Obesity, Insulin Level Impact Prostate Cancer Survival

By Amanda Gardner
06 oct 2008-- 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."

Better Prostate Cancer Survival for Men Taking Statins

By Ed EdelsonHealthDay ReporterWed Oct 31, 7:00 PM ET
WEDNESDAY, Oct. 31 (HealthDay News) -- Men who were taking statins to lower their cholesterol had a 10 percent greater chance of being cured of prostate cancer by radiation therapy 10 years after diagnosis, a new study finds.
It's an "intriguing and very interesting finding," but falls short of supporting statin use for all prostate cancer patients, said study author Dr. Michael J. Zelefsky, a professor of radiation oncology at Memorial Sloan-Kettering Cancer Center in New York City. He was to deliver the results Wednesday at the American Society for Therapeutic Radiology and Oncology annual meeting, in Los Angeles.
"But I would encourage men to see their internist and get on the medications if their blood cholesterol warranted it," he said.
Zelefsky reported on 871 men given radiation therapy for prostate cancer between 1995 and 2000. The five-year relapse-free survival rate for the 168 men taking statins was 91 percent while the 10-year survival rate was 76 percent. That compares to 81 percent and 66 percent, respectively, for those not taking the drugs.
"There have been some reports of a lower risk of developing prostate cancer for those men who have been on statins," Zelefsky said, but the possible mechanisms by which the drugs might help prevent the disease or cure it are unknown.
"There was a suggestion made of a possible added benefit by an interaction between the drug and radiation," he said. "Or does it have its own independent effect? That is possible as well."
Zelefsky added that this study, and others suggesting a beneficial effect of statins on prostate cancer, "give fuel to stimulate what is the only way to absolutely corroborate such an effect, in a randomized, controlled trial."
Dr. Eric Horwitz, clinical director of radiation oncology at the Fox Chase Cancer Center in Philadelphia, said he agreed with Zelefsky's call for a tightly monitored clinical trial. "There has been great success in running these large tests, and I'm sure it can be done."
As it is, many men diagnosed with prostate cancer are already taking statins, and there is no reason for them to stop, Horwitz said. "This report is reassuring because of the overlap," he noted.
Two recent reports have linked statin use with a lower risk of developing prostate cancer. One study, from the University of Alabama, Birmingham, found a decline in prostate cancer death rates that was most notable among white men who used statins.
Another study, from Duke University Medical Center, found lower blood levels of prostate-specific antigen, a potential marker of the cancer, among men taking statins.
A study on statin use in prostate cancer prevention or treatment should center on men at higher risk, Zelefsky said -- "Older men with a family history."
There is "no significant downside" to statin use in such studies because the drugs have a low rate of adverse side effects, he said.
More information
For more on prostate cancer, visit the U.S. National Cancer Institute.

Most Asian Men Have Better Prostate Cancer Survival Rates

By Steven ReinbergHealthDay Reporter 40 minutes ago
MONDAY, Aug. 13 (HealthDay News) -- Your prognosis for surviving prostate cancer may depend on your racial and ethnic background, a new study suggests.
Asian men have better survival rates than white males, while South Asians have the worst survival rates, according to results of a study of men living in California.
"Nearly all Asians do far better when they get prostate cancer," said study lead author Dr. Anthony Robbins, of the California Cancer Registry in Sacramento. "But Indian men didn't do as well as other Asian men, and they did worse than all other men, including blacks and whites," he added.
The reasons for these racial and ethnic differences in prostate cancer survival aren't known, Robbins said, adding, "We just couldn't explain it."
Not only couldn't the researchers explain the finding, they were left with an apparent paradox. The Asian men were usually older and had more advanced disease at the time of diagnosis, Robbins said. "Based on their risk factors, you would think they were going to do worse," he said.
In the study, Robbins and his colleagues collected data on 116,916 men (108,076 whites and 8,840 Asians from the six largest represented Asian ethnicities -- Chinese, Filipino, Japanese, Korean, South Asian, and Vietnamese) diagnosed with prostate cancer. The researchers compared prognostic factors and survival rates among the men.
The researchers found that for Asians, risk profiles were worse compared with whites. For example, Asians were more likely to have more advanced disease and use non-curative therapies. But, for Asians -- except for South Asians -- survival rates were equal to or better than rates for whites.
Japanese-American men were 34 percent less likely to die from prostate cancer compared with whites. But South Asian men -- those from India, Pakistan, Bangladesh, Sri Lanka, Nepal, and Bhutan -- were 40 percent more likely to die from the disease, Robbins said.
The study was published online Monday in the journal Cancer.
Some of the factors that may influence the findings include diet, exercise and genetics, Robbins speculated.
"Doctors that are seeing patients for prostate cancer need to be aware that these differences can be used as factors in planning the patient's treatment and telling the patient what their survival might be," Robbins said.
Dr. Durado Brooks, director of prostate and colorectal cancer at the American Cancer Society, thinks this study demonstrates the need to better understand how different racial and ethnic groups respond to diseases.
"This study points out the potential misleading conclusions we can come to when we use these large groups to lump different subpopulations into," he said.
"If you lump in the South Asian subgroup with other Asians, as is traditionally done, you totally miss the fact that these folks have a strikingly higher chance of dying from prostate cancer," Brooks said.
Brooks said the study finding can provide a basis for research to try to understand why these differences exist between populations.
Prostate cancer is the most common type of cancer to strike American men, other than skin cancer, according to the American Cancer Society, which estimates there will be about 218,890 new cases of prostate cancer in the United States in 2007, and about 27,050 men will die of the disease. Prostate cancer is the second leading cause of cancer death in males. While one in six men will get prostate cancer during his lifetime, only one man in 34 will die of the disease. The death rate for prostate cancer is declining, due in large part to earlier diagnoses, the society said.
Another paper in the same issue of the journal also found racial differences among women who survive breast cancer; with black women having poorer survival regardless of the stage of the disease.
It is known that black women had larger tumors and are more likely to have invasive breast cancer. But the study, lead by Dr. Alfred Neugut from Columbia University Medical Center and Russell McBride from Mailman School of Public Health, found that mortality among black women was up to 56 percent higher than whites.
Neugut's team says that the disparities in survival were surprising and suggest that non-clinical factors, such as access to and quality of care, may play a part.
More information
For more on prostate cancer, visit the American Cancer Society