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Abdominal Cancer, Constipation, and Anorexia 143

indication for permanent or long-term opioid therapy. Can we do something about the
In fact, this approach is based on an interesting hepatic weight loss?
mechanism: morphine is metabolized in the liver into
its active products, while the opioid antagonist nalox- Although it would be tempting to give the patient par-
one is completely metabolized in its fi rst pass through enteral nutrition, if available, it is well known that this
the liver into inactive forms. Th erefore, the antagonist method does not infl uence the course of the weight
would only be active at the intestinal opioid receptors, loss and even poses a risk for the patient (e.g., refeed-
specifi cally antagonizing the constipation side eff ects of ing syndrome, infections from catheters). Th e excep-
morphine or other opioids. tion to this rule is the special situation when the pa-
Some opioids are now available that are a com- tient requires surgery, when perioperative parenteral
bination of agonist and antagonist. Unfortunately, they nutrition is indicated to reduce further weight loss.
are available in only a handful of countries, and due to In general, our main target is to educate patients and
patent protection, they are rather expensive. A cheap help them, if possible, with some symptomatic treat-
alternative is to provide the patient with oral naloxone, ment to increase appetite. Th is support may be very
which—if available—is a low-cost substance and has an- helpful for the patient, since eating is one of our main
ticonstipation eff ects in a dose range of 2–4 mg q.i.d. A “social” activities. Although there will be no relevant
recent development is methylnaltrexone, which is a se- weight gain, the increased appetite will have a positive
lective opioid antagonist. It is administered subcutane- eff ect on the patient’s general well-being. Two sub-
ously and has a predictable eff ect within 120 minutes stances have been shown to have a positive eff ect on
for more than 80% of treated patients. Due to its route appetite and may be tried if they are locally available.
of application and high costs, its use is limited to “emer- First, the patient should be encouraged to smoke or
gency situations,” when intestinal paralysis, not merely eat cannabis, if available. An artifi cial cannabis prod-
obstruction, is imminent. uct is available on the pharmaceutical market (delta-
9-tetrahydrocannabinol), but it is unaff ordable for
If my patient complains about most people if it is not covered by insurance, as is the
case in most countries of the world. Th e second op-
fatigue and loss of appetite,
tion would be the use of steroids. A low dose of dexa-
what do I tell him? methasone (2–4 mg once daily), prednisolone (20 mg

once daily), or another steroid at an equipotent dose
Patients must be educated about the fact that the
may improve anorexia.
cancer induces certain changes in the central regu-
lation of appetite. In abdominal cancer, about three-
quarters of patients experience weight loss of more Is there also a good
than 5% monthly in the advanced stage of cancer recommendation for my patient
(breast cancer and prostate cancer are exceptions complaining of fatigue?
to the rule, causing only moderate weight loss). We
know now that cytokines, which play a prominent Fatigue is a term describing major exhaustion and
role in infections, are released from cancer cells should not be confused with depression or sedation.
and are involved in changes in appetite. They influ- Depression usually goes along with diffi culties in fall-
ence the melanocortin system in the central nervous ing asleep, constant “thinking in circles,” lacking drive,
system (the hypothalamus), thereby reducing the especially in the morning hours, and general loss of
patient’s appetite. Even high caloric intake cannot interest, while sedation means falling asleep again and
prevent weight loss. Therefore, patients should be in- again for short periods (maybe the opioid dose is too
structed to continue eating what they like best, but high?). If fatigue is diagnosed, we have to admit to the
they should not be encouraged to force their nutri- patient that it can hardly be infl uenced and is a “pro-
tional intake. The patient’s family should be instruct- tective” function of the body to save energy because
ed likewise, because they might feel that they have to of the cancer. While pharmacological options such as
“feed” the patient more since they see the continuous methylphenidate have been very disappointing, some
reduction in body weight. patients have reported having less fatigue with a high