Biological
Diversity Found in Ovarian Cancer Complicates Quest for Effective
Screening
Ovarian cancer has
been regarded as a single disease: now studies show two distinct
subtypes, a slow-growing and a more aggressive variety
Dec.
13, 2010 The frustration with the lack of solid, meaningful way to
screen women for ovarian cancer will apparently continue. New research
confirms annual screening is likely to result in only a modest reduction
in mortality from the disease and one of the reasons for the lack of
success is the conclusion that there are two subtypes of this cancer
one much more aggressive than the other.
Ovarian cancer
is a relatively rare disease that often progresses with few symptoms
until it is too late for potentially curative treatments. Also, elevated
values of the most commonly used biomarker used in screening, CA125, are
also related to other disorders, complicating screening results.
NEJM editorial says PARP inhibitors may point to a
new direction for anticancer drugs
Patricia
Buckles, after 29-year battle with breast cancer, says the
cancer disappeared after treatment with PARP inhibitors. View
the NBC News report by Brian Williams. Video link in story. - June 25, 2009
See links below news story to
recent research on ovarian cancer.
A computer-based
model of the progression of ovarian cancer from early to late stages was
recently designed at the Duke University Medical Center in Durham. The
model, which takes into account the fact that certain ovarian cancers
are slow growing while others grow more quickly, can test the
effectiveness of screening strategies for reducing the number of deaths
from ovarian cancer.
Scientists at
the Duke Cancer Institute say that incorporating the latest information
about the biological diversity of ovarian cancer appears to lessen the
potential value of screening even further.
"I feel that
what this and other studies are telling us is that we will have to do a
whole lot more than screening to protect women from this terrible
disease," said Laura Havrilesky, MD, an associate professor of
gynecologic oncology at Duke and the lead author of the study appearing
in the journal CANCER.
"We need to work
harder to find better approaches to screening and also consider the
potential value of preventive strategies."
About
Ovarian Cancer
Ovarian cancer usually happens
in women over age 50, but it can also affect younger women. Its
cause is unknown. Ovarian cancer is hard to detect early.
The sooner ovarian cancer is
found and treated, the better your chance for recovery. Many
times, women with ovarian cancer have no symptoms or just mild
symptoms until the disease is in an advanced stage and hard to
treat.
Symptoms may include:
● Heavy feeling in pelvis
● Pain in lower abdomen
● Bleeding from the vagina
● Weight gain or loss
● Abnormal periods
● Unexplained back pain that gets worse
● Gas, nausea, vomiting, or loss of appetite
Treatment is usually surgery
followed by treatment with medicines called chemotherapy.
Each year, about 22,000 women in the United
States are diagnosed with ovarian cancer. The symptoms of
ovarian cancer are often common and vague, which makes it
difficult to diagnose.
There are more than 30 different types of
ovarian tumors, which are categorized according to the cell
type. Some are benign (noncancerous) and do not spread beyond
the ovary. Malignant (cancerous) tumors can spread to other
parts of the body.
Currently, there is no effective early
detection method for ovarian cancer. It is usually diagnosed in
advanced stages, and only about half of women survive longer
than five years after diagnosis. For the 25% of ovarian cancers
that are found early, the five-year survival rate is greater
than 90%.
Studies have shown that prognosis and
survival depend largely on how much tumor is left at the time of
initial surgery. Patients who have no remaining tumor or with
nodules less than one centimeter in diameter have the best
chance for cure and long-term survival.
More at MD Anderson
Until recently,
ovarian cancer has been regarded as a single disease. But studies at
Duke and elsewhere have shown that it has at least two distinct
subtypes, a slow-growing, indolent form, which takes months to years to
move into an advanced stage, and a more aggressive variety driven by key
gene mutations that gallops through stages I and II in about half that
time.
Havrileskys
research team used information in the SEER database to create a decision
model for screening for ovarian cancer. The SEER database, maintained by
the National Institutes of Health, includes information on cancer
incidence, prevalence and survival in over a quarter of the U.S.
population and breaks out ovarian cancer by type.
They then
validated the model using early data from a real-life study, the U.K.
Collaborative Trial of Ovarian Cancer Screening (UKCTOCS), a large,
randomized trial that is using CA125 values and ultrasound to screen a
general population of post-menopausal women for ovarian cancer.
In
conceptualizing ovarian cancer as a single disease, the model predicted
that screening women over the age of 50 in the United States could
potentially lower cancer deaths by about 15 percent. But incorporating
the two subtype concept, the model predicted deaths would fall by only
11 percent.
Havrilesky says
it just makes sense: Screening is more likely to pick up a greater
number of slow-growing, as opposed to fast-growing tumors, because
indolent cancers remain in a more treatable early stage almost twice as
long as their more virulent counterparts.
"But catching
and successfully treating the slower-growing cancers isn't going to do
as much to reduce deaths from ovarian cancer as much as catching the
more lethal tumors would do," she added.
"If we assume
ovarian cancers grow and spread at different rates, the best screening
strategy available will only reduce the number of women dying from this
cancer by 11 percent. This is partially because the slower growing
cancers are more likely to be caught by a screening test," said Dr.
Havrilesky.
The findings
support the commonly held clinical impression that many early stage
ovarian cancers are destined to remain in the early stages for some
time, while advanced stage cancers have likely spread rapidly.
More sensitive
screening tests will be needed to significantly reduce deaths attributed
to ovarian cancer. For now, other measures that focus on prevention and
treatment should be pursued to save women's lives.
In an
accompanying editorial, Patricia Hartge, MA, ScD, a senior investigator
in the Division of Cancer Epidemiology and Genetics at the National
Cancer Institute, notes the modest benefit of screening for a general
population, but says that screening for women at higher risk of ovarian
cancer those who carry mutations known to be related to the disease or
who have a family history of it presents a more hopeful picture.
But Havrilesky
is not so sure. She says screening in even the highest risk population
has not yet been proven successful and says other options are under
study that may hold merit.
'We know that
women who take oral contraceptives have a reduced risk of ovarian
cancer, and the Duke Evidence-Based Practice Center is currently doing a
systematic review and model to determine if this might be a reasonable
approach for some women."
The research was
supported by a grant from the American Board of Obstetrics and
Gynecology/American Association of Obstetricians and Gynecologists
Foundation.
Colleagues from
Duke who contributed to the study include senior author Evan Myers,
Gillian Sanders, Junzo Chino, Andrew Berchuck and Jeffrey Marks.
Co-author Shalini Kulasingam is from the University of Minnesota.
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Keep up with the latest news for senior citizens, baby
boomers
Dec.
13, 2010 The frustration with the lack of solid, meaningful way to
screen women for ovarian cancer will apparently continue. New research
confirms annual screening is likely to result in only a modest reduction
in mortality from the disease and one of the reasons for the lack of
success is the conclusion that there are two subtypes of this cancer
one much more aggressive than the other.