- SUNDAY, Oct. 5 (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.