Breast Cancer Screening - The evidence For & Against

El_Dangeroso

There's very little evidence that breast-cancer screening does anything to prevent breast cancer mortality and yet we do that. There's a saying in medicine '50% of what we do doesn't work, we just don't know which 50%'.

I suppose my point is that if someone wishes to go to a homeopath and gets great relief, even cured from what is ailing them (presumably most people go for chronic conditions that have only palliative options in allopathic medicine, I would not recommend it for any sort of acute situation) then what is the harm exactly? Even if it turns out that most of the effect comes from a good chat and a sugar pill, can we the mainstream medical community not learn from that?

ZYX

Temple_Grandin wrote: »

Here you go:

http://www.epicentro.iss.it/1/problemi/tumori/reslet.pdf




.

I know it is off topic but you have mentioned twice now about the poor evidence for breast screening and compared it to homeopathy. To back your assertion you use 10 year old opinion from Cochrane. Later in the same year one of the authors in your publication published a review in Cochrane in which he said
http://www2.cochrane.org/reviews/en/ab001877.html
"Screening is likely to reduce breast cancer mortality. As the effect was lowest in the adequately randomised trials, a reasonable estimate is a 15% reduction"

The main problem the authors had with screening was the effect of overdiagnosis. So they felt that the benefits of early detection were negated by over diagnosis. Screening methods have improved greatly in the last 10 years.

Research published this year
http://www.ncbi.nlm.nih.gov/pubmed/20356942

gives a different picture and concludes:
"The benefit of mammographic screening in terms of lives saved is greater in absolute terms than the harm in terms of overdiagnosis. Between 2 and 2.5 lives are saved for every overdiagnosed case."

El_Dangeroso

ZYX wrote: »

I know it is off topic but you have mentioned twice now about the poor evidence for breast screening and compared it to homeopathy. To back your assertion you use 10 year old opinion from Cochrane. Later in the same year one of the authors in your publication published a review in Cochrane in which he said
http://www2.cochrane.org/reviews/en/ab001877.html
"Screening is likely to reduce breast cancer mortality. As the effect was lowest in the adequately randomised trials, a reasonable estimate is a 15% reduction"

The main problem the authors had with screening was the effect of overdiagnosis. So they felt that the benefits of early detection were negated by over diagnosis. Screening methods have improved greatly in the last 10 years.

Research published this year
http://www.ncbi.nlm.nih.gov/pubmed/20356942

gives a different picture and concludes:
"The benefit of mammographic screening in terms of lives saved is greater in absolute terms than the harm in terms of overdiagnosis. Between 2 and 2.5 lives are saved for every overdiagnosed case."

Both of those trials are based on RCT's. Although useful in certain contexts, they are not necessarily the most appropriate design to answer the question of whether or not screening is effective in the 'real world'.

Even the cochrane review said:

It is thus not clear whether screening does more good than harm.

Here's a case-control study from 2005 showing no reduction in mortality from screening:

http://www.bmj.com/cgi/content/extract/331/7512/309

My point being that the results are all over the place and in my opinion no where near convincing enough to justify the expense and unnecessary distress.

Edited to add: How would overdiagnosis have an effect on mortality either way?

tallaght01

I'm not getting involved in this exchange of out-of-date links to out-of-date-studies that no-one has read, let alone critically appraised, other than to address the breast screening issue.

The most recent cochrane report (and, despite what the internet scientists think, just because it's a cochrane review doesn't make it a higher standard than any other review) is in agreement with most of the wider literature.ie there is a reduction in mortality by using a breast screening programme. This is probably about 15-20% overall. But the scale is uncertain, as the measured outcomes have been breast cancer mortality, but there has been a reduction in breast cancer mortality because of a number of factors, and it's hard to assign a percentage to each therapeutic/preventative prong. Plus the reduction is dependent on age and location, socio-economic status etc, and has to be looked at in the context of background levels in the community.

Just wanted to post so that people don't think there's no benefit to getting a mammogram. The real debate is whether the rate of false positives, and cancers that wouldn't have progressed (like most DCIS diagnoses) are worth the benefit.

Anyway, I'll let you back to yizzer hyperlink tennis......

El_Dangeroso

tallaght01 wrote: »

I'm not getting involved in this exchange of out-of-date links to out-of-date-studies that no-one has read, let alone critically appraised, other than to address the breast screening issue.

The most recent cochrane report (and, despite what the internet scientists think, just because it's a cochrane review doesn't make it a higher standard than any other review) is in agreement with most of the wider literature.ie there is a reduction in mortality by using a breast screening programme. This is probably about 15-20% overall. But the scale is uncertain, as the measured outcomes have been breast cancer mortality, but there has been a reduction in breast cancer mortality because of a number of factors, and it's hard to assign a percentage to each therapeutic/preventative prong. Plus the reduction is dependent on age and location, socio-economic status etc, and has to be looked at in the context of background levels in the community.

Just wanted to post so that people don't think there's no benefit to getting a mammogram. The real debate is whether the rate of false positives, and cancers that wouldn't have progressed (like most DCIS diagnoses) are worth the benefit.

Anyway, I'll let you back to yizzer hyperlink tennis......

Gosh, so much condescension in one post, I hope it's not too dizzy all the way up there looking down on us plebs..:pac:

The evidence is far from as conclusive either way, I would seriously question the benefits of wide-scale breast cancer screening. Never mind the risk of metastasis from those actually with cancer. But don't mind me, I'm just an internet scientist.:D The selective skeptism is a little scary tbh..

Why did I know that someone was going to drag this off topic!

Dr Galen

See what I did there

I created a new thread to house a totally new discussion topic which was part of another thread. Hit upon totally by accident by TempleG, thus thats the OP. An interesting practical discussion I think and something I was chatting to some colleagues about only a few weeks ago.

El_Dangeroso

Oh thanks!

I'm really interested to hear the evidence on both sides of this topic.

Tallaght01, you quoted the figures of 20% reduction in mortality, can I get the source on that? The statistics I've been reading are that you need to screen 1000 women for 10 years to save one life.

From what I've been reading:

Jørgensen KJ, et al. Breast cancer mortality in organised mammography screening in Denmark: comparative study Per-Henrik Zahl, Peter C Gøtzsche BMJ 2010;340:c1241

We were unable to find an effect of the Danish screening programme on breast cancer mortality. The reductions in breast cancer mortality we observed in screened regions were similar or larger in non-screened regions and in age groups younger than that screened. The mortality reduction is therefore more likely to be explained by changes in risk factors and by improved treatment than by screening mammography. Our results are similar to what has been observed in other countries with nationally organised programmes. We believe it is time to question whether screening has delivered the promised effect on breast cancer mortality.

And from: http://www.dailymail.co.uk/health/article-1070547/Does-breast-cancer-screening-harm-good.html (Yes, I know the daily fail, but it's a good, balanced article that details both sides quite well.)

The fact is that the screening programme is not even effective at saving lives. Screening takes place every three years, so it doesn't tend to catch the fast-growing, aggressive cancers, such as high-grade invasive duct carcinoma and inflammatory breast cancer [ the ones especially imperative to treat]. Furthermore, only one in 1,000 women will avoid death from breast cancer over ten years of attending screening. Yes, that one life is of infinite value, but think of the downside for all the anxious misdiagnosed women who suffer.

lonestargirl

Cancer Screening in the United States, 2010. A Review of Current American Cancer Society Guidelines and Issues in Cancer Screening

I found this pdf ineresting, it deals with the evidence around screening for a number of different cancer types including breast.

The ACS is recommending mammograms from age 40 but the US Preventive Services Task Force have updates their guidelines to suggest that routine screening begin only at age 50.

Breast cancer debates are a minefield as it is a very emotive area, the risks vary greatly across the population: age; genetic factors (BRCA); lifestyle factors; ionising radation exposure (eg in Hodgkin's patients).

lynnsback

Is there any sign of breast thermography coming to this country I wonder? It would be nice if women here had a choice of screening tools.

lonestargirl

lynnsback wrote: »

Is there any sign of breast thermography coming to this country I wonder? It would be nice if women here had a choice of screening tools.

Probably not, thermography was big in the 70s and then kinda fell by the wayside after the NCI published a report saying it wasn't as good as other tools. It's had a bit of an upsurge recently but most of the research is in engineering and physics journals and is focussing on the algorithms etc. There is not much clinical evidence to support its use instead of mammography and I could only find one clincal trial, in Taiwan, which appears to be still recruiting (and hasn't been updated in a while so it may have been halted).

Although there are places in the US that offer it neither of the two big cancer centres, MD Anderson in Houston and Sloane Kettering in New York, appear to do so. These two centres are big on new technology and if there was sufficient evidence I'd be sure they would be offering it to their patients.

Vorsprung

lynnsback wrote: »

Is there any sign of breast thermography coming to this country I wonder? It would be nice if women here had a choice of screening tools.

It's been shown to be largely useless, unless you have a big tumour, which is of a size to be fairly obvious on normal clinical examination.

Don't have time to find the literature because I'm heading out to work but Ill have a look later when I'm back later.

Traumadoc

The money spent on breast screening , could be argued if invested in cardiovascular services would possibly save more lives.

Breast cancer for good reason is very emotive, but I agree that the benefits of screening are debatable.

tallaght01

Traumadoc wrote: »

The money spent on breast screening , could be argued if invested in cardiovascular services would possibly save more lives.

Breast cancer for good reason is very emotive, but I agree that the benefits of screening are debatable.

I think it depends what cardiac services you're talking about. 20-35% (35% being optimistic, granted)reduction in breast cancer mortality in women over 50, and 15%+ when women over 40 are included is a good return.

Plus bear in mind that it's not just about number of lives saved, it's about DALYs and QALYs too. I haven't don't the comparative analyses, but I'd imagine most of those cured of breast cancer live a fitter life after treatment than those with cardiac disease that has required intervention to prevent death.

I don't think the life saving potential of breast screening is in doubt. The main problem, to my mind, is that 95% of mammography abnormalities are not cancer, so there's a lot of stress involved while waiting for biopsies. Unfortunately modalities such as MRI have a very high sensitivity, but not great specificity, in the general community, so are unlikely to help the problem.

I think the real debate is over regular breast self examination, which has (as far as I'm aware) not been shown to impact on mortality rates.

Traumadoc

I do not have a link at the moment but I believe more women die of preventable heart disease than do from breast cancer - the demographics may be different in that breast cancer may have a lower age cohort that cardiovascular disease and quality of life etc may also be debatable.

I believe the evidence for screening is better for the over 50s but it still does raise concern among health professionals about allocation of resources.
http://www.abc.net.au/reslib/200909/r431846_2068384.asx

As scientists we should question the value of screening and treatment of diseases eg the value of chemotherapy

Nice program explaining the controversy of PSA.

http://www.abc.net.au/catalyst/stories/2702332.htm

tallaght01

Traumadoc wrote: »

I do not have a link at the moment but I believe more women die of preventable heart disease than do from breast cancer - the demographics may be different in that breast cancer may have a lower age cohort that cardiovascular disease and quality of life etc may also be debatable.

I believe the evidence for screening is better for the over 50s but it still does raise concern among health professionals about allocation of resources.


As scientists we should question the value of screening and treatment of diseases eg the value of chemotherapy

Nice program explaining the controversy of PSA.

http://www.abc.net.au/catalyst/stories/2702332.htm

I think that's it. It's about age and DALYs/QALYs.

It's also about having something to screen for. Cardiovascular screening would be complex, and isn't a "one test" screen. I guess you have to look at the criteria for a good screening programme. Though there's no point in denying that Ireland needs better cardiovascular services.

Screening is definitely more valuable for the over 50s, and increases in usefulness with age, but there's less of a QALY/DALY yield with advancing age.

PSA is a terrible screening test, IMO. So many people with raised levels, with such anxiety. Maybe some of the GPs could shed some light, but I know a lot of GPs in the UK when I was there wouldn't do them.

I remember my dad had a slightly raised PSA, and it just caused worry.

thermalbob

lonestargirl wrote: »

Probably not, thermography was big in the 70s and then kinda fell by the wayside after the NCI published a report saying it wasn't as good as other tools. It's had a bit of an upsurge recently but most of the research is in engineering and physics journals and is focussing on the algorithms etc. There is not much clinical evidence to support its use instead of mammography and I could only find one clincal trial, in Taiwan, which appears to be still recruiting (and hasn't been updated in a while so it may have been halted).

Although there are places in the US that offer it neither of the two big cancer centres, MD Anderson in Houston and Sloane Kettering in New York, appear to do so. These two centres are big on new technology and if there was sufficient evidence I'd be sure they would be offering it to their patients.

I am an industrial thermographer. I am posting here as I have had a massive number of calls from women deperate to have this done over the last year or two.

To my knowledge there was a cllinic here in Naas, but it closed a few years ago.

Thermography got a VERY bad name for the detection of breast cancer in the 1970's. This was mainly due to the number of unqualified people doing it. Doctors today are very quick to dismiss it.

It should fit into a proper approach to diagnosis today, but it is not intended to replace the mamogram. Thermography can work well on higher risk patients as it can be done more frequently than the mamogram, so it could be done between mamograms. However it should be done in the same manner as other methods ie refered by a doctor, and as part of a total approach. As it stands, women can go direct to a clinic in the UK, they bring the pictures back to their doctor, who dismisses them, and then they go looking for doctors that will give them what they believe to be the correct diagnosis. This is the wrong way of doing it. You need to get a medical research project going in conjunction with a medical college, and build up a proper collection of information and data. Then doctors will be more receptive to it.

By the way, I will not do this as I am not qualified.