Archive for August, 2011

Smoking implicated in half of bladder cancers in women

Current cigarette smokers have a higher risk of bladder cancer than previously reported, and the risk in women is now comparable to that in men, according to a study by scientists from the National Cancer Institute (NCI), part of the National Institutes of Health. The report was published on Aug. 16, 2011, in the Journal of the American Medical Association.

This latest study uses data from over 450,000 participants in the NIH-AARP Diet and Health Study, a questionnaire-based study that was initiated in 1995, with follow-up through the end of 2006.

Female Bladder Cancer Link

While previous studies showed that only 20 to 30 percent of bladder cancer cases in women were caused by smoking, these new data indicate that smoking is responsible for about half of female bladder cancer cases – similar to the proportion found in men in current and previous studies. The increase in the proportion of smoking-attributable bladder cancer cases among women may be a result of the increased prevalence of smoking by women, so that men and women are about equally likely to smoke, as observed in the current study and in the U.S. population overall, according to surveillance by the CDC. The majority of the earlier studies were conducted at time periods or in geographic regions where smoking was much less common among women.

The researchers found that the amount of risk brought on by smoking, called excess risk, was higher in this study than in previously reported. “Current smokers in our study had a fourfold excess risk of developing bladder cancer, compared to a threefold excess risk in previous studies. The stronger association between smoking and bladder cancer is possibly due to changes in cigarette composition or smoking habits over the years,” said study author Neal Freedman, Ph.D., in NCI’s Division of Cancer Epidemiology and Genetics (DCEG). “Incidence rates of bladder cancer in the United States have been relatively stable over the past 30 years, despite the fact that smoking rates have decreased overall. The higher risk, as compared to studies reported in the mid-to-late 1990s, may explain why bladder cancer rates haven’t declined.”

Increase in Carcinogens

Although there have been reductions in the concentrations of tar and nicotine in cigarette smoke, there have been apparent increases in the concentrations of certain carcinogens associated with bladder cancer. A 2009 NCI/DCEG study was the first to suggest a higher risk for smoking-induced bladder cancer than previously reported. That report, based on data from the New England Bladder Cancer Study, found that the association between cigarette smoking and risk of bladder cancer appeared to be stronger than it was in the mid-1990s. The results of the new study confirm the 2009 report.

In the current study, former smokers were twice as likely to develop bladder cancer as never smokers, and current smokers were four times more likely than those who never smoked. As with many other smoking-related cancers, smoking cessation was associated with reduced bladder cancer risk. Participants who had been smoke-free for at least 10 years had a lower incidence of bladder cancer compared to those who quit for shorter periods of time or who still smoked.

20 Percent Still Smoke

“Our findings provide additional evidence of the importance of preventing smoking initiation and promoting cessation for both men and women,” said senior author Christian Abnet, Ph.D., also from DCEG. “Although the prevalence of cigarette smoking has declined, about 20 percent of the U.S. adult population continues to smoke.”

Even though smoking carries the same risk for men and women, men are still about four times more likely to be diagnosed with bladder cancer. These results, as well as those from previous studies, suggest that difference in smoking rates explain only part of the higher incidence rates in American men. The researchers suggest that occupational exposures, as well as physiologic differences, may contribute to the gender disparity.

In 2011, approximately 69,250 people will be diagnosed with bladder cancer in the United States, and 14,990 will die from the disease.

August 20th, 2011  in Tobacco No Comments »

Early morning smokers have increased risk of cancer

Two new studies have found that smokers who tend to take their first cigarette soon after they wake up in the morning may have a higher risk of developing lung and head and neck cancers than smokers who refrain from lighting up right away. Published early online in Cancer, a peer-reviewed journal of the American Cancer Society, the results may help identify smokers who have an especially high risk of developing cancer and would benefit from targeted smoking interventions to reduce their risk.

Cigarette smoking increases one’s likelihood of developing various types of cancers. But why do only some smokers get cancer? Joshua Muscat, PhD, of the Penn State College of Medicine in Hershey, and his colleagues investigated whether nicotine dependence as characterized by the time to first cigarette after waking affects smokers’ risk of lung and head and neck cancers independent of cigarette smoking frequency and duration.

More Likely to Develop Cancer

The lung cancer analysis included 4,775 lung cancer cases and 2,835 controls, all of whom were regular cigarette smokers. Compared with individuals who smoked more than 60 minutes after waking, individuals who smoked 31 to 60 minutes after waking were 1.31 times as likely to develop lung cancer, and those who smoked within 30 minutes were 1.79 times as likely to develop lung cancer.

The head and neck cancer analysis included 1,055 head and neck cancer cases and 795 controls, all with a history of cigarette smoking. Compared with individuals who smoked more than 60 minutes after waking, individuals who smoked 31 to 60 minutes after waking were 1.42 times as likely to develop head and neck cancer, and those who smoked within 30 minutes were 1.59 times as likely to develop head and neck cancer.

Higher Levels of Nicotine

These findings indicate that the need to smoke right after waking in the morning may increase smokers’ likelihood of getting cancer. “These smokers have higher levels of nicotine and possibly other tobacco toxins in their body, and they may be more addicted than smokers who refrain from smoking for a half hour or more,” said Dr. Muscat. “It may be a combination of genetic and personal factors that cause a higher dependence to nicotine.”

According to the authors, because smokers who light up first thing in the morning are a group that is at high risk of developing cancer, they would benefit from targeted smoking cessation programs. Such interventions could help reduce tobacco’s negative health effects as well as the costs associated with its use.

August 9th, 2011  in Tobacco No Comments »