Talkpoeder en het risico op eierstokkanker*
Volgens een Amerikaanse studie onder ruim 3.000 vrouwen hebben zij die dagelijks talkpoeder gebruiken in de genitale streek tot
40% meer kans op eierstokkanker hebben. Zelfs zij die het slechts 1x per week
gebruikten hadden 36% meer kans. Afhankelijk van genetische aanleg kan het verhoogde risico wel oplopen tot 300%. Het is niet de eerste studie die een dergelijk verband suggereert, maar tot nu toe heeft geen enkele studie een echt
verband kunnen aantonen. Uit deze studie blijkt dat het aantal kankergevallen toeneemt met
een toenemende hoeveelheid talkpoeder en hoe vaker het gebruikt wordt. Ook bleek er een verband te bestaan tussen de frequentie van het
talkpoedergebruik en de ernst van de eierstokkanker. Gelet op de structuur van talkpoeder denken de wetenschappers dat talkpoeder een gelijkaardig effect geeft als asbestvezels. Alhoewel verder onderzoek nodig is om een oorzakelijk verband aan te tonen, raden de onderzoekers aan dat vrouwen die zich ongerust maken, beter geen talkpoeder meer gebruiken in de genitale streek.
Frequent Use of Talcum Powder Near Private Parts May Cause Ovarian Cancer
According to a latest study conducted at the Harvard Medical School in Boston, women who used talcum powder around their private parts daily have a 40% higher risk of getting ovarian cancer. Even those who only used it once a week experienced a 36% higher risk. Although concerns over the use of talc had previously already been surfaced through other studies, these latest figures obtained suggest that the risks are much higher than thought
before.
Details of Study
For this Harvard study, researchers looked at data from two previous studies, the New England Case-Control Study (NECC) and the Nurses Health Study (NHS), to try and locate a link between the use of talcum powder on the genitals and the risk of contracting ovarian cancer. They also tried to see how certain genetic factors might affect this risk.
All in all, the cases of over 3,000 women were studied, with 1,385 of them having had ovarian cancer and another 1,802 women not having contracted the disease. Both the previous studies had collated information on talc use by the women, including how frequently they used it and on which areas of the body.
The study was led by Dr Margaret A. Gates and funded by the National Cancer Institute and the National Institutes of Health.
Findings of the Study
The key finding of the Harvard study was the significantly higher risk – 1.4 times – of getting ovarian cancer for those who used talc daily. Correlation was also noted between more regular usage of talc with the development of serious and invasive cancer. Note that the findings of this study relate only to the use of talcum powder near the genitals, and do not apply to use on the rest of the body.
Further findings from the study was that women who have the gene glutathione S-transferase M1, or GSTM1, but do not have the gene S-transferase T1 ( GSTT1), had almost three times as high the risk of developing tumors. This genetic combination is believed to be present in about 10% of Caucasian women. Women who were only lacking the gene GSTT1 also had a higher cancer risk. This higher risk also applied when the study team considered serious, invasive cancer, which is one of the three main types of ovarian cancer.
According to the study team, extensive research had been previously carried out and some studies have found "modest association" between talc use on the genital area and higher risk of ovarian cancer. And this association has been controversial, because of factors such as "a lack of a clear dose-response with increasing frequency or duration of talc use, the possibility of confounding or other biases, and the uncertain biological
mechanism".
And because the latest study provides an observed dose-response – higher talc use frequency being linked with greater ovarian cancer risk, including for serious invasive cancer – the research team feels that their findings give further support to the long-held idea that genital exposure to talcum powder increases the risk of ovarian
cancer.
As for the findings on the effects of different genes, the study's findings suggest that one's biological response to talcum powder may be affected by genes which are involved in its detoxification
pathways.
The study team had hypothesized that, because talc, which is made through crushing, drying, and then milling of a mineral called hydrous magnesium silicate, has similar chemical properties to asbestos, it was possible that the same molecular and genetic pathways could play a part in the body's ability to cope with these substances. Specific combinations or variations in certain genes would mean that a person was less able to metabolize or detoxify carcinogens – it would then follow that these people should have a higher risk of ovarian cancer with increased talc
exposure.
Asbestos is known to cause a deadly form of lung cancer.
Limitations of Study
It is important to note that the said study, which was published in the journal Cancer Epidemiology, Biomarkers and Prevention, has a few limitations. Firstly, the two studies which it drew data from had different methods of data collection. Also, the participants of the NHS study were also only asked once on their talc usage, and they might thus not have been classified
correctly.
In addition, it is not really possible to be sure if exposure to talc had in fact preceded ovarian cancer diagnosis, i.e. that the use of talcum powder played a part in the development of the disease.
While some factors, such as age, use of oral contraceptives, body mass index and menopausal status, were taken into account and adjusted for, there are probably also some other important ovarian cancer risk factors which were not accounted
for.
Does talcum powder really increase ovarian cancer risk?
Each year, more than 6,000 women in the United Kingdom are diagnosed with ovarian cancer. In the United States, more than 20,000 women were diagnosed with ovarian cancer in 2004, while more than 14,700 died from the disease that year.
Some risk factors, besides general lifestyle and dietary habits, include family history, being overweight, use of hormone replacement therapy, relatively earlier start of menses, and having already been diagnosed with breast cancer.
Despite the limitations of the Harvard study, when we look at the overall scheme of things, and put its findings alongside the evidence which had been provided by previous studies, it does appear that talc use is linked to ovarian cancer.
For example, laboratory tests had previously already shown that ovarian cells exposed to talc tend to multiply more rapidly, which is something very characteristic of malignancy. But there had been no clear evidence to affirm scientists' fear that particles could actually move along a woman's reproductive tract such a distance, from the genitals all the way to the ovaries. However, in 2007, doctors at Harvard Medical School found small powdered particles in the pelvis area of a woman with late-stage ovarian cancer. The woman was 68 years old and had used talcum powder everyday for the past 30 years or so.
What Next
At the end of a long hard day at work, take a warm, relaxing bath, dry yourself, and then sprinkle on some talcum powder to feel even better. That is probably what some of us do.
However, based on evidence available so far, Gates has advised women to avoid using talcum powder in the genital area until more research has been carried out.
But would that be overreacting? Dr Jodie Moffat of Cancer Research UK reminded us "it is important to remember that very few women who use talcum powder will ever develop ovarian cancer". The website of the American Cancer Society echoes this, stating that "only a very small minority of women who have used talcum powder will ever develop ovarian cancer".
About half the people reading this article will never get ovarian cancer, not because they are immune to cancer, but because they do not have ovaries. But it is still a stark reminder of how many common and seemingly harmless everyday items in our lives today are adding to our risk of many diseases. The cleaner and more natural we can get, the safer we will
be.
As far as the use of talcum powder goes, while more conclusive research may still be needed, in the meantime, women will have a decision to
make. (Januari
2009)
