Scientists Help ID New Cancer-Causing Agent in Tobacco Smoke

Organic compounds known as ‘aldehydes’ are primary source of damage to DNA and also suppress its ability to repair that damage

When it comes to cancer caused by cigarette smoke, experts may have misplaced the bulk of the blame.

According to a new study, scientists at NYU School of Medicine and Rutgers University have found that chemicals called aldehydes — present in tobacco smoke in high quantities — are the primary cause of damage to DNA and suppress its ability to repair damage. And ongoing, related work at Rutgers suggests consumption of certain healthy foods may help reduce the impact of these aldehydes.

Breakdown in a person’s DNA, or genetic code, is a major cause of cancer, according to the study; tobacco smoke has been linked to more than 80 percent of lung cancers and half of bladder cancers.

While smoking rates have declined to less than 14 percent of Garden State adults, each year roughly 2,500 residents are diagnosed with bladder cancer and nearly 6,000 with lung cancer, according to federal data.

Shifting scientific focus

In the past, researchers had focused on certain hydrocarbons and nitrosamines — organic compounds that are known carcinogens — present in cigarette smoke as the link to cancer. But the study suggests that while these chemicals are carcinogenic, they did not result in the same level of DNA harm as the aldehydes, which are also present in some foods in far lower levels.

Chung S. Yang
The study by Moon-shong Tang, an environmental medicine and pathology professor at NYU, and co-author Chung S. Yang, a distinguished professor of pharmacy at Rutgers University and director of the university’s Center for Cancer Prevention Research, was published online Tuesday in the Proceedings of the National Academy of Sciences.

The findings suggest that instead of focusing only on hydrocarbons and nitrosamines, researchers must also consider the impact of aldehydes. “Our findings provide the correct targets for both therapy and prevention of tobacco smoke-induced cancer,” Tang said.

The scientists hope their work will help generate better methods to assess cancer risks, as well as ways to reduce the damage caused by tobacco smoke. That’s where work by Yang and his Rutgers colleagues comes in. They are looking at how green tea and other beverages, fruits and some vegetables, can reduce these aldehydes from the body, cutting the risk for cancer and other diseases.

“In theory, this may help reduce the aldehydes generated through cigarette smoking,” Yang said, “and a lot of other compounds from our diet could do the same.”

‘Practical implications’ for preventing disease

The ability to reduce the impact of reactive aldehydes could have a “large practical implication in the prevention of disease,” Yang added, but he stressed that nothing is more effective in reducing cancer risk than quitting smoking.

The research echoes findings published two years ago in JAMA Oncology by scientists at the M.D. Anderson Cancer Center at Cooper, in Camden. They found that nearly half of all cancers could be prevented in the United States if people quit smoking, reduced their alcohol intake, lost weight, got more exercise, and ate healthier food — factors they found reduced the rate of cell mutations caused by breakdowns in DNA.

The organic compounds known as aldehydes can also be found in trace amounts in certain baked or fried foods, Yang said, since they are a common result of the chemical reactions that take place when fats or meat gristle is heated to a certain point. In fact, he said studies in China have shown higher levels of aldehydes in individuals who frequently cook over a wok, which heats oil to an extremely high temperature, especially in poorly ventilated homes.

“Aldehydes exist in many places in small quantities,” Yang said. “It’s the quantity that counts,” he added, saying that the level in food does not present much of a concern, “whereas in cigarette (smoke), it’s a very high concentration.”

While the study focused on cigarettes, Yang said in theory the process of heating oils — generally infused with tobacco or other substances — in a smokeless device, or vape pen, could also generate aldehydes, but he has not seen data on this.