Lack of nutrition
deprives individual cells of the carbohydrates, fatty acids, as well as
amino acids, the building blocks for complex sugars, fats and proteins,
respectively, that cells need to survive. The body senses this deficiency
and begins to degrade healthy tissue for sources of energy. The degradation
of healthy tissue is responsible for loss of lean body and muscle mass.
Often, the body's consumption of energy is also increased. In other words,
the body's metabolic rate, even at rest, is significantly higher. Exactly
how these metabolic changes occur is not completely understood. These
changes are thought to be responsible for the patient's inability to gain
weight even when caloric intake seems to be adequate.
Drastic weight loss is
an independent risk factor for poor survival. Cachectic patients have worse
outcomes with surgery, chemotherapy and radiation therapy. Cachexia is also
an under recognized cause for distress and anxiety among patients and their
family members as changes in body image are readily noticeable by everyone.
A number of
therapeutic agents for cancer cachexia have been investigated in the recent
past. However, most studies are limited to a single tumor type and may or
may not be applicable to all patients suffering from this condition. One of
the biggest challenges in the treatment of cachexia is the concern that
extra calories would only feed the tumor rather than the starving healthy
cells. For this reason any potential therapy must act through mechanisms
that do not support tumor growth and spread.
One commonly used
agent is essentially a hormone called megestrol acetate (Megace). This
compound is a synthetic progestin hormone which works by interfering with
the normal estrogen cycle thereby decreasing hormone levels overall. One of
its side affects is appetite stimulation and weight gain. Its application in
cachexia came from this observed side effect when the drug was first used to
treat hormone responsive breast cancer. Unfortunately, the weight gain is
usually temporary and comes primary as fatty tissue, rather than protein and
muscle mass. All the same, maintaining weight and appetite are still
important as they improve a patients sense of well being and may serve to
increase activity level.
Some patients have
been placed on corticosteroids in an attempt to increase weight. However, as
with progestin, weight gain tends to be temporary and after a number of
weeks, its use becomes counter productive. With prolonged use, steroids
interfere with muscle synthesis. It is unclear why these agents should work
in the first place. One theory is that steroids interfere with cytokine
production and action.
There is much research
and recent press on the benefits of fish oils, especially ones that contains
long-chain omega-3 fatty acids. A number of studies showed that fish oil
supplements can stabilize weight loss and even increase weight in people
suffering from cancer cachexia due to pancreatic cancer. One study in
particular was able to show that omega-3 fatty acids can reduce inflammation
and protein breakdown.
A drug called
Thalidomide was initially marketed as a sleeping assisting medication. It
was pulled off the market in the early 1960 when was it was proven to be
responsible for multiple birth defects when used by pregnant women. Now this
drug may be used with caution to help people with cachexia. The presumed
mechanism of action appears to be cytokine interference.
currently under study include the statin family of anti cholesterol
medications and angiotensin-converting enzyme inhibitors that are used most
often for hypertension. These medications are thought to have an
anti-inflammatory component that maybe beneficial in suppressing cytokine
production. A class of antibiotics known as the macrolides, which include,
agents like Erythromycin and Azythromycin, has also been touted to possess
anti-inflammatory properties. Creatin is a commonly used dietary supplement
by athletes presumed to increase muscle strength and size. Its safety and
efficacy is under study in cancer patients currently. Other supplements
under consideration include amino acid supplements like cysteine which work
toward increasing lean body mass.
The most drastic
treatment for cachexia, and one which is reserved as a last resort, is
parenteral nutrition. Providing nutrients intravenously is both dangerous
and expensive and is used only in desperate situations on a temporary basis.
For short periods of time it can improve a patients' protein and electrolyte
balance and assist a patient through a difficult course of therapy. For
prolonged periods, the risk of life threatening infections outweighs the
As more is learned
about cachexia, it is now clear that it is not due exclusively to a caloric
intake deficiency. Nor is it a consequence of tumor competing with healthy
cells for the available nutrients. It is rather a complex metabolic change
within the body. The metabolic changes are due to the presence of a
malignancy and the inflammatory cytokines that it is thought to produce. The
new knowledge in the mechanisms of cachexia will lead to improved
treatments, which will translate to improved quality of life.
believe the next generation of cachexia research and treatment will focus on
inhibitors of protein degradation and stimulants of protein synthesis.
Ideally, of course, improvements in anti cancer therapy may make
anticachexia treatment obsolete.
Disclaimer: These statements have not been evaluated by the Food and Drug
Administration. The products and information contained herein are not
intended to diagnose, treat, cure or prevent any diseases
or medical problems. This is not intended to replace your
doctor's recommendations. The information is provided for educational
purposes only. Nutritional benefits may vary from one person to another.