LOS ANGELES, Oct 21, 2004 /PRNewswire via COMTEX/ --
A just-published research study by
Urological Sciences Research Foundation may help explain a quandary that has
perplexed medical scientists for decades: why is prostate cancer so much more
common in the West than in Asia? Diet has long been chief suspect for the
difference. The new study compared dietary influences on prostate tissues of
Japanese men who spent their life in Japan vs. other Japanese men who spent
their life in the U.S. The Western diet, relatively rich in animal fat and
poor in soy, was found to exert
cancer-causing influences that could be traced directly into prostate tissues.
"This study is important because it's among the first to look directly at
tissues, in an attempt to link diet and cancer," commented Professor Alan
Partin of Johns Hopkins University. The side-by-side tissue comparison
appears in the October issue of the medical journal Urology and is the product
of a 5-year collaboration between U.S. and Japanese scientists.
Diet has long been thought to influence development of prostate (and
other) cancers that are common in Western countries and rare in Asia. As much
as a 10-fold greater occurrence of prostate cancer in the U.S., compared to
Japan and other Asian countries, has been observed. When Asian men migrate to
Western countries and adopt a Western lifestyle, the protection begins to
disappear within one generation.
Now a linkage between diet and cancer appears to be explained at the
tissue level. "Oxidative damage from saturated fat (in Western diet) and a
protective effect from soy phytoestrogens (in traditional Japanese diet) are
possible mechanisms," the authors write. The authors speculate that if
further research confirms these findings, "... dietary modification would
become an important public health issue and interest in nutrition-related
treatment methods might evolve."
"Cancer can be caused by both hereditary and environmental factors,"
according to principle author Leonard S. Marks, M.D., of UCLA and Urological
Sciences Research Foundation (USRF). Dr. Marks said, "We chose to study
prostate cancer in men with the same genetics (all of Japanese descent), but
with differing diets -- one Eastern and one Western -- to see if dietary
differences translate into differing tissue effects." And this does seem to
be the case.
The mechanism of cancerous change appears to be different, determined by
dietary influences on how fat is handled by the prostate tissues and how
certain enzyme systems known as caspases operate within the tissues. And
despite fundamental genetic homogeneity of the two groups, the genetic
material (DNA) in the prostate cells was different between the two groups,
suggesting the possibility of a gene-nutrient interaction.
The Japanese-American men in the study were all born in Los Angeles or
Hawaii and their body composition was measurably different from those native
Japanese men who had spent their lives in the Nagoya, Japan area. Tissue and
dietary data were gathered by Dr. Marks and colleagues in Los Angeles with the
help of L.A. urologists George Yamauchi and Yuichi Ito, and in Nagoya, Japan
by Dr. Munekado Kojima. Tissue studies were performed at Johns Hopkins
University and dietary studies at the UCLA Center for Human Nutrition.
The study was completed under the auspices of the UCLA Office for
Protection of Human Subjects and was supported by grants from The Prostate
Cancer Foundation of Santa Monica, CA and the Pardee Foundation of Midland,
MI. George Takei of Star Trek fame served as ombudsman to the Japanese-
American community in Los Angeles. The study was conceived and coordinated at
Urological Sciences Research Foundation (USRF) (http://www.usrf.org), a
non-profit research corporation (501c3) based in Culver City, CA.
http://www.usrf.org/japanese-american_cap/geolsmmuseum.jpeg . Touring the
Japanese-American National Museum in Los Angeles are George Takei (museum
founder and Star Trek's 'Mr. Sulu') and principle study author Leonard S.
Leonard S. Marks, M.D.
Phone: 310-559-9800 (24 hr)
SOURCE Urological Sciences Research Foundation
USRF Offices, +1-310-559-9800, or fax, +1-310-838-8910; or
Leonard S. Marks, M.D., firstname.lastname@example.org, for Urological Sciences Research
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