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.
BREAST
CANCER & FISH OIL
It
is well known
that the omega fatty acids present in cold water fish can reduce the
risk of
heart disease. Now,
new research,
performed at the University
of Texas
in San
Antonio suggests that fish oil may
be able to inhibit
the growth of breast cancer tumors as well.
This research study, just published in the journal Breast Cancer Research & Treatment,
used a mouse model of
breast cancer to assess the effects of dietary fish oil supplements on
breast
cancer tumors implanted into laboratory mice, and on human breast
cancer cells
grown in laboratory cultures.
Using
sophisticated genetic tests, the researchers found that dietary fish
oil
inhibited genes associated with tumor growth while, simultaneously,
increasing
the activity of genes associated with tumor cell death.
Regression of the implanted human breast
tumors was also observed when mice were fed a diet containing omega
fatty acids
derived from fish oil.
In
order to
further evaluate the effects of fish oil on breast cancer cells, the
researchers
added DHA and EPA, the two active omega fatty acids found in most fish
oil
supplements, to human breast cancer cells growing in culture dishes. Once again, the scientists
found that fish
oil significantly inhibited genes associated with tumor growth, and
simulated other
genes associated with tumor cell death.
In particular, fish oil appeared to increase the activity
of a gene
called PTEN, which belongs to a class of genes called tumor suppressor
genes.
The
PTEN gene
plays a very important role in signaling normal cells to stop dividing
when it
is inappropriate for them to do so.
PTEN, along with multiple other tumor suppressor genes,
also helps to
shunt damaged or abnormal cells into a cellular suicide pathway known
as
apoptosis. Together,
these two
protection mechanisms help to prevent uncontrolled cell growth that
would,
otherwise, result in the formation of tumors.
In many cancers, the PTEN gene becomes inactivated by
mutations,
resulting in uncontrolled tumor growth, as well as tumor cell
resistance to the
apoptosis cell suicide pathway.
Interestingly, an inherited mutation that inactivates the
PTEN gene is
known to cause Cowden’s Syndrome.
People
with Cowden’s Syndrome develop multiple benign tumors, or hamartomas,
of the GI
tract, bones, brain, eyes and urinary tract.
At the same time, this hereditary cancer syndrome is
associated with an
increased risk of cancers of the breast, thyroid and uterus.
This
study’s
finding that fish oil increases the activity of the PTEN gene is a
potentially
important discovery, as are the other apparent anti-tumor effects of
fish oil
on other important cancer-associated genes.
However, my enthusiasm for the findings of this study is
tempered by the
fact that, so far, these anti-tumor effects of fish oil have only been
observed
in cell cultures and in immune-compromised mice that have been
implanted with
human breast cancer cells. As
has been,
unfortunately, shown in thousands of prior research studies using
cultured
cancer cells or laboratory animals, there is no guarantee that these
same
findings will be reproducible in humans.
These exciting findings with a relatively non-toxic
dietary supplement
should, therefore, now be studied in human patients with breast cancer
as a
potential complementary therapy, and as a potential cancer prevention
agent in
women who are at significantly increased risk of developing breast
cancer.
LYMPHEDEMA
AFTER BREAST
CANCER TREATMENT
Arm
lymphedema,
or chronic swelling of the arm, occurs in 10 to 30 percent of women
following
treatment for breast cancer. When
the
lymphatic drainage network in the arm has been disrupted by the
surgical
removal of armpit lymph nodes by the surgeon, or by radiation therapy
to the
armpit area (or, sometimes, following both types of treatment), the
delicate
network of lymphatic vessels that return excess tissue fluid back to
the heart
can become obstructed. This
lymphatic obstruction
can result in chronic swelling of the hand and arm.
Patients with significant lymphedema of the
arm, following breast cancer treatment, may experience considerable
swelling
(edema), heaviness, stiffness and discomfort of the affected hand and
arm.
A
newly published
study in the journal Breast Cancer
Treatment & Research has taken a new look at factors
associated with arm
lymphedema following breast cancer treatment.
This study was performed by researchers at the University
of Southern California,
the City of Hope in California, the
National Cancer Institute in Bethesda,
the Fred Hutchinson
Cancer Center
in Seattle, and the University
of Louisville
in Kentucky.
In
this study,
nearly 500 women who had been diagnosed with preinvasive or invasive
breast
cancer completed an initial interview with study researchers. A follow-up interview was
then performed, on
average, about 4 years later. The
researchers then analyzed the resulting data from these two sets of
interviews.
This
study
confirmed the findings of numerous prior studies that have linked the
surgical
removal of armpit lymph nodes, obesity, and high blood pressure with
chronic arm
lymphedema. In this
study, women with
high blood pressure were found to have almost two-and-a-half times the
risk of
developing lymphedema following breast cancer treatment when compared
to women
who did not have hypertension. Moreover,
this hypertension-associated risk of lymphedema was essentially
equivalent to
the level of risk associated with the surgical removal of armpit lymph
nodes
and with obesity, which is a much higher level of risk than has been
reported
by most prior studies.
Taken together,
the results of this study confirm several previously established risk
factors
for arm lymphedema following breast cancer therapy, but also suggest
that high
blood pressure may, by itself, be a more significant risk factor for
lymphedema
than has been previously appreciated.
The
good news is
that there are strategies available to most women that can address
these lymphedema
risk factors. Recently,
a relatively new
surgical technique has been developed, and allows surgeons to remove
only one
or a couple of lymph nodes (sentinel lymph node biopsy) in the 60 to 70
percent
of breast cancer patients whose breast cancer has not yet spread to
lymph nodes
in the armpit area. Sentinel
lymph node
biopsy has been shown to reduce the risk of lymphedema to one-tenth the
risk
associated with the more radical complete axillary lymph node
dissection that
was formerly performed on all breast cancer patients.
Likewise, losing excess weight may also
reduce the incidence of obesity-associated lymphedema.
The findings of this study also suggest that
achieving good control of hypertension may reduce the volume of edema
fluid
generated in the arms of patients who have undergone breast cancer
therapy, and
may further reduce the risk of chronic lymphedema.
For
additional
information on the subject of chronic lymphedema following breast
cancer
therapy and sentinel lymph node biopsy for breast cancer, please see
the
following links:
http://www.cancersupportivecare.com/Abstracts/asbdpbtps.html
http://meeting.ascopubs.org/cgi/content/abstract/23/16_suppl/8185
http://www.annalssurgicaloncology.org/cgi/content/abstract/15/7/1996
http://www.cancerlynx.com/sln.html
VASECTOMY
& PROSTATE CANCER RISK
Despite
the fact
that the majority of scientific evidence suggests no association
between
vasectomy and the risk of prostate cancer, several previously published
studies
have raised concerns that men with a family history of prostate cancer,
and men
who undergo vasectomy at a young age, may be at an increased lifetime
risk of
developing prostate cancer following vasectomy.
A newly published study in the Journal
of Urology adds further weight to prior studies showing that
vasectomy is not associated with an
increased risk of
developing prostate cancer. This
clinical study was performed by scientists at the Fred
Hutchinson Cancer
Center and
the University
of Washington.
More
than 1,000
men recently diagnosed with prostate cancer were compared to 942 men
without
prostate cancer. All
of these study
volunteers were matched with each other in terms of age, race, and
other
important factors known to be related to prostate cancer risk.
Following
detailed interviews with all of the men participating in this study,
the
researchers found absolutely no difference in the number of men in
either group
who had previously undergone vasectomy.
In both groups of men, 36 percent had previously undergone
vasectomy for
the purpose of sterilization. Furthermore,
the men who had undergone vasectomy at a young age did not appear to
experience
any increased subsequent risk of developing prostate cancer when
compared to the
men who had undergone vasectomy later in life, and when compared to the
men who
had never undergone vasectomy.
The
findings of
this clinical study should be reassuring to men who are considering
sterilization by vasectomy (at least with respect to their lifetime
risk of
developing prostate cancer).
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.
