Nicotine, Not Just Smoking, Linked to Breast Cancer
Smoking and tobacco use has long been associated with the development of cancerous tumors, particularly in the lung, mouth, and esophagus, but the nicotine contained within has now been implicated as one of the chemicals that can trigger the development of breast cancer.
Cigarettes Contain Over 60 Chemicals Linked to Cancer
Cigarettes contain at least 60 cancer-causing substances, including carbon monoxide, tar, and arsenic, so quitting smoking can reduce the risk of cancer. Avoidance of secondhand smoke is also important, as the chemicals have been found in studies to reach breast tissue and are found in breast milk.
However, this latest study indicates that even nicotine-replacement products that help patients quit smoking (such as gums, patches and the electronic cigarette) could be contributing to the development of cancer as well.
Researchers from Taipei Medical University studied the effects of nicotine with both normal cells and breast cancer cells. The 276 samples studied were donated to the hospital from anonymous donors. The team found that normal cells treated with nicotine developed cancer characteristics.
Dr. Yuan-Soon Ho found that human breast cancer cells consistently produced the alpha-9 subunit of the nicotine acetylcholine receptor (a9-nAChr). The expression was higher in advanced-stage breast cancer compared with early-stage cancer. This suggests that nicotine binding to the receptor may not only contribute to smoking addiction, but may also directly promote the development of breast cancer.
Older women who smoke cigarettes or who have smoked for long periods of time may be up to 40% more likely to develop breast cancer than women who never smoked, according to a study conducted at the Fred Hutchinson Cancer Research Center in Seattle. The study also found that smoking women who were also using estrogen and progestin hormone therapy had double the risk of cancer development.
Breast cancer incidence in the United States is 1 in 8 women, according to BreastCancer.org.
Chia-Hwa Lee, Ching-Shui Huang, Yuan-Soon Ho et al. Overexpression and Activation of the α9-Nicotinic Receptor During Tumorigenesis in Human Breast Epithelial Cells.Journal of the National Cancer Institute, 2010; DOI:10.1093/jnci/djq300