The
information in this column is intended for informational
purposes only, and does not constitute medical advice or
recommendations by the author. Please consult with your
physician before making any lifestyle or medication changes, or if you
have any other concerns regarding your health.
SLEEP,
MELATONIN &
BREAST CANCER RISK
It has been previously hypothesized
that women who sleep longer at night may have a decreased risk of
developing
breast cancer when compared to those who spend less time sleeping. Although previous clinical
research has not yet
validated this hypothesis, some researchers have still speculated that
the
increased production of the hormone melatonin in the brain during sleep
may
confer some measure of protection against breast cancer. Melatonin, which is
secreted in an area of
the brain that helps to regulate our 24-hour circadian rhythm
(wake-sleep
cycle), is also thought to have some anti-cancer properties. Several studies have
appeared to show an
increased risk of breast cancer, and other cancers, among people who
work night
shifts or rotating shifts, leading some researchers to propose that
decreased
levels of melatonin might be at least partially responsible for this
increase
in cancer risk (melatonin levels decrease when humans are exposed to
light at
night).
A
new clinical research trial
from Singapore,
just published in the journal Carcinogenesis,
evaluated the relationship between duration of sleep and the incidence
of
breast cancer in Singaporean women of Chinese descent.
Institutions involved in this study included
the National University of Singapore, the University
of Southern California,
and the University
of Minnesota.
In
this study, more than
33,000 Singaporean women enrolled in the Singapore Chinese Health Study
were
studied for an average of 11 years.
During this period, 525 of the women were diagnosed with
breast cancer. All
women entering into this study had completed
surveys regarding their sleep habits, and the women also had their
urine tested
for melatonin metabolites.
In
this study, women who
slept an average of 9 or more hours per night were found to be 33% less
likely
to be diagnosed with breast cancer when compared to women who slept 6
or fewer
hours per night. When
melatonin levels
were assessed, the women who slept 9 or more hours per night were found
to have
42% higher levels of melatonin in their bodies when compared to the
women who
slept 6 or fewer hours per night.
The
authors of this study, therefore, hypothesized that the women who slept
longer
hours each night might have experienced a lower incidence of breast
cancer due
to higher melatonin levels in their bodies.
This
is an intriguing study,
although it certainly does not prove that increased durations of sleep
directly
or indirectly reduce breast cancer risk via increased levels of
melatonin (or,
stated another way, that a chronically decreased duration of sleep
increases
breast cancer risk through a reduction in melatonin production). Simply because two or more
separate factors
are observed to occur together does not prove that they are causally
linked to
each other. That
being said, this study
should stimulate the development of a prospective clinical research
trial
looking at the effects of melatonin supplementation on women who are
either at
high risk of developing breast cancer, or women who have already been
diagnosed
with breast cancer. As
there are several
other previous studies that have linked chronically inadequate levels
of sleep
to higher overall mortality, it seems prudent to recommend that one
gets an
average of at least 7 to 8 hours of sleep per night.
MEDITERRANEAN
DIET &
CANCER RISK
Many beneficial health
effects have been attributed to the so-called Mediterranean diet,
including a
decreased incidence of cardiovascular disease and cancer (please see my
recent
Archives for a review of a related clinical study).
Generally speaking, a Mediterranean diet is
based upon moderate-to-high levels of consumption of the following
foods: olive oil,
fresh fruits and vegetables, unrefined
grains, cheese, yogurt, fish and red wine.
At the same time, saturated fats, red meat, and processed
meat products
are consumed very infrequently.
A new clinical research
trial, just published in the British Journal
of Cancer, looked at effects of following the
Mediterranean diet on cancer risk among more than 25,000 Greek men and
women
participating in the “European Prospective Investigation into Cancer
and
nutrition” (EPIC) trial. Participating
research institutions included the University
of Athens,
the International Agency
for Research on Cancer in Lyon,
France,
and Harvard
University.
All participants in this
clinical study completed extensive questionnaires,
including dietary surveys, upon entry into the research trial. The extent of adherence to
a Mediterranean
diet was assessed by a 10-point scale, where a score of “0” indicated
minimal
adherence, and a score of “9” indicated maximal adherence. During an average
follow-up period of almost
8 years, 851 cases of cancer were diagnosed among these more than
25,000 Greek
adults.
When all of the data from
this large public health study was evaluated, it
was found that each 2-point increase in adherence to a Mediterranean
diet was
associated with a 12% reduction in the risk of cancer (the anti-cancer
effects
of a Mediterranean diet also appeared more pronounced in women than in
men, in
this study). Based
upon previous
research findings, the scientists in this study determined that the
extent of
cancer reduction associated with adherence to a Mediterranean diet was
greater
than would have been expected for each individual food item consumed in
a
typical Mediterranean diet, suggesting that added cancer-reducing
benefits
might arise from certain combinations of foods when eaten together.
As with all survey-based
public health studies, biases on the part of those
taking the surveys and those administering them (as well as the people
who
actually designed the surveys) are potential sources of inaccurate data. However, this fine
epidemiological study adds
to a growing list of clinical research data suggesting that following a
Mediterranean diet may significantly reduce your risk of cardiovascular
disease
and cancer. I see
little downside to
adopting a Mediterranean-style diet, assuming, of course, that you
drink red
wine only in moderation.
NEW
TREATMENT FOR
VARICOSE VEINS
Varicose veins in the legs
and feet are a common and annoying health
problem, especially among people who spend a great deal of time
standing. A variety
of treatments are available to
treat varicose veins, although most advanced cases will usually require
surgery
of some sort. Even
with aggressive
surgery, however, varicose veins can return in as many as 40% of cases.
In those patients who
undergo surgical removal of their painful, itching
and unsightly varicose veins, most will undergo a procedure referred to
as
saphenofemoral junction ligation and division.
This procedure involves individually dividing the 5 or
more dilated superficial
leg veins that empty blood into the deeper and larger femoral vein. In the majority of cases
where varicose veins
recur after surgery, the divided superficial veins appear to have
somehow
re-established a connection with the femoral vein.
A new clinical research trial, published in
the journal Circulation, evaluates
a
new surgical procedure that involves the insertion of a physical
barrier
between the femoral vein and the divided superficial venous tributaries
in an
attempt to reduce the risk of recurrence.
This study was carried out at the University
of Otago
in New
Zealand.
In this study, 292 patients
were prospectively randomized to undergo
standard varicose vein surgery either with or without the placement of
a Teflon
patch between the divided veins. All
patients underwent serial postoperative studies of their lower
extremity veins
for a period of 36 months. The
researchers discovered that, at 3 years following surgery, the
incidence of
recurrent varicose veins was twice as common in the patients who had not received the Teflon patch. Among those patients who
did receive the
Teflon patch and who still developed recurrent varicose veins, repeat
surgery
demonstrated that new venous connections developed by detouring around
the
implanted Teflon patch.
This innovative and
prospectively conducted surgical study showed that the
risk of recurrent varicose veins can effectively be cut in half, at 3
years
following surgery, by interposing a Teflon patch between the divided
veins at
the time of the initial varicose vein surgery.
Further research may lead to further refinements in the
Teflon patch
technique used in this study in an effort to further reduce the
incidence of
varicose vein recurrence following surgery.
Disclaimer:
As always, my advice to readers is to seek the advice of your physician
before making any significant changes in
medications, diet, or level of physical activity.
