Delete thread please!

securityguy

Pixiechic wrote: »

It worries me when some women don't go and have a smear done. I just don't understand why not really.

The problem with mass screening of asymptomatic populations is that the false positive rate is non-zero. Either the screening shows up a problem which isn't there, or shows up a problem which is there but won't develop any further.

The worst case is PSA screening for prostate cancer; it has a high rate of false positives, most men with prostate cancer will die of something else first and the consequences of operating can be quite serious (impotence and incontinence). The best available evidence (a Cochrane Review) says that mass screening is not beneficial. Men with symptoms should immediately see a doctor, but screening those without symptoms will do more harm than good. The NHS isn't calling men in for screening, and I (a man of about fifty) would decline it, as I have already declined cholesterol
screening.

The same argument might apply to breast cancer screening in older women, and the debate is currently raging. A lot of cancers detected in otherwise asymptomatic post-menopausal women are won't develop further in the rest of the woman's lifetime. Treatment is therefore all risk, for no benefit. The problem is that you don't know whose cancers will develop further, "Watchful waiting" is a hard strategy to explain, and for those women whose cancers do develop, the eventual treatment may need to be more radical. In this case, it's worth quoting the Cochrane summary in full (my emphasis):

Screening with mammography uses X-ray to try to find breast cancer before a lump can be felt. The goal is to treat cancer early, when a cure is more likely. The review includes seven trials that involved 600,000 women who were randomly assigned to receive screening mammograms or not. The review found that screening for breast cancer likely reduces breast cancer mortality, but the magnitude of the effect is uncertain. Screening will also result in some women getting a cancer diagnosis even though their cancer would not have led to death or sickness. Currently, it is not possible to tell which women these are, and they are therefore likely to have breasts or lumps removed and to receive radiotherapy unnecessarily. The review estimated that screening leads to a reduction in breast cancer mortality of 15% and to 30% overdiagnosis and overtreatment. This means that for every 2000 women invited for screening throughout 10 years, one will have her life prolonged. In addition, 10 healthy women, who would not have been diagnosed if there had not been screening, will be diagnosed as breast cancer patients and will be treated unnecessarily. Furthermore, more than 200 women will experience important psychological distress for many months because of false positive findings.

It is thus not clear whether screening does more good than harm. Women invited to screening should be fully informed of both the benefits and harms. To help ensure that the requirements for informed consent for women contemplating whether or not to attend a screening program can be met, we have written an evidence-based leaflet for lay people that is available in several languages on https://www.cochrane.dk.

Cervical cancer screening looks better that PSA or mammography, although the numbers needed to treat are very large (you have to screen a lot of women for a long time to save lives). However, it would not now be ethical to do a prospective trial of cervical cancer screening, and the published trials are all a long time ago, when rates of smoking were much higher. That makes doing a modern review of evidence very difficult. If you could do such a trial, it is a matter of some speculation what the outcome would be, but it's likely that it would prove to be a small number of lives saved in exchange for performing a lot of unnecessary surgery, and you can't perform a lot of surgery without there being some level of deaths.

This article is worth reading:

http://www.independent.co.uk/life-style/health-and-families/features/why-im-saying-no-to-a-smear-7577967.html

as is this followup to it

http://www.margaretmccartney.com/blog/?p=1366

claire16c

bumbledore wrote: »

Look the evidence is out there don't just rely on the leaflet you should make informed consent.

Other countries don't start screening till 30, some 25 Scotland starts at 20 when the risk to this age group is low and showing of abnormal results doesn't mean cancer causing needless stress and anxiety and possibly over treatment.

Smear testing on a whole isn't that effective only a small amount of women are saved through such a screening.

You have made your choice to have smear tests at your age so please respect mine to not have them at this stage in my life.

In other countries they start at 16 or 18 or when you start having sex.

So a small number of lives isn't important to you? I don't need to respect anyone's choice.

I put off my test until I was over 25 and think I was stupid to do so.

Robisere

Just speaking as a dad and a long-married bloke here.
Many of the replies and counter-arguments here, seem very "catty" to me.

Now, I do not agree with the OP's conclusion about not going for the test, but that is surely her own decision. I question why she has to advertise her decision here, as all it appears to have achieved is to set people against each other. Please calm down, ladies!

I know that my own dearly-loved daughter (now in her 40's, still as gorgeous as her mum) has regularly attended these tests, as she does for the breast cancer tests. I would be trying hard to change her mind, if she had decided not to go at any time. In fact, some years ago, DD was found to have a small problem in that department, which would have got much worse if not spotted. I cannot think of life without my DD, she is and always has been a shining light to me.

That's a dad's point of view, OP - do you have a dad? Talk it over with your parents, they would be distraught if anything happened to you.

securityguy

claire16c wrote: »

You could be at a very low risk for getting something and still get it!

I don't understand why you wouldn't want to get a test done.

Suppose you have a test which is 99% accurate. Very few tests are remotely that accurate, so the rest of my numbers are generous to testing. Suppose that you have a 1 in a 1000 chance of having a particular condition on the day you have the test. That is, in round numbers, the chance per year of having a cancer for which you don't have other risk factors.

You have the test. It is positive.

What is the chance that you have the disease in question?

Well, for every 100 000 people like you tested, 100 have the disease. 99 of them will be correctly diagnosed. One of them will be given a false "all clear". 99 900 don't have the disease. 999 of them will receive a false diagnosis. So in 100 000 people, 1098 will receive a positive diagnosis, but only 99 of them have it.

In real tests, the sensitivity (the rate at which people who definitely have the condition are correctly detected) and the specificity (the rate at which people who definitely don't have the condition are correctly excluded) aren't necessarily the same, which complicates the calculation. But that doesn't affect the basic thrust. Consider a 90% reliable test for a 1 in 1000 condition: you have a nearly one in ten chance of being told you have it, but a just less than one in a thousand chance you actually do. So a positive test is wrong nearly 99% of the time. Which is fine, so long as the next stage of the investigation, or indeed treatment, is harmless. It rarely is.

(Edited to incorporate LannieDuck's clarifications)

Person_one

Robisere wrote: »

Just speaking as a dad and a long-married bloke here.
Many of the replies and counter-arguments here, seem very "catty" to me.

Thanks for the Mansplain, always a joy.

Person_one

fluffymuffy wrote: »

My own experience is that cervical screening IS in practical effect compulsory. I was literally held by the wrist at the doctor's reception desk (by the receptionist - who was the doctor's wife) and effectively told that if I didn't attend screening there was to be some doubt as to my ability to be responsible for my children.

That's absolutely bonkers and I don't believe it for a minute.

However, if you are 100% positive that you don't want to be screened for a potentially fatal illness, why would letters bother you? Are they those Harry Potter letters that scream at you? Are they Mission Impossible style letters that self destruct and make a mess of the kitchen table?

I get far more emails from nigerian princes after my bank details than I do screening invitations from the NHS, but I'm not interested in their offer so I just ignore them. I suggest you do the same!

LannieDuck

securityguy wrote: »

Consider a 90% reliable test for a 1 in 1000 condition: you have a nearly one in ten chance of being told you have it, but only a one in a thousand chance you actually do. So the test is wrong 99% of the time. Which is fine, so long as the next stage of the investigation, or indeed treatment, is harmless. It rarely is.

It's not wrong 99% of the time. It's wrong 10% of the time.

Given 10,000 people, your scenario will include 10 actual cases of actual cancer.

90% of the diagnoses will be correct:
* 9 cases will be correctly identified
* 8,991 people will be correctly cleared

10% of the diagnoses will be incorrect:
* 1 actual cases will be missed
* 999 people will be told they have cancer when they don't

The question is whether it's worth misdiagnosing 999 people in order to properly diagnose 9/10 cases of cancer. As you say, it depends on what the next step is.

mum2one

geri1965 wrote: »

A woman in Bristol died from cervical cancer recently as she was too young for a routine test and they refused to give her one when asked.

I loathe smear tests - I find them utterly repugnant, but I'm pretty sure the treatment for cancer would be worse.

I dont like smear tests but for 30 seconds of embarrasement - which to is what is - could be a life saver.

I use to avoid smear tests - but then a friend moaned like hell at me so I went, it was lucky as I had pre-cancerous cells - I had to have treatment I was 29 yrs old - I thought this happened to people in their late 30s/40s I never thought it would be me.

Now I'm 42, I'm on yearly recalls and I still dont like them, but I have a daughter that needs her mum and I love life.......... x

securityguy

LannieDuck wrote: »

It's not wrong 99% of the time. It's wrong 10% of the time.

Slippery stuff, language. I meant that of every 100 positive results, 99 of them are false positives. You meant that of every 100 tests, 10 of them give the wrong answer. They're equivalent, I think. My point is that what sounds like a good number ("90% reliable") is distinctly less good when it comes to "given a positive test result, what is the chance that I have the condition". They come down to the same question, as you say:

The question is whether it's worth misdiagnosing 999 people in order to properly diagnose 9/10 cases of cancer.

And that's the informed consent issue.

The case in Bristol (which prompted a marvellously point-missing piece from Babs Ellen in the Observer yesterday) is completely different. There, a woman under 25 turned up at the surgery with clear symptoms that required investigation, and a GP (whom I suspect is now busy checking their MDU subscription is up to date) refused to do anything as she was too young.

That's not "should doctors do screening on asymptomatic women under 25?", where the evidence is on balance "no". That's "should doctors do diagnostic investigations for symptomatic women?", where the answer is obviously "yes, right now, yesterday if possible". Routine screening may or may not have helped (an aggressive cancer can develop between screenings) but a doctor doing their job properly almost certainly would have.

The problem with screening is that in the absence of other symptoms, the false positive rate may be too high for comfort. But when there are other symptoms, the situation is completely different. Someone who is positive for a screening test and has the symptoms of the condition is far, far less likely to be a false positive.

LannieDuck

securityguy wrote: »

Slippery stuff, language. I meant that of every 100 positive results, 99 of them are false positives.

Ahh, my apologies.