Just
a Few Hostile Cells Fuel Breast Cancer Growth
Powerhouse
'factory' cells may be key targets for medications
Breast
cancer may contain a tiny minority of aggressive "stem" cells that can
give rise to entire new tumors, new research says.
As
few as 100 of these cells can allow the tumor to make copies of
itself, becoming a factory that makes all the other types of cells in
the original tumor, says the study, that appears in a recent issue of
the Proceedings of the National Academy of Sciences.
Their ability to regenerate is much like that of stem cells, researchers
say.
Even
tens of thousands of other types of cells in the same tumor did not
create more cancer, the study says.
"We're
really excited; we're extraordinarily excited," says study author Dr.
Michael F. Clarke, a professor of internal medicine at the University
of Michigan Medical School. By isolating these cells, they have narrowed
the field that therapies may one day target in the overall confusing
mix of cells in these tumors, he adds.
Detecting
Cells Could Lead to Earlier Diagnosis
Detecting
these cells could also lead to a way that will let physicians diagnose
the disease sooner, says Clarke. However, even though human cancer tissue
was used, the tests were done on mice, so a practical application for
their findings is still in the future, although Clarke says their research
might be useful for humans within five years.
"We're
three steps away [from developing a drug]," Clarke says. Next, researchers
will find out what pathways let these cells form tumors, then they will
find out where the pathways are and focus on them. The third step is
to develop medications to attack these pathways.
More
than 40,000 women die of breast cancer each year in the United States
and it is the most common type of cancer in women.
Other
scientists also see potential in this discovery.
This
is "a very intriguing study, which provides molecular identification
of particularly aggressive breast cancer cells and which suggests potential
new avenues for diagnosis and therapy," says Dr. Calvin Kuo, an assistant
professor of medicine at Stanford University.
The
Michigan research builds on a previous study that saw a similar effect
in a type of leukemia (blood cancer), but this is the first time these
"stem" cells have been found in a solid cancer, the researchers say.
Figuring
out how to tell the difference between the two kinds of cells took years
for Muhammad Al-Hajj, a postdoctoral fellow and a co-author of the study.
He and the team took tumor tissue from nine breast cancer patients,
and discovered that eight of them had the same protein "fingerprint"
on the surface of their cancer cells. The ninth had a biological variation
that made the separation of cell types difficult, says Clarke.
In
the remaining eight samples, the nasty "stem" cells had a pattern of
surface proteins where there was a lot of a type called CD44 and little
to none of a type called CD24. The researchers harvested cells showing
this pattern and injected them into mice. As few as 100 of these cells
caused tumors identical to the original to form, the researchers found.
Since
an aggressive subset of cells has been found in both blood and breast
cancers, the scientists think other types of cancer might be driven
by them, as well.
Always
consult your physician for more information.
Tamoxifen
Cuts Risk of Benign Breast Disease
Drug
reduces hyperplasia, fibrocystic disease by 28 percent
Tamoxifen,
the drug that has been shown to cut the risk of breast cancer in high-risk
women, also appears to reduce the incidence of noncancerous breast disease,
new research shows.
An
earlier trial, the Breast Cancer Prevention Trial,
part of the National Surgical Adjuvant Breast and Bowel Project
(NSABP), found that tamoxifen reduced the incidence of invasive
and noninvasive breast cancer by up to 50 percent.
In
the current trial, reported in a recent issue of the Journal
of the National Cancer Institute, the drug reduced the incidence
of benign breast disease, including fibrocystic disease and hyperplasia,
by 28 percent. It also resulted in fewer biopsies.
Tamoxifen
interferes with the activity of the hormone estrogen and is therefore
effective in breast cancers that are estrogen-receptor positive. Estrogen
receptors are also expressed in benign breast lesions, leading researchers
to believe that tamoxifen might also have an effect here.
Benign
breast disease can be a risk factor for later breast cancer.
Always
consult your physician for more information.
Online
Resources
American
Cancer Society
Breast
Cancer Prevention Trial
Journal
of the National Cancer Institute
National
Cancer Institute
National
Institutes of Health (NIH)
National
Surgical Adjuvant Breast and Bowel Project (NSABP)
Proceedings
of the National Academy of Sciences
|
March
2003
Powerhouse
'Factory' Cells May Be Key Targets for Medications
Detecting
Cells Could Lead to Earlier Diagnosis
Tamoxifen
Cuts Risk of Benign Breast Disease
Younger
Women With Family History Skip Mammograms
Online
Resources
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a St. John's Mercy Physician
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Other Breast Health News:
Younger
Women With Family History Skip Mammograms
New
research says fear may be the key factor
Younger
women with a family history of breast cancer are less likely than
others to get regular mammograms.
That
is the surprising finding of a new study that evaluated almost 30,000
women.
While
the study showed that educated Caucasian women with higher incomes
and insurance coverage are the most likely to get routine breast-cancer
screenings, it also showed that women in their 40s with a family history
of the disease were less likely to do so.
The
reason, says the study's author, could well be fear.
"Fear
may have a negative impact. People are more afraid of being diagnosed
[if they have a family member with breast cancer]. There is kind of
a denial situation," says Dr. Saleh Rahman, an assistant professor
of public health at Bowling Green State University, whose findings
were presented at the recent Preventive Medicine 2003 meeting
in San Diego.
For
the study, Rahman evaluated the records of 27,778 women, aged 40 to
90, who were entered into the database of the Colorado Mammography
Project. Rahman and his colleagues conducted the analysis from 1994
to 1998, looking at race, educational level, income, insurance status,
and family history to see which factors predicted how women adhere
to the screening recommendations.
Overall,
41.4 percent got a mammogram as recommended, Rahman says. That is
an improvement from earlier years, he adds, noting that a 1987 government
survey found only 30 percent got a mammogram as advised. In Rahman's
study, women who were more highly educated, with higher incomes and
insurance coverage, were most likely to get regular mammograms.
Older
women were more likely to get regular mammograms than the younger
women in general, he also found.
Rahman
had predicted some factors would influence whether women got mammograms,
such as ethnicity, education, age, and income, but he had not thought
that family history would decrease the likelihood.
"We
need to develop behavioral interventions addressing these factors
to neutralize those fears," he says.
The
new study findings are at odds with some other research, says Debbie
Saslow, director of breast and gynecologic cancers for the American
Cancer Society.
"I'm
glad they did the study," Saslow adds, "[but] I was a bit surprised
[by some of the findings."
"We've
seen a lot of national statistics that show black and white women
are getting mammograms at equal rates," Saslow says. "Perhaps this
study has found regional differences or localized differences. Or
it could be things have changed since the analysis was done."
Overall,
research on whether women with a family history of breast cancer get
regular mammograms or skip them has been mixed, Saslow says: "Some
go into denial, some adhere."
In
the Rahman study, the younger women were less likely to get a mammogram.
In years past, Saslow says, there used to be a difference in adherence
between younger and older women, with women over age 65 less likely
to get mammograms. "Now that difference is going away," she says.
The
American Cancer Society recommends that all women
age 40 and older have annual mammograms. This year, an estimated 211,300
new cases of invasive breast cancer are expected to occur among women
in the United States, and 55,700 new cases of localized breast cancer
are expected to be diagnosed. More than 40,000 deaths from breast
cancer are expected in 2003.
Always
consult your physician for more information.
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