Experts Highlight Inroads to Preventing Cancer

(HealthDay News) -- Scientists looking at everyday factors that influence cancer risk are finding important new clues that could affect cancer prevention strategies.

"Many of us believe that prevention is better than trying to identify drugs for people after they get cancer," said Dr. Peter Shields, deputy director of the Lombardi Comprehensive Cancer Center and interim chairman of the Department of Medicine at Georgetown University Medical Center in Washington, D.C. "As we understand risk factors better, it may be possible to personalize cancer prevention."

Shields moderated a Monday teleconference highlighting cancer prevention-related findings that are being presented at the annual meeting of the American Association for Cancer Research, in Denver.

One study found that two common gene variants do not protect individuals from the ill effects of smoking.

In the study, smoking boosted the odds for the two most common types of colorectal polyps: adenomas and hyperplastic polyps, although the association was stronger in the latter.

People who had smoked a pack of cigarettes a day for a year had a 68 percent increased risk for adenomas but a 238 percent increased risk for hyperplastic polyps. Those still smoking had the same risk for adenomas as former smokers but a more than threefold increased risk for the second type of polyp.

Polyps can be precursors to colon cancer, but if they're detected early, the disease can often be prevented.

There was also a slight though not statistically significant risk from "charred" (well done) meat.

"Susceptibility to smoking did not vary by this gene, and everyone needs to be concerned [about the risk of smoking]," said Andrea N. Burnett-Hartman, a doctoral student at the Fred Hutchinson Cancer Research Center in Seattle.

"This gene is not going to protect you from the carcinogenic effects of smoking, at least in colorectal tissue," she said. In terms of meat consumption, she added that "everything in moderation" remains a good rule.

Another study found that specific genetic variations in the cox-1 and cox-2 genes indicate different risks for colorectal cancer. This might help determine who would benefit from the cancer-prevention benefits of nonsteroidal anti-inflammatory drugs (NSAIDs).

Although NSAIDs, including aspirin and cox-2 inhibitors, have been shown to reduce the risk of colorectal cancer, that benefit may be nullified by an increased risk of heart disease seen in some cox-2 inhibitors such as Vioxx, which was removed from the market.

Other findings being presented at the society's meeting include:

• A tool that looks simultaneously at several genetic variants and family history might more accurately predict who is at risk for prostate cancer and who could benefit from more aggressive prevention efforts. Men who had at least 15 of the gene variants included in the tool were found to have a 34 percent increased risk of developing prostate cancer in a 20-year span, or 45 percent increased risk if they had a family history of the disease. But without the combination of genetic information, their risk would have been estimated at only 13 percent.
• Rats born to mothers who had been given folic acid supplementation during and after pregnancy were found to have experienced changes in DNA methylation in both the liver and the colon. DNA methylation is a process whereby genes can be turned off or on. Folic acid is recommended before and during pregnancy to prevent neural tube defects in babies. Folic acid intake in North America has soared since these recommendations were implemented in 1998.
• Abnormal collections of cells were found in the blood of 38 percent of people with chronic lymphocytic leukemia (CLL) as early as 10 years before their diagnosis -- something that could be a clue in the so-far fruitless search for causes of the disease. "Apparently, these cells are cranking out proteins years before people get CLL," said Dr. Neil Caporaso, a section chief at the U.S. National Cancer Institute. "We can try to understand what causes people to get these abnormalities and, more importantly, what causes somebody to progress from having relatively benign protein abnormalities to developing leukemia. We can search for environmental agents and genes that could cause this next step."

More information
The American Cancer Society has more on preventing cancer.

Obesity, Insulin Level Impact Prostate Cancer Survival

(HealthDay News) -- Men who are overweight and who have high insulin levels when they are diagnosed with prostate cancer may be more likely to die from the disease, research shows.

This striking finding, published early online and expected to be in the November issue of The Lancet Oncology, is yet more reason to continue fighting the battle of the bulge, experts say.

"I don't want to be sensationalist, but obesity effects and the insulin effects are so big that I think if you had to choose between being thin and having a low insulin level or having access to the best chemotherapy, you would be more likely to survive without chemotherapy," said study senior author Dr. Michael Pollak, professor of oncology at McGill University in Montreal, Quebec, Canada.

"Tens of thousands of men are taking chemotherapy for prostate cancer -- as they should, because it is a good treatment. Doing so is actually helping," he said. "But potentially, dealing with insulin, obesity may one day be of more benefit."

The findings also have scientific import, giving researchers a clue that could lead to new prevention and treatment strategies.

Experts have long known that androgens, or male hormones, play a critical role in spurring prostate cancer.

In fact, these cancers are often treated with approaches that deprive the tumors of testosterone.

Smaller reports have suggested that obese patients with prostate cancer have a worse prognosis than patients of regular weight, though weight hasn't been related to actually developing a malignancy.

"We found in a large sample that obesity has a very important influence on prostate cancer outcome," Pollak said. "Then the question becomes, why would obesity make the outcome worse?"

Pollak and his colleagues looked at information on more than 2,500 men who had been followed for 24 years as part of the Physicians' Health Study. Information on body mass index (BMI) was available for all of these men, while information on C-peptide concentration (a marker of insulin levels in the blood) was available for 827 men.

Overweight men (those with a BMI of 25 to 29) had a 47 percent higher risk of dying from prostate cancer, while obese men (BMI of 30 or over) were more than two-and-a-half times more likely to die of the disease, compared with men of healthy weight (BMI under 25).

Men with the highest C-peptide concentrations also had more than double the risk of dying from their cancer compared with men with the lowest levels, the study found.

Finally, men who had a BMI of more than 25 and high C-peptide concentrations had quadruple the risk of dying from their cancer compared with men who had lower BMIs and lower C-peptide levels, the researchers reported.

"This suggests that there may be a whole new story to tell, whereby not just androgens have something to do with cancer behavior, but also insulin," Pollak said.

The insulin hormone may be latching onto insulin receptors located on prostate cancer cells, he speculated.

Some pharmaceutical companies are already testing drug candidates that target insulin signaling, Pollak added.

And the findings could have broader implications for other cancers, said study lead author Dr. Jing Ma, of Harvard University's Channing Laboratory.

"The simple things are still the important things. Don't drink, don't smoke, exercise, and eat well," said Dr. Ganesh Palapattu, assistant professor of urology, pathology and oncology at the University of Rochester School of Medicine. "This is yet another piece of evidence suggesting that obesity is not a good thing for many reasons."

"Obesity is the second leading cause of cancer death in this country next to tobacco," emphasized Dr. Jay Brooks, chief of hematology/oncology at Ochsner Health System in Baton Rouge, La. "Two years ago, I would never have told my patients that obesity is increasing their risk of death from cancer. Today, I do."

More information
There's more on prostate cancer at the U.S. National Cancer Institute.