Low Cholesterol Reduces Risk of High-Grade Prostate
Cancer; Does Not Promote Any Cancer
Lower total cholesterol may be caused by
undiagnosed cancer; higher levels of 'good cholesterol' (HDL) seem to be
protective from all cancers
Nov. 4, 2009 - A pair of studies in
Cancer
Epidemiology, Biomarkers & Prevention, lay to rest the decades-long
concern that lower total cholesterol may lead to cancer, and, in fact,
lower cholesterol may reduce the risk of high-grade prostate cancer.
Demetrius Albanes, M.D., a senior investigator at
the National Cancer Institute, said early studies suggested that low
cholesterol could increase the risk of certain types of cancer.
MIRP, especially with robotic assistance, increased from 1% to 40% of radical prostatectomies from 2001 to
2006,despite limited data on outcomes and costs
"Our study affirms that lower total cholesterol may
be caused by undiagnosed cancer. In terms of public health message, we
found that higher levels of 'good cholesterol' (HDL) seem to be
protective for all cancers, which is in line with recommendations for
cardiovascular health," said Albanes.
The researchers observed 29,093 men from the Alpha-Tocopheral,
Beta-Carotene Cancer Prevention Study cohort for 18 years, making it the
largest and longest study of its kind. In that follow-up period, they
noted 7,545 cancer cases.
Low total cholesterol blood levels were associated
with an 18 percent higher risk of cancer overall, similar to the
increases seen in previous studies, but this risk disappeared when the
researchers excluded cases that occurred in the early years after the
original blood draw.
This finding suggests that the low total
cholesterol levels did not cause cancer, but rather were the result of
underlying cancer, said Albanes. Higher levels of HDL cholesterol were
associated with a 14 percent decreased risk of cancer even after
excluding nine years of early cases.
In an accompanying study (see below) that looked
specifically at risk for high-grade prostate cancer, Elizabeth Platz,
Sc.D., M.P.H., associate professor in the Department of Epidemiology at
the Johns Hopkins Bloomberg School of Public Health and co-director of
the Cancer Prevention and Control Program at the Sidney Kimmel
Comprehensive Cancer Center at the Johns Hopkins University, found a
link between low cholesterol and decreased risk of high-grade prostate
cancer among 5,586 men older than 55 years.
Specifically, if men had total cholesterol of less
than 200 mg/dL they had a 59 percent reduced risk of high-grade prostate
cancer, defined as a Gleason score eight to 10. No association was seen
for prostate cancer overall or for prostate cancer with a lower Gleason
score. Platz said that the study supports another benefit of keeping
cholesterol low among men in this age group.
"High-grade prostate cancer is less common than
prostate cancer overall, but it is a subset of prostate cancer that is
more likely to progress," said Platz.
Role of Statins
Discussion of the benefits of lower cholesterol
inevitably leads to the discussion of the role of statins, which have
produced one of the great public health success stories of the past few
decades as cholesterol and, subsequently, heart disease rates have both
fallen.
Statins have been enormous money makers for their industry
manufacturers and with two already off patent, and the largest seller,
Lipitor scheduled to go off patent next year, researchers did leave open
the possibility that industry leaders may seek a new indication for
these blockbuster drugs.
"Until there is evidence from randomized trials,
men should not take statins in order to prevent high-grade prostate
cancer," said Eric Jacobs, Ph.D., strategic director of
pharmacoepidemiology at the American Cancer Society. Jacobs, who wrote
an accompanying editorial in the Cancer Epidemiology, Biomarkers &
Prevention issue. He said a randomized trial among men without prostate
cancer would need to be very large and might not be feasible.
"One possibility, however, would be a randomized
trial among early stage prostate cancer patients opting for surveillance
rather than immediate treatment, to see if statins could lower risk of
prostate cancer progression," Jacobs said.
John Hopkins Study
Low cholesterol may shrink risk for high-grade
prostate cancer
Men with lower cholesterol are less likely than
those with higher levels to develop high-grade prostate cancer - an
aggressive form of the disease with a poorer prognosis, according to
results of a Johns Hopkins collaborative study.
In a prospective study of more than 5,000 U.S. men,
epidemiologists say they now have evidence that having lower levels of
heart-clogging fat may cut a man's risk of this form of cancer by nearly
60 percent.
"For many reasons, we know that it's good to have a
cholesterol level within the normal range," says Elizabeth Platz, Sc.D.,
M.P.H., associate professor at the Johns Hopkins Bloomberg School of
Public Health and co-director of the cancer prevention and control
program at the Johns Hopkins Kimmel Cancer Center. "Now, we have more
evidence that among the benefits of low cholesterol may be a lower risk
for potentially deadly prostate cancers."
Normal range is defined as less than 200 mg/dL
(milligrams per deciliter of blood) of total cholesterol.
Platz and her colleagues found similar results in a
study first published in 2008, and in 2006, she linked use of
cholesterol-lowering statin drugs to lower risk of advanced prostate
cancer.
For the current study, Platz, members of the
Southwest Oncology Group, and other collaborators analyzed data from
5,586 men aged 55 and older enrolled in the Prostate Cancer Prevention
Trial from 1993 to 1996. Some 1,251 men were diagnosed with prostate
cancer during the study period.
Men with cholesterol levels lower than 200 mg/dL
had a 59 percent lower risk of developing high-grade prostate cancers,
which tend to grow and spread rapidly. High-grade cancers are identified
by a pathological ranking called the Gleason score. Scores at the
highest end of the scale, between eight and 10, indicate cancers
considered the most worrisome to pathologists who examine samples of the
diseased prostate under the microscope.
In Platz's study, cholesterol levels had no
significant effect on the entire spectrum of prostate cancer incidence,
only those that were high-grade, she says.
Platz cautions that, while the group took into
account factors that could bias the results, such as smoking history,
weight, family history of prostate cancer, and dietary cholesterol,
other things could have affected their results. One example is whether
men in the study were taking cholesterol-lowering drugs at the time of
the blood collections, a data point the researchers expect to analyze
soon.
Results of the current study are expected to be
published online Nov. 3 in the journal Cancer Epidemiology, Biomarkers &
Prevention. Also in the journal is an accompanying paper from the
National Cancer Institute showing that lower cholesterol in men
conferred a 15 percent decrease in overall cancer cases.
"Cholesterol may affect cancer cells at a level
where it influences key signaling pathways controlling cell survival,"
says Platz. "Cancer cells use these survival pathways to evade the
normal cycle of cell life and death."
She says that targeting cholesterol metabolism may
be one route to treating and preventing the disease, but this remains to
be tested.
Funding for the study was provided by the National
Cancer Institute.
Authors of the study include Cathee Till, Phyllis
J. Goodman, Marian L. Neuhouser and Alan R. Kristal from the Fred
Hutchinson Cancer Research Center; Howard L. Parnes, William D. Figg,
and Demetrius Albanes from the National Cancer Institute; Eric A. Klein
from the Cleveland Clinic; and Ian M. Thompson Jr., from the University
of Texas Health Sciences Center.
Sarcosine is better indicator of advancing disease
than traditional prostate specific antigen test (PSA); it is detected in
urine, researchers hopeful simple urine test can be used
Nov. 4, 2009 - A pair of studies in
Cancer
Epidemiology, Biomarkers & Prevention, lay to rest the decades-long
concern that lower total cholesterol may lead to cancer, and, in fact,
lower cholesterol may reduce the risk of high-grade prostate cancer. 
