Gum Disease and Cancer Risk

dental exam oral cavity white male head and neck oropharynx

New data supports the need to further investigate an association between periodontal disease and cancer risk.

Background: Previous studies have found periodontal disease is a risk factor for breast, oral, and esophageal cancers. Case-control studies have shown a link between tooth loss and the risk for esophagus and stomach cancers.

The Study: Investigators examined periodontal disease information in 65,869 women ages 54 to 86 at 40 centers in the USA. Mean age 68 years. Most were non-Hispanic whites with some college education. Participants answered this question: “Has a dentist or dental hygienist ever told you that you had periodontal or gum disease?”

The Results: This large prospective cohort study shows that postmenopausal women with a history of periodontal disease, including those who have never smoked, are at significantly increased overall risk for cancer as well as site-specific cancers, including lung, breast, esophageal, gall bladder, and melanoma skin cancers.Although periodontal disease and cancer share important risk factors (such as increased risk with increasing age and increased in smokers), this study showed that after adjustment for age, the risk of periodontal disease history and cancer persists regardless of smoking history.

My Take: This study adds to a growing body of evidence from smaller studies that link periodontal disease to total cancer risk. Oral hygiene is important not only in preventing tooth loss, but may have important implications for prevention of systemic diseases, including cancer. I’m Dr. Michael Hunter.

Cancer Epidemiol Biomark Prev. Published online 01 Aug 2017.

Available Today: Your Breast Cancer app on Android (in Search, type Michael Hunter Your Breast Cancer … and voila!)

Do Antioxidants Promote Lung Cancer?

vitamin E antioxidants

A decades-old medical mystery – why antioxidants such as vitamin E and beta carotene seemed to accelerate the growth of early lung tumors in high-risk populations such as smokers, rather than protect them from cancer, as theory suggests – may have been solved, according to new research.

“Antioxidants allow cancer cells to escape cells’ own defense system” against tumors, biologist Per Lindahl of Sweden’s University of Gothenburg and a co-author of the study told reporters. That lets existing tumors, even those too small to be detected, proliferate uncontrollably. The findings imply that “taking extra antioxidants might be harmful and could speed up the growth of (any) tumors,” said biologist and co-author Martin Bergo of Gothenburg, adding, “If I had a patient with lung cancer, I would not recommend they take an antioxidant.”

The study did not examine whether antioxidants can also initiate lung cancer, rather than accelerate the growth of existing tumors. Nor did it examine whole foods naturally high in antioxidants. But it adds to a growing pile of research challenging the health benefits of taking vitamin supplements except in cases of malnutrition.

Last month, a review of dozens of studies found “no clear evidence of a beneficial effect of supplements” on heart disease, cancer or mortality. An accompanying editorial in the Annals of Internal Medicine warned that “beta carotene, vitamin E, and possibly high doses of vitamin A supplements are harmful,” while other antioxidants are “ineffective.”

The new antioxidant study “seems quite sound,” said Eliseo Guallar, professor of epidemiology at Johns Hopkins Bloomberg School of Public Health and a co-author of the editorial. “It’s unfortunate that the public has the idea that vitamin supplements are good and antioxidants are better.”

One concern about the new study is that the mice received doses of vitamin E at least four times, and as much as 50 times, Americans’ recommended daily intake, noted Duffy MacKay of the Council for Responsible Nutrition, the supplement industry trade group. Government data show that 90% of Americans have diets that contain less than the recommended intake of vitamin E, he said, calling the Swedish study “very interesting and hypothesis-generating,” but not one that should change behavior.

PROTECTING DNA

Of all the gaps between biological theory and medical reality, few are as stark as that involving antioxidants. In cells growing in the lab, antioxidants scavenge and disable free radicals, reactive chemicals produced during normal metabolism that can harm DNA and other components of cells. By the 1980s that had led to the idea that by protecting DNA from damage, antioxidants might prevent cancer and other disease and launched a bull market in antioxidants that continues unabated, with packages of cereal, granola bars, juice and more all touting their antioxidants and health magazines and television shows urging consumers to load up on them.

For the new study, the Gothenburg scientists gave vitamin E and a generic drug called N-acetylcysteine, both antioxidants, to mice with early lung cancer. The vitamin E doses were comparable to those in supplements; the doses of acetylcysteine, which is prescribed for chronic obstructive pulmonary disease (COPD) to reduce mucus, were relatively low.

The antioxidants caused a 2.8-fold increase in lung tumors, made the tumors more invasive and aggressive, and caused the mice to die twice as quickly – all compared to mice not given antioxidants.

When the antioxidants were added to human lung tumor cells in lab dishes, they also accelerated cancer growth. That result jibed with the many studies finding that “antioxidants do not protect against cancer in healthy people and may increase it” or promote it in those who already have cancer, said Bergo.

The significant advance in the study was pinpointing how this can be. What seems to happen is that antioxidants indeed decrease DNA damage, as expected. But the damage becomes so insignificant as to be undetectable by the cell. The cell therefore does not deploy its cancer-defense system, which is based on a protein called p53.

Ordinarily, if p53 detects significant DNA damage, such as from ultraviolet light, it kills the cell before it can become malignant. By allowing cancer cells to stay below the radar of p53, antioxidants allow tumors to thrive, the study found. The scientists stressed that the results do not pertain to foods such as fruits and vegetables that are naturally high in antioxidants.

As for people with COPD who are taking acetylcysteine, “we think that should be carefully evaluated,” Bergo said. Although the study investigated only lung cancer and two antioxidants, previous research suggests that other cancers can also be accelerated by antioxidants, Bergo said, and that other antioxidants have this effect.

The National Cancer Institute already advises cancer patients that antioxidant supplements “should be used with caution.”

The discovery of how antioxidants thwart cells’ innate cancer-fighting machinery might explain why a groundbreaking 1994 study found an 18% higher incidence of lung cancer among 29,133 male smokers who received beta carotene than those who did not. The result was so unexpected and unwelcome that the editorial in the journal where it was published tried to dismiss it as “an extreme play of chance.”

“It’s disappointing but not surprising that people’s beliefs are not modified by scientific evidence,” said Dr. Paul Marantz, an epidemiologist at Albert Einstein College of Medicine in New York. “People so want to believe there is a magic bullet out there.”

I’m Dr. Michael Hunter, and I recommend that we all eat whole fruits. Mix your colors! Orange! Blue! Red! There is more than vitamins there… Cheers!

The small print: The material presented herein is informational only, and is not designed to provide specific guidance for an individual. Please check with a valued health care provider with any questions or concerns. As for me, I am a Harvard- , Yale- and UPenn-educated radiation oncologist, and I practice in the Seattle, WA (USA) area. I feel genuinely privileged to be able to share with you. If you enjoyed today’s offering, please consider clicking the follow button at the bottom of this page.

Available now: Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Both can be found at the Apple Ibooks store. Coming Soon for iPad:  Understand Breast Cancer in 60 Minutes; Understand Colon Cancer in 60 Minute; Understand Colon Cancer in 60 Minutes; Understand Brain Glioma in 60 Minutes. Thank you.

References: http://bit.ly/1d8gb1s; http://www.medscape.com/viewarticle/819933