Women harmed, money wasted: Why breast screening needs a rethink
Update on My Practice:
I am still doing mainly telephone appointments, but have relaxed that policy from next week and will see patients face-to -face for those who would prefer to actually see me. Otherwise, the system is working well.
The issue below is one I have discussed many times, and is something i feel strongly about this over treatment and over diagnosis. I have given a lot more information on my web-site under breast screening. It is a complex issue, but i believe in transparency and that women should be better informed about all sides of this debate.
Women harmed, money wasted: Why breast screening needs a rethink
If Australia’s breast cancer screening program was proposed today as a necessary intervention to protect women from the physical and emotional ravages of a disease that kills 3000 a year, would it be dismissed for the harms it causes and the costs it imposes?
Professor Alexandra Barratt.
Put another way is it still worthwhile, fit-for-purpose?
Last month, researchers from Cancer Council NSW published the results of some rough calculations attempting to identify the current price of each single extra life-year generated.
Their estimate was around $65,000. In terms of cost-benefit calculations in healthcare this is very high, higher than the $30,000-$50,000 threshold Australian governments apply when deciding whether interventions are worthwhile.
Such figures are an abstraction, but they suggest something is going wrong because the figures are a result of that clinical issue rumbling for the past 20 years about mass mammography screening driving unnecessary care and significant harms.
“This is a very heated argument around the world. There’s still a live question as to the extent to which it helps women, lengthens life or improves quality of life,” says Professor Alexandra Barratt, a professor of public health at Sydney University.
“The good news has always been that we have reduced breast cancer mortality — but we still don’t know how much of that is a result of new treatments and how much is due to screening.”
She says unlike HPV, the natural history of breast cancer remains something of a riddle.
“With cervical cancer, we know how it progresses, when to screen and when to intervene. We haven’t got that level of understanding with breast cancer.
“One woman said to me she wishes she had never been screened. She doesn’t know whether the treatment matters, whether she may be in the 20% for whom the cancer doesn’t progress.
“However, she feels uncertain about whether she’s done the right thing and angry at not being better informed before.”
Professor Barratt believes around 20% of all screen-detected cancers are overdiagnosed. A review in 2012 in Europe put that figure as low as 1-10%.1
But then within a year a Cochrane review of seven trials involving 600,000 women aged 39-74 randomly assigned to receive screening mammograms or not concluded the rate of overdiagnosis was 30%.2
This means that for every 2000 women screened over 10 years, one will avoid dying of breast cancer, 10 healthy women will be treated unnecessarily and more than 200 women will experience anxiety and uncertainty for years because of false-positive findings.
The point now is that a wave of recent cost-effectiveness calculations on breast screening are including the consequences of overdiagnosis and that, according to Professor Barratt, “makes a huge difference” to whether breast screening appears worthwhile in terms of its financial cost.
The researchers from Cancer Council NSW are calling for Australia to conduct its own formal cost-benefit analysis of the program, which screens some 1.7 million women a year. They note that the last analysis was completed in 2009.
Professor Barratt says in 2013, the Swiss Medical Board conducted its own review and recommended phasing out routine screening, determining that no new systematic program should be introduced.3
Another review in 2013 in the UK made a “best estimate” that annually, 1300 breast cancer deaths are averted through its screening program — “a most welcome benefit.” However, it called for greater efforts to communicate the benefits and harms.4
The result is that today, detailed pamphlets are given to women each and every time they are invited to screen. Professor Barratt says if she could make one change overnight to Australia’s program, she’d do the same here.
“There’s no downside to better informing women, only a small cost.”
But all the number crunching is probably a side issue.
The accountancy headaches will be soothed simply through better targeted screening, where high- and low-risk women are offered different screening intervals and protocols as determined by their individual risk profile, based on genetic mutations, ethnicity, age, breast density and positive family history.
But we still need evidence to quantify what the risks are and it seems we are still only just at the beginning of a process to do that through the large scale randomised trials needed to provide robust answers.
There are two main contenders.
Video: Watch researchers behind the study discuss their hopes for the project.
The US is currently running its WISDOM study, involving 100,000 women.
This trial promises to ‘break the deadlock’ in a debate that has raged and boiled within the medical profession despite being rooted in trial data generated over 30 years ago at a time before personalised medicine was widely embraced, much talked about or even possible.
Under the WISDOM trial, women in the risked-based arm will be divided into four separate risk groups — high to low — and then compared with women offered annual screening (see box below for how women will be stratified by risk).
The researchers say the primary outcomes will be the number of stage IIb or higher cancers using personalised versus annual screening.
They will also be able to compare the morbidity of personalized vs annual screening based on the number of biopsy being performed
The other option began last year — a European trial called My Personalised Breast Screening (MyPeBS).
Some 85,000 women will be randomly assigned to either continue with standard screening while another group will be differentially screened for four years before returning to standard screening.
Like the WISDOM trial they will stratify their individual risk of developing breast cancer.
This study is due to end in 2025.
Professor Barratt is optimistic about what will emerge but she stresses “risk stratification is a big step from where we are at the moment”.
It will also bring with it that the vexed question of how easy it will be to scale back the reach of Australia’s program given the stubborn belief among the public that screening in any form can only be a good thing.
What would happen if a woman deemed low risk is suddenly placed outside the program and loses her life to breast cancer?
It’s the PSA debate again. As with that debate, being told of the costs and benefits doesn’t lessen the anguish of hindsight for a patient and their family when things don’t turn out well
But at least now, while it is going to take time, there is push to make mammogram screening work better beyond the arguments over its rights and wrongs.
|WISDOM US risk stratification and screening recommendations|
|Risk||Risk factors||Screening recommendations|
|Highest risk||BRCA1/2, TP53, PTEN, STK11, CDH1 mutation carrier (or) ATM, PALB2, or CHEK2 mutation carrier with positive family history of breast cancer (or) Women with a five-year risk of 6% or more (risk of an average BRCA carrier) (or) Women with a history of mantle radiation between ages 10 and 30||Annual mammogram + MRI|
|Elevated risk||Women aged 40-49 with extremely dense breasts (or) Women with a five-year risk of 0.75% or more of developing ER-breast cancer based on susceptibility, age, and ethnicity (or) Women in top 2.5th percentile of risk by one-year age category (or) ATM, PALB2 or CHEK2 mutation carrier without a positive family history of breast cancer||Annual mammogram|
|Average risk||Women aged 50-74 (or) Women aged 40-49 with a five-year risk of more than 1.3% or more (risk of an average 50 year-old woman)||Biennial mammogram|
|Lowest risk||Women aged 40-49 with a more than 1.3% five-year risk of developing breast cancer||No screening until age 50|
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