How much does using talc increases your risk of developing Ovarian Cancer? Talc is pretty widely used, so if true this is a pretty big story and also rather bad news. It is such handy and useful stuff it would be a great shame if we had to stop using it and of course it would also be bad if people are contracting cancer who otherwise would not. The only people who would be pleased would be the people behind the campaign for safe cosmetics. They have been going since 2002 and have yet to find any unsafe cosmetic product.
In fact the cosmetic industry has probably got just about the best track record of consumer safety of any big industry. This isn’t because the people who create cosmetics are exceptionally careful or remarkably skilled. It’s just a fact of life. You use cosmetics in very low quantities, you don’t eat them, you don’t drive around very fast in them and you don’t plug them into the mains electricity. Basically there just isn’t really that much that can go wrong.
So it isn’t surprising that the Campaign for Safe Cosmetics have had a thin time of it trying to find really anything to campaign about, even though they are obviously very well funded as a quick look at their very swish website and high production value videos shows. But with talc they might well be thinking that they have finally managed to pin some actual damage to actual consumers onto a proper mainstream product. An American jury recently found Johnson and Johnson guilty of causing the death by cancer of a customer who used Johnson’s Baby Powder. The family have been awarded millions and maybe at last the campaign have an actual case.
The founder of the campaign, Stacy Malkin, was on Twitter issuing advice straight away. Avoid talc in the pelvic region and on babies she said. They have a whole web page devoted to the subject. And if it can kill you, on the face of it then this sounds like good advice.
This looks set to be a big story, because there are many other plaintiffs lining up to bring similar cases. If US juries continue to dish out big payouts and the appeal courts uphold them then I think we may well have seen the end of talcum powder as a mass market consumer product.
And if talc is carcinogenic we should be glad to see the back of it. Losing a popular product is a small price to pay for reducing the risk of cancer, and the cosmetic companies shouldn’t have been selling something dangerous in the first place. It is only right that they should pony up to compensate their victims.
So let’s try and quantify just how big this risk is.
The study that triggered it all off was done in 1982. This was a small retrospective study. A retrospective study is one which looks at data on women who had had ovarian cancer and compares it to a group of similar women who didn’t. Retrospective studies are a lot less reliable than prospective studies where you set the whole thing up first and track it to see what happens. When you do your study retrospectively you are hoping that you have picked two comparable groups, but you are relying on the memories of the people involved which is risky, and your selection is inevitably influenced by your preconceptions. Nonetheless, it is a tool that can be used if you are aware of its limitations. This study suggested that women who had used talc were twice as likely to get ovarian cancer as those that didn’t. This is a pretty big difference – so it was worth investigating further.
When you get a surprising result the first step is to think through what the possible explanations are. The one that springs to mind first is that the talc is causing the cancer and that we need to get out there and stop people using it. We all have a built in self survival bias and are inclined to look out for danger. But there are quite a few other possible explanations. The talc could be triggering a condition that is already there, and so talc users get diagnosed sooner but were always going to get it all along.
Or it could be that talc use is correlated with something else. For example if you spend more time applying talc you might increase your exposure to light, which is a known carcinogen. Or maybe ovarian cancer creates symptoms before diagnosis that talc is good at treating, and this means that cancer sufferers just find talc more appealing.
And we can’t be sure that the problem is simply talc. It might be the chemical nature of talc, or it might be nothing to do with what the talc is composed of and everything to do with the particles size. In which case if people stop using talc but use something else instead it might make no difference. It could even make things worse.
So we have a small study that might not be reliable and even if it is is open to interpretation. This isn’t to be in any way critical. That is just the way things work. If talc is a dangerous ingredient, it is not going to be established by one study. A paper is there to report what has been found, but it usually takes a while for a picture of what is going on to emerge. Since then there have been about 20 investigations into various aspects of the question of whether or not talc is harmful. None of them have shown talc in as bad a light as the very first one – I have picked out what I think are the key ones when it comes to assessing just how risky talc is.
The next study carried out by much the same team behind the first finding was published in 1999 and was a bit bigger and was based on more recent exposure, so it had less chance of getting it wrong. It still showed an association. But the association was much less strong. This time it was only a 20% difference. You’d still be worried, but a 20% increase in risk is a lot less than doubling it. Incidentally, f you knew nothing about medical research before watching this video, there is something to learn right there. The same team studying the same problem using perfectly good scientific practices can come up with two pretty different answers to the same question. That’s the way these things work. It is best not to put too much reliance on data from a small number of studies.
Another large study, but still retrospective came out in 2008. This again had an association between talc use and cancer of about 20%. In fact it was just under. And the statistics indicated that there was a one in twenty chance that there was in fact no difference between the two groups. So although it did confirm the 1998 study to some extent, it still left plenty of room for doubt.
There have since been two more retrospective studies. One found no association, the other came up with similar numbers to the earlier study, i.e., not a huge effect and rather weak statistical support for that effect. The authors themselves weren’t particularly happy with their numbers. On the possibility of talc being the cause of ovarian cancer they said “no stronger adjective than “possible” appears warranted at this time.”
These kinds of study are always going to be weak. What you really want is a double blind study that shows that the more talc you apply the more incidences of cancer you get. But you can’t do that study. For a start, there is no possible placebo. You can’t tell if you are taking a sugar pill or a pill with an active ingredient in it. You can certainly tell whether or not you are using talc. And in any case, medical ethics would probably prevent you carrying out this trial. If you couldn’t show reasonable grounds to believe that talc was a carcinogen there would be no reason to carry it out. If you could, then it would be unethical to deliberately expose women to that risk.
But in 2010 we got the best we are likely to get. This was a prospective study following a large group of women and seeing how their experiences pan out. This was a very big bit of work involving 66000 subjects. The result was that no association between talc use and ovarian cancer was found. It looked like we had our answer.
Just to complicate matters, they looked at subsets of the data as well. When you looked just at the post menopausal women and ignore all the other results, a slight association could be found. It was about 20%. Our brains love patterns, and it is tempting to see in this the confirmation of earlier data and an explanation of the whole story. It does look like there is a risk of talc increasing your risk of ovarian cancer by about 20%, but only when you reach the menopause. Talc turns out to be about as mild a carcinogen as they come, only causing a slight risk and only once you are well into middle age. But yes, it just about sneaks into the category and becomes sort of the Jamaican bob sleigh team of carcinogens.
I have to say though, that things are rarely that simple. To me it looks a lot more like a case of the problem that bedevils this kind of study both in medicine and in biology in general. Just because two sets of numbers show the same pattern, or are correlated to use the statisticians word for it, it doesn’t prove that one causes the other. Correlation is not equal to causation is how this is often put. There are plenty of comical examples of this. For example the number of people who are drowned falling into a pool in a given year for example correlates with the number of films Nicolas Cage appeared in that year.
More seriously, for some time it was believed that smoking increased your risk of committing suicide. This wasn’t particularly controversial. We all know that smoking is bad so seeing another charge added to the sheet didn’t seem a big deal. There was even a plausible mechanism. Smoking reduces serotonin levels, so that might well be depressing. It was only when somebody looked at the correlation between smoking and being murdered that doubt was cast on the conclusion. Smoking increases your risk of being murdered in exactly the same way as it does your risk of committing suicide. So in fact the chances are that smoking is more prevalent in the kinds of tough environments where murder rates, and suicide rates are high.
So even if it had turned out that the risk of getting cancer had been strongly correlated with the use of talc, that would not have been enough to prove the link between the two. You’d still need to have at least some plausible explanation of how it might be working before you could draw a conclusion that was more than just speculation. When you start looking at subsets of the data you increase the risks of picking up a false correlation considerably. After all there is a lot that changes when you reach the menopause, and increased use of talc might well be one of them.
At the very least, you have to conclude that whatever is going on between talc and ovarian cancer is clearly not a simple story if there actually is anything going on at all. The stock trade of scaremongers like the Campaign for Safe Cosmetics is to ignore the complexities, cherry pick the data to find the studies that support the case they are trying to make and ignore the correlation not equalling causation fallacy altogether. Watch out for that. The same tactics work well for lawyers trying to get payouts for their clients in jury trials as well.
I’ll put all the references up in the blog post so you are welcome to plunge in and think about it yourself. I have a feeling that in the future when there is more data, better understanding of cancer itself and better tools for assessing a person’s history of exposure to talc and other possible relevant factors, that the apparent 20% increased risk that you might be concerned about will be revealed to be simply not there. Certainly the most recently published study, from 2012, showed no association at all. Any explanation for what is going on needs to explain why the association is not always found.
But you might be saying, well it’s all very well for you to say that. You don’t have ovaries do you Colin? And I don’t want to take the risk. That is fair enough – our tolerance of risk is a very individual thing and I have no right to impose my opinion on anyone else. But I started this review of the literature not to assess whether or not talc was carcinogenic but to work out the risk of using it. What exactly does a 20% increase in the risk of Ovarian Cancer look like. Let’s run the numbers.
Ovarian cancer is rare. The number of new cases of ovarian cancer was 12.1 per 100,000 women per year based on 2008-2012 cases. It is most frequently diagnosed among women aged 55-64, exactly the age range where the possible risk kicks in. So basically if we accept the worst case scenario using talc might increase that figure to 14 or 15 per hundred thousand from the age of about 50 onwards.
So using talc might increase your risk of getting ovarian cancer very slightly if you are approaching your fifties. I personally cannot distinguish between a risk of 12 in 100,000 and 15 in 100,000 and so wouldn’t myself trouble about giving up talc. One thing I wouldn’t do though is switch to another powder. If we concede that talc constitutes a risk then we have to also allow that alternatives such as corn starch may well pose the same risk or even a greater one. We just don’t have enough data to make any comparison between the two. So if talc worries you, so should all other powders.
Talc remains fully legal and approved in both the United States and Europe. I really can’t see any case for banning or restricting it. I suppose a warning on the pack might be arguable, but it is very difficult to see how a warning could be worded over such a low risk and one that isn’t even very well established in the first place. I think it would simply alarm people to no good purpose.
I hope you have found this interesting and enlightening. Researching this topic was an education for me. One of the things I realised by plunging deeply into this case is just how hard it is to study the long term effects of chemicals to which we are exposed over a prolonged period. Talc has come out of it pretty well. As a cosmetic formulator I don’t have the luxury of being whimsical about product safety. I always have to be ready to abandon an ingredient at any time if a new problem is identified with it. Talc might still turn out to have some hitherto unsuspected downside, but it looks a lot safer to me now than it did before I troubled to look at the data in detail. It would be a shame if the current controversy were to drive it off the market. It is often pointed out that being natural doesn’t make something safe, and this is true enough. But talc as it happens looks very much to me like it is both.
|Cancer Volume 50, Issue 2, pages 372–376, 15 July 1982 Ovarian cancer and talc. A case-control study Daniel W. Cramer MD, William R. Welch MD, Robert E. Scully MD and Carol A.Wojciechowski RN||Original study with 215 cancer sufferers compared to 215 non-cancer sufferers. It found an association of 1.9.||http://onlinelibrary.wiley.com/doi/10.1002/1097-0142(19820715)50:2%3C372::AID-CNCR2820500235%3E3.0.CO;2-S/abstract;jsessionid=D11463F92D04C7FAFF2A6BB322485217.f02t04|
|International Journal of Cancer Volume 81, Issue 3, pages 351–356, 5 May 1999 Genital talc exposure and risk of ovarian cancer Daniel W. Cramer, Rebecca F. Liberman, Linda Titus-Ernstoff, William R. Welch3, E. Robert Greenberg, John A. Baron and Bernard L. Harlow||Follow up by team who did the original work, this time finding an association of about 1.2||http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1097-0215(19990505)81:3%3C351::AID-IJC7%3E3.0.CO;2-M/abstract|
|International Journal of Cancer Volume 122, Issue 1, pages 170–176, 1 January 2008 Talcum powder, chronic pelvic inflammation and NSAIDs in relation to risk of epithelial ovarian cancer Melissa A. Merritt, Adèle C. Green, Christina M. Nagle and Penelope M. Webb||Controlled study with 1600 cancer patients compared to 1600 random population members.
“We confirmed a statistically significant increase in ovarian cancer risk associated with use of talc in the pelvic region (adjusted odds ratio 1.17, 95% CI: 1.01–1.36)”
|Cancer Causes Control. 2011 May;22(5):737-42. doi: 10.1007/s10552-011-9746-3. Epub 2011 Mar 10. Genital powder exposure and the risk of epithelial ovarian cancer.
Rosenblatt KA1, Weiss NS, Cushing-Haugen KL, Wicklund KG, Rossing MA.
|800 versus 1300
“A modest association of ovarian cancer with this exposure was seen in our study and in some previous ones, but that association generally has not been consistent within or among studies. Therefore, no stronger adjective than “possible” appears warranted at this time.”
|Am J Obstet Gynecol. 1996 May;174(5):1507-10. The relationship between perineal cosmetic talc usage and ovarian talc particle burden. Heller DS, Westhoff C, Gordon RE, Katz N.||24 women, 12 who reported they used talc and 12 who didn’t were scanned. All 24 had talc in their ovaries.||http://www.ncbi.nlm.nih.gov/pubmed/9065120|
|Cancer Epidemiol Biomarkers Prev May 2010 19; 1269 Perineal Use of Talcum Powder and Endometrial Cancer Risk Stalo Karageorgi, Margaret A.Gates, Susan E.Hankinson and Immaculata De Vivo||Big study including over 66000 women finding no overall association. An association was shown in subset of post-menopausal women of about 20%.||http://cebp.aacrjournals.org/content/19/5/1269.full|
|Eur J Cancer Prev. 2008 Apr;17(2):139-46. doi: 10.1097/CEJ.0b013e32811080ef.
Perineal talc use and ovarian cancer: a critical review.
Muscat JE1, Huncharek MS.
|A review concluding that there is no case that talc causes cancer. (I have stated the case against more strongly than this author because of the point I was trying to make. I have included it here just to show I am aware of it in case anyone quotes it to rubbish what I am saying.)||http://www.ncbi.nlm.nih.gov/pubmed/18287871|
|Cancer Causes Control. 2012 Mar;23(3):513-9. doi: 10.1007/s10552-011-9894-5. Epub 2012 Jan 14.Use of talcum powder and endometrial cancer risk. Neill AS1, Nagle CM, Spurdle AB, Webb PM.||1400 with cancer and 800 controls. No association found.||http://www.ncbi.nlm.nih.gov/pubmed/22245995|
|JNCI J Natl Cancer Inst (2000) 92 (3): 249-252. doi: 10.1093/jnci/92.3.249 Prospective Study of Talc Use and Ovarian Cancer Dorota M. Gertig, David J. Hunter, Daniel W. Cramer, Graham A. Colditz, Frank E. Speizer, Walter C. Willett and Susan E. Hankinson||Only prospective study, and by far the largest “Our results provide little support for any substantial association between perineal talc use and ovarian cancer risk overall; however, perineal talc use may modestly increase the risk of invasive serous ovarian cancer.”||http://jnci.oxfordjournals.org/content/92/3/249.full|
|Am J Epidemiol. 1989 Aug;130(2):390-4.
A case-control study of borderline ovarian tumors: the influence of perineal exposure to talc.
Harlow BL1, Weiss NS.
|Am J Obstet Gynecol. 2000 Mar;182(3):720-4.
Perineal application of talc and cornstarch powders: evaluation of ovarian cancer risk.
Whysner J1, Mohan M.
|Cornstarch has not been as widely studied as talc, but there is no real reason to believe that corn starch is a problem.||http://www.ncbi.nlm.nih.gov/pubmed/10739536|
Thanks to Wikipedia for the talc image