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May
2001
Ultrasound
Not an Accurate Screening Test for Down Syndrome
About
5,000 babies are born each year with Down syndrome, a condition that causes
varying degrees of mental disabilities and physical abnormalities. Because
of the difficulties associated with raising a child with Down syndrome,
some women choose to test for the condition.
The most reliable prenatal test for Down syndrome is amniocentesis, a
process in which the clinician inserts a needle through the woman's abdomen
to remove and analyze a sample of amniotic fluid. While the test is about
99% accurate, it increases the risk of miscarriage anywhere from 0.5-1%.
Because of the risks associated with amniocentesis, some clinicians have
suggested that ultrasound should be used as a screening test to determine
whether certain markers exist that suggest the baby may be born with Down's
and that an amniocentesis is warranted. Ultrasound is a painless, non-invasive,
general screening device that uses sound waves to view the fetus. It is
widely used during the second trimester of pregnancy as a routine part
of prenatal care.
While the idea of a non-invasive prenatal test is encouraging, ultrasound
is not an accurate method of screening for Down syndrome, according to
a study in the Journal of the American Medical Association. The
analysis of 56 studies published between 1980 and 1999 found that only
one of the markers found on an ultrasound, a thickening at the back of
the neck, was reliable enough for a physician to recommend amniocentesis.
Other markers present on an ultrasound, such as brain cysts and bright
spots on the bowel, were often harmless and not reliable indictors of
Down syndrome. The researchers concluded that the dangers associated with
an amniocentesis based on most ultrasound markers are greater than the
possibility of having a child born with Down's.
May
2001 Update
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National
Cholesterol Education Program Releases New Guidelines for Treating and
Preventing High Cholesterol
On May 15, 2001, the National Cholesterol Education Program (NCEP) —
coordinated by the National Heart, Lung, and Blood Institute (NHLBI) —
released the first major revision of its recommendations for detecting
and lowering high cholesterol in adults since 1993.
One of the fundamental features of the new guidelines is the accurate
assessment of heart disease risk using a new "global risk assessment
tool" that combines multiple risk factors into a measure of a person's
absolute risk of developing coronary heart disease within the next 10
years. According to the guidelines, patients who have a risk of 20% or
higher should receive aggressive therapy to control cholesterol levels.
In addition to aggressive treatment of high LDL cholesterol, as laid out
in the 1993 report, the revised guidelines also recommend a more assertive
treatment approach for diabetes, low HDL levels, and high triglyceride
levels.
Specific changes include:
- Treating
high cholesterol more aggressively for those with diabetes, even if
they do not have heart disease.
- A
full lipid profile (which measures total cholesterol, LDL, HDL,
and triglycerides) as the first test for high cholesterol (rather than
simply testing total cholesterol and HDL and performing a full lipid
profile only if total cholesterol is high).
- A
new level at which low HDL becomes a major risk factor for heart disease.
The 1993 guidelines defined a low HDL as less than 35 mg/dL; now it
is less than 40 mg/dL.
- More
aggressive treatment of high triglyceride levels.
- Advising
against the hormone replacement therapy (HRT) as an alternative to cholesterol-lowering
drugs for post-menopausal women.
Another
key change in the guidelines is intensified lifestyle recommendations
regarding nutrition, exercise, and weight control to treat high cholesterol.
The updated diet advises that less than 7% of daily calories come from
saturated fat and limits dietary cholesterol to less than 200 mg per day.
It also allows up to 35% of daily calories from total fat, provided most
come from unsaturated or monounsaturated fat, which doesn't raise cholesterol
levels. Additionally, the guidelines strongly underscore the need for
weight control and physical activity, both of which improve various heart
disease risk factors.
The revised recommendations also emphasize careful attention to the metabolic
syndrome, a particular cluster of cardiovascular risk factors that
is becoming increasingly common in the United States. Characteristics
of metabolic syndrome include too much abdominal fat, high blood pressure,
high blood sugar, elevated triglycerides, and low HDL.
For more information, see the "Live Healthier, Live Longer"
Web site by going to the NHLBI home page at www.nhlbi.nih.gov
and clicking on ATP III Cholesterol Guidelines under Highlights.
|
2001
Cholesterol Guidelines
|
| Total
Cholesterol Level |
Total
Cholesterol Category |
| Less
than 200 mg/dL |
Desirable |
| 200-239
mg/dL |
Borderline
High |
| 240
mg/dL and above |
High |
| LDL
Cholesterol Level |
LDL-Cholesterol
Category |
Less
than 100 mg/dL
|
Optimal |
| 100-129
mg/dL |
Near
optimal/above optimal |
| 130-159
mg/dL |
Borderline
high |
| 160-189
mg/dL |
High |
| 190
mg/dL and above |
Very high |
Trigylceride
Level
|
Triglyceride
Category |
| Less
than 150 mg/dL |
Normal |
| 150-199
mg/dL |
Borderline high |
| 200-499
|
High |
| Greater
than or equal to 500 |
Very
high |
| HDL
Cholesterol Level |
HDL-Cholesterol
Category |
| Less
than 40 mg/dL |
Low
(representing increased risk) |
| 60
mg/dL and above |
High
(heart protective) |
|
|
Three
Categories of Risk that Modify
LDL Cholesterol Goals
|
|
Risk
Category
|
LDL
Goal (mg/dL)
|
| Coronary
Heart Disease (CHD) and CHD equivalents |
Less
than 100 |
| Multiple
(2+) risk factors |
Less
than 130 |
| 0-1
risk factor |
Less
than 160 |
|
| Risk
factors (exclusive of LDL cholesterol): cigarette smoking; blood pressure
greater than or equal to 140/90 mm Hg or on antihypertensive medication;
HDL cholesterol less than 40 mg/dL; a family history of coronary heart
disease before age 55 in a father or brother or age 65 in a mother
or sister; age above 45 for men and 55 for women |
May
2001 Update
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TNF
Inhibitors Effective for Treatment of Rheumatoid Arthritis
Two
members of a new class of drugs have been found to reduce the joint damage
associated with rheumatoid arthritis. Rheumatoid arthritis (RA) is an inflammatory
disease that causes pain, swelling, stiffness, and progressive loss of function
in the joints.
Two studies published in the New England Journal of Medicine evaluated
the effectiveness of TNF inhibitors, drugs that neutralize the inflammatory
protein known as tumor necrosis factor (TNF). TNF is overproduced
in the joints of patients with rheumatoid arthritis and is believed to be
responsible for much of the joint damage in RA.
In one study, conducted at the Johns Hopkins University, in Baltimore, etanercept
(Enbrel) was compared to methotrexate in 632 patients with early stage rheumatoid
arthritis. Etanercept acted more rapidly to decrease symptoms than methotrexate.
In addition, etanercept was more effective at slowing the progress of joint
erosion; the rate of joint damage, as measured by X-rays, was significantly
reduced in the etanercept group compared to the methotrexate group. After
one year of treatment, 72 percent of the etanercept patients had no progression
in joint erosion compared to 60 percent of the methotrexate-treated patients.
The second study, conducted at the University of Texas Southwestern Medical
Center in Dallas, followed 428 patients with chronic, active rheumatoid
arthritis, for 12 months. The researchers found that a combination of the
TNF inhibitor infliximab (Remicade) and methotrexate significantly reduced
the symptoms of RA and halted progression of joint damage compared to treatment
with methotrexate alone. Nearly 52 percent of the patients taking the infliximab
and methotrexate combination showed symptom reductions, compared with 17
percent of methotrexate-only patients. X-ray examination showed that joint
damage came to a halt in patients given the drug combination. In addition,
joint damage decreased in 40-55 percent of patients on the combination
therapy, implying that some damage had been repaired. Meanwhile, joint damage
progressed in the group given only methotrexate. The combination therapy,
which was well tolerated, also significantly improved quality of life.
Methotrexate, the standard rheumatoid arthritis medication, was approved
more than a decade ago for treating certain types of arthritis and skin
conditions. However, it can cause serious side effects including liver damage.
In contrast, both TNF inhibitors were well tolerated.
An estimated one percent of the adult U.S. population has rheumatoid arthritis,
and is about two to three times more common in women than men.
May
2001 Update
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Study
Shows Fish Consumption Protects Against Stroke, But FDA Suggests Pregnant
Women Should Take Caution
A
large study in the Journal of the American Medical Association
(JAMA) recently showed that regularly eating fish might protect against
ischemic stroke, which is the most common type of stroke. Numerous studies
have already shown an association between fish consumption and a reduced
risk of heart disease. But there is a caveat. The Food and Drug Administration
(FDA) recently warned that pregnant women and women who are of childbearing
age who may become pregnant, should avoid certain types of fish that contain
high levels of mercury, which may be harmful to their unborn children.
Results of the Nurses' Health Study, published in the JAMA article,
involved nearly 80,000 women. It showed that women who ate fish two to
four times a week had a 48% lower risk of ischemic stroke —
the kind caused by blood clots —
than women who ate fish less than once per month. Even women who ate fish
only once a week or less had a risk reduction, but it was not statistically
significant. These results held true primarily among women who did not
regularly take aspirin, which prevents the formation of blood clots. Omega-3
fatty acids, the protective substances found in fish, reduce levels of
fats related to cardiovascular disease and help prevent blood clotting.
Dark, oily fish such as mackerel, salmon, and sardines are a good source
of omega-3 fatty acids.
Although pregnant women need not give up fish —
and its beneficial health effects —
altogether, they should be careful about what types of fish they eat.
The FDA has advised that pregnant women and those who may become pregnant
stop eating shark, swordfish, king mackerel, and tilefish. These large,
long-living fish contain hazardous levels of methyl mercury, a
form of mercury that can accumulate in a woman's body and affect the developing
central nervous system of an unborn child. This can lead to babies with
slower cognitive development. As an extra precaution, the FDA advised
that nursing mothers and young children also avoid these fish. Mercury
gets into both fresh and salt water through industrial pollution.
Some critics feel the FDA's mercury warnings are not strong enough. A
report by the National Academy of Sciences suggested the exposure limits
for mercury should be four times stricter.
While this controversy remains unresolved, the FDA encouraged pregnant
women to continue to eat a variety of other fish, containing very low
levels of mercury, as part of a balanced diet. Among other health benefits,
the fatty acids in fish enhance brain development. According to the FDA,
women can safely eat up to 12 ounces of fish per week. Fish that contain
low levels of mercury include shellfish, canned fish, smaller ocean fish,
and farm-raised fish. Women who eat fish caught by family or friends should
contact their local health department for advice on the safety of fish
from local waters.
May 2001 Update
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FDA
Approves Gleevec to Treat Leukemia
Chronic
myelogenous leukemia (CML), one of four main types of leukemia, strikes
about 5,000 people every year. On average, patients live 3-4 years after
receiving a diagnosis of CML. Last week, the FDA approved Gleevec (imatinib
mesylate, also known as STI-571) as an oral treatment for CML.
Gleevec has been shown to substantially reduce the level of cancerous
cells in the bone marrow and blood of treated patients. In clinical trials,
90 percent of patients in the first phase of CML went into remission within
the first six months of taking Gleevec. Of patients in the second phase
of CML, 63 percent went into remission with Gleevec. The drug produced
few side effects.
Additional studies need to be done to determine how long the effects of
this drug lasts, whether patients become resistant to the drug, and, most
importantly, whether Gleevec can actually extend a patient's life.
Still, the results are promising. Currently, the only cure for CML is
a bone marrow transplant. Even if a patient is lucky enough to find a
marrow donor match, the procedure is successful less than 2/3 of the time.
Interferon, a widely used treatment for CML, can extend a patient's life
for up to two years, but it has several serious side effects and does
not cure the disease. Gleevec may be used in patients in the early stage
of CML who do not respond to interferon therapy, and in patients in the
later stages of CML.
Most people with CML have a chromosomal abnormality, known as the Philadelphia
chromosome, in which portions of two different chromosomes are switched.
The result is the creation of an abnormal protein that allows the uncontrolled
production of white blood cells, which can interfere with the function
of other organs in the body. Gleevec blocks a signal sent out by the abnormal
protein, thus blocking the rapid growth of white blood cells.
The FDA's approval of the drug came after a surprisingly short 2 ½
months. Most drugs that, like Gleevec, are granted a priority review,
take six months to approve. The approval was based on three separate studies
that involved about 1,000 patients with CML. The drug has generated enthusiasm
in the medical community because it targets a specific, cancer-causing
protein, without damaging other cells.
Scientists at an American Society of Clinical Oncology meeting announced
earlier this week that Gleevec had also produced remission in 180 patients
with advanced cases of an intestinal cancer known as gastrointestinal
stromal tumor (GIST). Until now, GIST cancers have been incurable; GIST
patients normally die within one year of receiving their diagnosis.
May 2001 Update
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Hormonal
Therapy Recommended for All Hormone-Receptor-Positive Breast Cancers
In a statement issued late last year, the National Institutes of Health
recommended that all women who have hormone-receptor-positive breast cancer
receive hormonal therapy in addition to their primary treatment (surgery
alone or surgery plus chemotherapy). This recommendation holds regardless
of a woman's age, menopausal status, tumor size, or whether the cancer
has spread to the lymph nodes.
Hormone-receptor-positive cancers grow in response to the hormone estrogen,
which is produced by the ovaries. Tamoxifen (Nolvadex, Tamoplex), the
most widely used hormonal therapy, works by blocking estrogen receptors
on breast cancer cells. It is used to halt, slow, or prevent tumor growth.
Studies have shown that women who take tamoxifen for five years reduce
their annual risk of a recurrence of breast cancer by 40%. Taking the
drug for more than five years offers no additional advantage, and it increases
the risk of toxic effects.
Premenopausal breast cancer patients under the age of 50 reap a significant
benefit from adjuvant tamoxifen therapy. Results from a small study show
that women under 50 who received tamoxifen in addition to chemotherapy
had a 40% reduction in recurrence and a 39% reduction in death compared
with women who had chemotherapy alone. These results are not conclusive,
however, because of the small trial size. A study currently underway in
Canada may provide more reliable results.
Postmenopausal women with very small, low-grade tumors, however, may experience
only a small overall benefit from tamoxifen. After menopause, women have
lower levels of estrogen in their bodies. Studies have shown that women
in this group who undergo chemotherapy but do not take tamoxifen may live
as long as women of the same age with no history of breast cancer. Because
tamoxifen can cause rare, serious side effects such as blood clotting
and endometrial cancer, postmenopausal women and their physicians should
weigh the benefits of taking the drug against the risks.
May
2001 Update
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