SAN FRANCISCO (Reuters) - Final proof that dietary components like green tea,
curry spice or wine can fight cancer in humans and not just laboratory test
tubes remains elusive, but researchers are full of hope for the unconventional
treatments.
"I believe that 50 years from now there
will be a sub-specialty of medicine called cancer prevention doctors," Dr. Allan
Conney, professor of cancer and leukemia at New Jersey's Rutgers University,
said on Wednesday.
"These doctors will be able to identify cancer risk factors for each
individual and, along with pharmacists, prescribe drugs, diet or lifestyle
changes." Speaking in San Francisco at a meeting of the American Association for
Cancer Research, Conney said studies now underway on the anti-cancer effects of
green tea, turmeric and other agents will eventually add years to the human life
span.
But he noted that the leap from testing these theories in the lab to testing
them in humans remains as difficult as ever. "Results of trials in humans have
been inconsistent. There is a need for much more carefully controlled studies,"
Conney said.
One solution is to measure the body's processing of a particular dietary
component, rather than rely on patients to report their actions, he suggested.
One study using this approach found that drinking green tea cuts in half the
chance of cancer of the stomach or esophagus in Chinese men at high risk for the
disease.
Several studies have suggested green tea might help ward off heart disease
and certain cancers, possibly due to potent antioxidant substances called
polyphenols, which are also found in foods like grapes and wine. Antioxidants
help protect the body from cell-damaging forms of oxygen that occur naturally in
the body and are believed to contribute to a range of diseases.
"This is the first human evidence that tea polyphenols reduce the risk of
esophageal cancer," said Dr. Can-Lan Sun, a researcher at the University of
Southern California in Los Angeles and the study's lead author.
GREEN TEA DOES NOT AFFECT ADVANCED PROSTATE CANCER
The study, which followed middle-aged or older men in Shanghai, China, for
between four and 12 years, found that men whose urine had high levels of a
particular tea polyphenol -- a measurement of tea consumption -- had a lower
risk of both stomach and esophagus cancers.
But another study, conducted at the Mayo Clinic in Rochester, Minnesota,
found that green tea was not effective as a treatment for men who already have
advanced prostate cancer. Only one patient of the 42 evaluated in the mid-stage
trial saw his cancer improve, and the response did not last.
After one month of treatment -- the study was designed to last four months --
many patients dropped out because their cancer got worse and because of
caffeine-related side effects.
Dr. Aminah Jatoi, lead investigator and assistant professor at the clinic's
oncology department, said the study used a high dose -- liquid tea concentrate
equivalent to 12 cups a day -- because the researchers did not want to be
accused of shortchanging these very sick patients.
Preliminary results from another study, this one in test tubes, showed that a
component of the popular Indian spice turmeric may also help fight cancer.
Researchers from Detroit's Henry Ford Health System found that the active
ingredient in turmeric, called curcumin, can boost the cancer-fighting power of
treatment with a naturally occurring molecule, called TRAIL, that helps kill
cancer cells.
Subhash Gautam, a researcher at the Henry Ford Health System, said the
combination treatment will next be tested in mice.
There is evidence that turmeric has anti-inflammatory and antioxidant
properties and it may work against cancer cells by sensitizing them to other
drugs, he said.
In another study, researchers at Germany's University of Ulm, found that
combining TRAIL with resveratrol, an antioxidant found in red wine, killed
cancer cells and slowed the growth of human tumors implanted in mice.
