The addictive component of cigarettes, nicotine, got more bad press recently when a report in the Jan. 2 issue of The Journal of Clinical Investigation (Vol. 111, No. 1: 81-90) called it a promoter of lung cancer.

Experts have long known that cigarettes are addictive and smoking them causes lung cancer. They have pointed to the tar in cigarettes as a primary cancer-causing agent, but now new evidence points to nicotine and its derivatives as promoters of cancer development and progression as well.

According to study author Phillip A. Dennis, PhD, of the National Cancer Institute (NCI) in Bethesda, Md., nicotine and a substance called NKK, a nicotine-derived nitrosamine, affect the epithelial cells of the lungs. These cells are exposed to inhaled smoke and are the cells in which lung cancer starts.

In the new study, Dennis and his colleagues found that stimulation by these substances resulted in the activation of a molecular pathway that promotes cell growth and survival.

By ramping up the pathway, abnormal cells are less likely to die when they show irregularities. This means that the "programmed" cell death, or apoptosis, needed to prevent cancer, is not taking place. The nicotine is actually helping these bad calls survive, Dennis said.

While experts noted these new, early findings, they pointed to the need for continued research. Any concerns raised by those questioning the use of nicotine replacement therapy (NRT) may be addressed by additional studies, said Thomas J. Glynn, PhD, national director of science and trends at the American Cancer Society.

"This certainly is a valuable study, conducted by an excellent research team," Glynn said. "While well-conducted, [it] is preliminary and [this area] needs further investigation in order to unravel the complex puzzle of carcinogenesis.

"Continuing to smoke is far worse than any short-term exposure to nicotine through NRT’s," Glynn said.

"As the authors themselves suggest, the most important action for a smoker to take is to quit, and nicotine replacement medications have proven effective in helping smokers do that," Glynn said.