I saw a warning on the Internet that underarm antiperspirants and deodorants may cause breast cancer. The warning said that these products contain harmful substances, which can be absorbed through the skin or enter the body through nicks caused by shaving. Is this true?

No, this is a myth. The National Cancer Institute (NCI), the nation's chief cancer research agency, is not aware of any evidence of a link between use of antiperspirants and deodorants and the development of breast cancer. Also, the U.S. Food and Drug Administration, which regulates food, cosmetics, medicines, and medical devices, has no evidence that ingredients in underarm antiperspirants or deodorants cause cancer.

Source:  "Ask the CIS" by the Cancer Information Service.  "Ask the CIS" is distributed by the Cancer Information Service (CIS) of the Heartland, which serves Kansas, Nebraska, Missouri & Illinois. The CIS is a program of the National Cancer Institute. Call the CIS toll-free at 1-800-4-CANCER (1-800-422-6237) between 9 a.m. and 4:30 p.m. local time.