Nicotine in has been linked to breast cancer for the first time as researchers find the substance may promote the growth of tumours.
Nicotine is the chemical in cigarettes which causes addiction and has now been linked to the development of breast cancer.
Previously smoking was not thought to be a major cause of breast cancer although it is known to increase the risk of several other forms of the disease.
Researchers at Taipei Medical University examined 276 samples from human breast cancer tumours and found the cells had large numbers of receptors which nicotine was able to attach to when compared with normal cells.
They also found that when normal cells were treated with nicotine, it promoted the development of cancer characteristics.
Because the findings were linked to nicotine and not the usual carcinogenic chemicals in cigarettes, it raises questions over nicotine gum, inhalers and patches, that many use to supposedly help them to quit smoking. These products in fact actually just keep them addicted to nicotine.
The findings are published in the Journal of the National Cancer Institute.
In an accompanying editorial, Dr Ilona Linnoila, of the Center for Cancer Research at the National Cancer Institute, writes that the study “suggests not only that smoking could be causally related to breast carcinogenesis but also that nicotine could directly contribute to the molecular mechanism of carcinogenesis in addition to indirectly contributing by promoting addiction to smoking.”
