Saturday, April 21, 2007

HRT now linked to ovarian cancer!

The drumbeat of the anti-HRT war grows louder. Yesterday HRT was accused of causing breast cancer. Today it is accused of causing ovarian cancer -- on equally frivolous grounds. A PDF of the full journal article in "Lancet" is here. I reproduce a media report of it below. Rather than adding to my own comments of yesterday, I follow the media report with a reproduction of Prof. Brignell's comment on the nonsense. Prof. Brignell is a mathematician who campaigns against the ignorant and malicious misuse of statistics

HORMONE replacement therapy, a contested treatment for post-menopausal women that has already been linked to breast cancer, is also associated with ovarian cancer, a study in The Lancet said today.

Women who take HRT are on average 20 per cent likelier to develop and die from ovarian cancer compared to women who have never been on this treatment, according to the research. The evidence comes from a major British investigation into female health, the Million Women Study, covering 1.3 million British women from 1996-2001.

HRT entails taking substitutes for oestrogen or progesterone after natural levels of these key female hormones diminish after menopause. The idea behind it is to reduce symptoms such as hot flushes and vaginal dryness and boost protection against osteoporosis and heart disease.

The British researchers assessed data from 948,000 post-menopausal women, who had been questioned and later given a follow-up exam some three years later. Around 30 per cent were current HRT users; 20 per cent had previously received HRT; and the remaining 50 per cent had never taken it. Across all three groups, a total of 2273 women developed cancer, and 1591 died from it.

The increased risk of cancer, though, was shouldered by current HRT users, especially those who had been taking the hormones for at least five years. The risk was largely unchanged by such factors as a smoking habit or past use of oral contraceptives. Women who had stopped HRT had the same risk level as counterparts who had never taken the treatment.

In a commentary, Steven Narod of the Women's College Research Institute in Toronto, Canada, said the relative risk of 20 per cent might be thought of as small, "but enormous numbers of women have been exposed." In the Million Women Study alone, nearly 500,000 had taken HRT, he pointed out. Extrapolated across the British population, around 1000 extra women died from ovarian cancer between 1991 and 2005 because of HRT.

The HRT link with breast cancer surfaced in 2002 [See my post of 14th. for a comment on THAT crap study], prompting many women in the US to drop the treatment - a trend that notably coincided with a sharp fall in new breast cancer cases in the US. The authors of the new study are led by Valerie Beral of the Cancer Research UK Epidemiology Unit in Oxford, Britain. The paper appears in next Saturday's issue of The Lancet. Beral says HRT's effect should be seen in the context of breast and endometrial (uterine wall) cancer, as well as ovarian cancers. These three types of tumour account for 40 per cent of all cancers diagnosed in British women. "The total incidence of these three cancers in the (Million Women Study) population is 63 per cent higher in current users of HRT than never-users," the study notes.


The empire strikes back

By John Brignell

Like the environmentalists, the epidemiologists do not like to have their hegemony over their corner of the media to be challenged. No sooner has their dangerous and destructive nonsense over breast cancer been thwarted than they come out with even more dangerous and destructive nonsense about ovarian cancer. Valerie Beral, a women noted for the size of her Trojan Numbers, has come out with a relative risk of 1.2.

There are at least two well known confounding factors to which such an observational study such as this are prey:

* If the therapy is successful then the patient will have a marked change of life style.
* The reasons for which the therapy was prescribed in the first place might well pose a risk factor.

The second of these can be eliminated in a properly conducted double-blind randomised trial, but the first cannot.

A personal anecdote will illustrate how this factor works. Last year your bending author was reduced to life as a housebound cripple by a marked increase in arthritic inflammation. Eventually, therapy with Diclofenac and Co-Codomol restored an element of normal living and the patient celebrated by going out and digging over a large allotment. In retrospect this was rather foolish, a such violent activity after a period of forced idleness would have exacerbated any incipient heart disease. Fortunately, survival indicates that there was none.

It seems, however, more likely that the second of these confounding factors would be more important in this case, but more haunting is the possibility of confounding factors we have not thought of.

Which words in the truism "Correlation is not Causation" do the epidemiologists not understand? There is no reason to suppose from these tacky observations that any women at all have been killed by HRT.

Is there anything more despicable than pinning your claim to fame on scaring millions of women out of using a hugely liberating therapy? As for Cancer UK, which we all know from the constant begging letters, it could put the product of its suppliance to better use by supporting science rather than nonsense.


Prof. Brignell is too contemptuous of the study to comment at length on it above but he is making essentially the same point that I do: The very low percentage of women apparently affected makes it highly likely that the result is random noise. That some of the results are statistically significant rules out only one source of random fluctuation -- small sample size. A large enough sample will make ANY observed effect statistically significant. Statistical significance does not and cannot rule out other random (or non-random) events, effects and influences.

Prof. Brignell has some links in his article that I have not reproduced above. See the original for those links

This whole anti-HRT campaign is quite despicable. It aims to get women to take large risks (of osteoporosis etc.) in order to avoid tiny risks (of cancer)


Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.