It is general knowledge that nicotine causes addiction, but now it has been linked to the development of breast cancer.  Smoking was not thought to be a major cause of breast cancer even though it is known to increase the risk of sveral other forms of the disease.

In a study conducted at Taipei Medical University, researchers examined 276 samples from human breast cancer tumors and discovered that the scells had large numbers of receptors to which nicotine was able to attach, as compared with normal cells.

They also discovered that normal cells treated with nicotine began developing cancer characteristics. 

Since the findings were linked to nicotine, and not the usual carcinogenic chemicals in cigarettes, it raises questions over the use of nicotine gum, inhalers and patches that many people use to help them quit smoking.