Breast Cancer Linked to Nicotine, Alcohol

The results of two, highly relevant bodies of research regarding breast cancer have been revealed during the last few days.

Both studies, which emphasize the definitive role that lifestyle factors can have in developing the disease, are being published in the Journal of the National Cancer Institute.

Nicotine and Cell Receptors

Researchers have known for a long time that smoking increases breast cancer risk, but that risk is typically associated with other carcinogens in cigarettes, rather than with nicotine.
However, researchers at Tapei Medical University in Taiwan took a closer look at nicotine specifically, and they found a clear association with breast cancer risk.

Specifically, the scientists discovered that the actual risk comes from nicotine binding to a certain cell receptor, called the nicotinic acetylcholine receptor (nAChR).  Such binding with this receptor is what fuels smoking addiction.

For the breast cancer study, Yuan-Soon Ho and his colleagues examined 276 breast tumor samples to determine if subunits of nAChR were over produced in breast cancer tissue as opposed to normal cells surrounding the tumor.
 
Indeed, the researchers discovered that a subunit of the receptor, referred to as the alpha-9 subunit, was overproduced.  They also learned that production of a9-nAChR was higher in advance stage breast cancer.

Additionally, “treating” normal cells with nicotine led to breast cancer.

Per the study abstract, the authors write, “These results imply that receptor mediated carcinogenic signals play a decisive role in biological functions related to human breast cancer development.”

Alcohol Linked to Breast Cancer Subtypes

Another study, which examined 88,000 post-menopausal women who took part in the Women’s Health Initiative from 1993-1998, revealed that women who drink one alcoholic beverage a day have a higher risk of developing estrogen receptor- and progesterone receptor-positive breast cancers.

Even more specifically,  although women who drank 7 or more drinks per week had an increased hormone receptor-positive breast cancer risk, this elevated risk was only associated with the breast cancer subtype lobular carcinoma; the risk of ductal carcinoma, a more common subtype, was unaffected.

 The risk of malignant tumors that are both estrogen and progesterone receptor-positive increased by 8% per alcoholic drink per day; estrogen receptor- positive and progesterone receptor-negative tumor risk rose 12%.

In response to the study, Dr. Gretchen Kimmick, associate professor of medicine and Duke University Medical Center tells BusinessWeek:  “Minimizing alcohol intake will decrease breast cancer risk, and there are a lot of things we know that increase risk similar to what alcohol does.  No one factor in particular is going to cause breast cancer in itself.  They’re probably all related and we’re trying to figure out what the multiple factors are that cause breast cancer for women.”

Certainly, there are other factors which affect risk, such as the age menses begins and genetic predisposition, but at least women can take a modicum of comfort in knowing that there ARE some risk factors they have control over.