USPSTF nor the media mention this possibility, but to achieve a 45.5% increase in the number of women affected in their twenties requires very few additional breast cancers because, fortunately, breast cancer remains extremely rare in this age group. (Editor’s note: Because breast cancer is rare in the twenties, a very small number of additional new cases automatically raises the incidence rate sharply, more abruptly than if the prime rate were higher).
For women aged 20 to 24, the risk of dying from breast cancer is literally one in a million (Figure 2).
The increase (in incidence) was only 9.1% for women in their forties.
Even before the new USPSTF recommendations, 85% of black women compared with 78% of other women had been screened in the last 2 years.
The fact that more black women are already being screened flies in the face of the idea that recommending more screening for all groups will solve the very serious problem of higher breast cancer mortality within one group.
On the contrary, recommending screening for all young women is likely to exacerbate the rising incidence rather than reduce it.
Ensuring that everyone has access to optimal treatment is more likely to reduce the worrying health disparity.
Although it may seem as though we are in the midst of a cancer crisis, the mortality data reveal a very different and positive reality: we are living through a triumph of modern medicine and there are fewer reasons to start screening women in their forties today than ever before.(Read here)
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