The alarm bells were rung over talc last week, thanks to new research showing an increase in risk of ovarian cancer among women who regularly use talcum powder.
The new study compared about 1,400 women who had ovarian cancer with 1,800 healthy women to see if using talc had any effect on their risk of cancer. It found that women who used talc regularly had 36% higher risk of ovarian cancer.
The study also reported that certain genes affected this link, including the GSTT1 gene which helps to process chemicals in the body. The study found that the link between talc and ovarian cancer was stronger in women who lacked a working copy of this gene.
Is this cause for concern? Let’s take a look at the rest of the evidence.
What do we know?
Talcum powder is often made of a mineral called talc. Before the 1970s, talcum powder was often contaminated with asbestos fibres, which are known to cause cancer. But since then, all home products containing talcum powder are legally obliged to be asbestos-free.
Several studies have looked to see if there are any links between talcum powder and ovarian cancer. In general, their results have been inconsistent. In 2003, a group of researchers analysed the combined results of 16 different studies on talcum powder and ovarian cancer. Their results suggested that using talc could increase the risk of ovarian cancer. But they also showed that the risk of ovarian cancer didn’t go up further if women used larger amounts of talc.
This is strange – when it comes to things that cause cancer, risk is almost always related to exposure. For example, the more you smoke, the higher your risk of lung cancer becomes. Because this relationship wasn’t seen for talc and ovarian cancer, the researchers concluded that the link between talc and ovarian cancer was probably a statistical blip.
The new study is actually the first to suggest that women who use talc daily have higher risks of ovarian cancer than those who use is less frequently. That’s an interesting finding, but we need to consider it carefully especially since the previous 16 studies didn’t find the same thing.
Statistics aside, there are a few other reasons to be skeptical about a link between talc and ovarian cancer.
Many studies have found that women do not have higher risks of ovarian cancer if they use diaphragms (contraceptive caps) that are stored with talcum powder or have sex with partners using condoms dusted with talc. That is not what you would expect if talc could indeed cause this type of cancer, since caps or condoms would place the talc closer to a woman’s ovaries.
Talcum powder is also used in a medical technique called pleurodosis, where it’s applied to the sheets of tissue that cover the lungs. There is no evidence that this direct application of talcum powder to the body can cause cancer.
Some researchers have suggested that particles of talc could increase the risk of cancer by traveling into the ovaries, irritatating them and making them inflamed. We’ve blogged before about the fact that inflammation could increase the risk of some types of cancer, but that doesn’t seem to be the case for ovarian cancer. There is little strong evidence that other things which either trigger inflammation (like some infections) or reduce it (like aspirin) can affect the risk of ovarian cancer.
What’s the bottom line?
All in all, there is some suggestion from existing studies that talcum powder is associated with a higher risk of ovarian cancer but the evidence isn’t very strong. It is possible that any links are due to statistical blips, or that there is something else that talc users have in common that could affect their risk of ovarian cancer. Either way, there is clearly a need for more definitive research involving larger groups of people.
In the meantime, we understand that some people might still be worried about the safety of talcum powder. If that’s the case, the American Cancer Society suggest that women could alleviate their concerns by using cornstarch-based powders instead, which don’t contain talc.
The ovarian cancer charity Ovacome have also produced an excellent factsheet on the effects of talc and we highly recommend that you have a look at it. It goes into a bit more detail about some of the difficulties with the current evidence. It also concludes:
It is also important to keep in mind the fact that, out of the millions of women in England and Wales many of whom use talc, only a very small proportion will develop ovarian cancer each year. So even if talc does increase the risk slightly, very few women who use talc will ever get ovarian cancer.
In addition if someone has ovarian cancer and used talc, it seems highly unlikely that the use of the talc was the reason they developed the cancer. Further studies will be needed to work out exactly what role, if any, talc use plays in ovarian cancer.