There is no direct connection between deodorant and breast cancer. This myth started through a combination of issues. Doctors asked women not to wear deodorant when coming in for mammograms, which women may have interpreted to mean there was a connection between wearing deodorant and breast cancer. High levels of parabens have also been found in cancer tissue, and deodorants contain parabens, so many extrapolated that the parabens may have entered the body through small nicks in the skin from shaving. Finally, some people feel that antiperspirants, not deodorants, may lead to the development of breast cancer because they prevent toxins from leaving the body through sweat.
These tentative links do not provide proof that wearing deodorant leads to developing breast cancer. Doctors routinely asked women to refrain from wearing deodorant when receiving a mammogram because the residue could obscure the results. Parabens are found in many different types of cosmetic and hygiene products, not just deodorant. The estrogen like effect of parabens is much weaker than actual estrogen, making it unlikely that parabens could be blamed for breast cancer.
The thought that there was a link between deodorant and breast cancer spread quickly on the Internet and through email. While researchers have noticed connections, such as the fact that the earlier a woman started to shave and wear antiperspirant, the younger she was when she developed breast cancer, these studies do not prove causation, meaning there is no proof that wearing antiperspirant causes breast cancer to develop.
The final point to keep in mind is that the links between deodorant and breast cancer appear even weaker than possible links between wearing antiperspirant and developing breast cancer. Deodorant is made mostly of alcohol, and kills bacteria that causes odor from sweat. Antiperspirant is a combination of ingredients that block the pores, preventing sweat from leaving the body. Most concerns about breast cancer developing from underarm hygiene focus on the use of antiperspirant rather than deodorant.
Both the National Institutes of Health and the National Cancer Institute cite that there are no conclusive studies that indicate any link between the use of antiperspirant or deodorant and breast cancer. The Food and Drug Administration, which is responsible for regulating the cosmetic industry, also does not have any evidence of a link between the deodorant use and the development of breast cancer. Anyone with concerns should speak with her family doctor.