Double the Cancer Behind the Smoke

Smoking increases the risk of developing a second cancer among cancer survivors

(RxWiki News) Smoking is known to increase the risk of cancer. Do smokers who survive their first cancer have to worry about developing another cancer?

According to a recent study, smokers who had been diagnosed with one cancer had a higher risk of developing a new cancer in the future compared to people who had never smoked.

Cancer survivors who quit smoking had a lower risk of developing a second new cancer when compared to those who continued smoking.

"Quit smoking to reduce your cancer risk"

This study was conducted by Dr. Takahiro Tabuchi from the Center for Cancer Control and Statistics at Osaka Medical Center for Cancer and Cardiovascular Diseases in Japan.

The aim of this study was to find out if cancer survivors with a history of smoking have a higher risk of developing subsequent cancers.

The researchers looked at 29,795 patients in Japan who had been diagnosed with cancer for the first time between 1985 and 2004. They examined records of these patients until the end of 2006 for another diagnosis of cancer at a primary site.

The second diagnosis of cancer at a primary site means that the patients had developed a new cancer which was not due to spread or recurrence of the cancer diagnosed earlier.

The researchers found that people who had a history of smoking had a 59 percent higher risk of developing another primary cancer as compared to those who had never smoked.

People who had smoked also had a 102 percent higher chance of developing a smoking-related primary cancer as compared to non-smokers.

Compared to cancer survivors who were non-smokers, cancer survivors who had ever smoked also had a significantly higher risk of oral, esophageal, stomach, lung and blood cancers at a primary site regardless of where their first cancer had occurred.

The researchers concluded that overall, smoking increased the risk of not only the first cancer but also a second cancer which may be unrelated to the first. They also found that cancer survivors who quit smoking up to three years before diagnosis had a lower risk of developing these cancers compared to those who continued smoking.

The study authors noted a few limitations of their research. How much a person had smoked was not taken into account.

Plus, the researchers may have been unaware of other actions taken to prevent cancer by patients who quit smoking. As such, the study may have inflated the effects of quitting.

According to dailyRx Contributing Expert and Professor of Medicine and Pathology and Associate Director for International Programs at the University of Colorado Cancer Center, Fred Hirsch, MD, PhD, “The study is retrospective with several limitations but it gives a clear message about the risk of smoking among cancer survivors. Not surprisingly, the study showed a significant increased risk for a secondary cancer in smokers.

"However, more interesting is the result that recent quitters had 18 percent less risk for developing all subsequent primary cancers than current smokers, so smoking cessation is important also for cancer survivors," said Dr. Hirsch.

“A smoking cessation program should be implemented among cancer survivors who smoke, and the patients should be carefully informed about the higher risk for a secondary cancer if they continue smoking,” Dr. Hirsch recommended.

The results of this study were published online July 25 in the Annals of Oncology.

The study was funded by grants from the Japanese Ministry of Health, Labour and Welfare and the Osaka Cancer Society. The authors declared no conflicts of interest.

Review Date: 
August 8, 2013