Breast cancer risk and hair dye

This statement from the National Institutes of Health (NIH) recently rocked the breast cancer community: Scientists at the National Institutes of Health found that women who use permanent hair dye and chemical hair straighteners have a higher risk of developing breast cancer than women who don't use these products. The study, published online on Dec. 4 in the International Journal of Cancer, suggests that breast cancer risk increased with more frequent use of these chemical hair products.

My inbox was flooded with worried emails, and I have had numerous conversations with women since then. This study, using data from more than 46,000 women in the Sister Study upended what has always been the party line. For years, we have told women that there was no known risk from coloring or straightening their hair. I personally have reassured countless women, who were unhappy with their post-chemo gray curls, that they could color their hair as soon as there was enough to handle. This is probably still true, but this study does raise some concerns.

Scientists at the National Institute of Environmental Health Sciences (NIEHS), part of the NIH, found that women who had regularly used permanent hair dye in the year prior to joining the study were 9% more likely than others to develop breast cancer. The risk was greater for African American women. For them, using permanent hair dye every five to eight weeks (a typical timing for women who color their hair) was associated with a 60% increased risk of breast cancer vs. 8% for white women. Little or no increase in breast cancer was found from the use of temporary or semi-permanent coloring.

Another related finding was the association between the regular use of chemical hair straighteners and breast cancer. Women who used these products every five to eight weeks were about 30% more likely to develop the disease. There was not a significant difference in this number between African American and white women, but the use of hair straighteners is more common among African American women.

As is the case in considering any study, the first thing is to step back, take a deep breath, and don't jump to conclusions. Remember that these numbers are about associations, not about causes. We don't know about the myriad of other factors that may have contributed to the increased risk of breast cancer. What were all these women eating and drinking? Were they exercising regularly? Did they have healthy body weights? What were their other medical issues?

This one study is not going to change the advice given to women about coloring their hair. We all know that there are many chemicals in hair products, but we also know that there are many chemicals in many parts of our daily lives. There is not a straight line between coloring your hair and developing breast cancer. There is not a line at all between coloring your hair and increasing the risk of a recurrence of breast cancer; this has not been studied, but it is very unlikely that the data could be clear and strong.

Here is what we must remember: Especially after breast cancer, we need to do all that we can to regain our confidence and our trust in our bodies. We need to look our best and to move forward in our lives with purpose and agency. If you feel better about yourself when your hair is colored, do it! Yes, pay attention to self-care and remember about regular exercise and weight maintenance and moderate alcohol intake. And remember to fasten your seat belt and floss your teeth daily. In other words, continue with common sense and care.