Lung cancer remains the leading cause of death in men and women in the US, and over 90% of lung cancers are caused by smoking. Quitting smoking is the single best way to reduce the risk of developing lung cancer and those who quit sooner rather than later further reduce their risk of developing this devastating illness.

A recent study printed in the British Medical Journal (Parsons, A. BMJ.com) gives smokers who develop lung cancer new hope. Data from this study indicate that not only do the toxins in tobacco smoke cause cancer, but that they also may cause the disease to progress once it develops.

This is an important finding. Quitting smoking can be difficult and uncomfortable. Because of this and the poor prognosis for surviving lung cancer, many physicians treating patients who smoke are reluctant to advise them to quit. This study provides good evidence that failure to provide advice to quit, especially when lung cancer is discovered in its early stages, may be a huge mistake. Here’s why.

Lung cancer is identified early enough to be treated with curative approaches in about 20% of patients. For these patients the prognosis for surviving longer than 5 years is relatively good. Findings showed that there was a three-fold increase in mortality (dying) among those who continued to smoke as well as a four-fold increased risk of developing a secondary tumor.

It is important to emphasize that the data from this study involved in-depth analysis from 10 randomized controlled studies and great effort was made to further control for other factors that might explain improved survival rates for those who quit smoking after being diagnosed with early stage lung cancer. For example, analysis was conducted to assess whether the improved survival rates were not a result of preventing other common causes of death from smoking, such as cardiovascular disease. They were not.

So if you are a smoker or you know a smoker who has recently been diagnosed with lung cancer, the best thing you can do is quit or advise your friend or loved one to quit. Evidence-based smoking cessation treatment, like the Quit for Life® Program (brought to you by a collaboration between the American Cancer Society and Free & Clear), is widely available, easily accessible, and very cost-effective. Most importantly it saves lives!

If you are a health care provider and encounter a patient with lung cancer who smokes, there is now good evidence that advice to quit is a critically important part of effective treatment. This is especially true if the disease is caught in its early stages. The 2008 Clinical Practice Guideline Update Treating Tobacco Use and Dependence provides clinicians with information on how to intervene with smoking patients that can be printed or downloaded.