Side-effects
The treatment can be physically exhausting for the patient. Current
chemotherapeutic techniques have a range of side effects mainly affecting the
fast-dividing cells of the body. Important common side-effects include
(dependent on the agent):
- ain
- ausea
and
vomiting
-
Diarrhea or
constipation
- nemia
-
Malnutrition
-
Hair loss
-
Memory loss
- Depression of the
immune system, hence (potentially lethal)
infections and
epsis
- Weight loss or gain
-
Hemorrhage
-
Secondary neoplasms
-
Cardiotoxicity
-
Hepatotoxicity
-
Nephrotoxicity
-
Ototoxicity
Immunosuppression and myelosuppression Virtually all chemotherapeutic regimens can cause depression of the
immune system, often by paralysing the
one
marrow and leading to a decrease of
white blood cells,
ed
blood cells and
latelets.
The latter two, when they occur, are improved with
blood transfusion.
Neutropenia (a decrease of the
neutrophil granulocyte count below 0.5 x 109/itre)
can be improved with synthetic
G-CSF (ranulocyte-colony
stimulating factor, e.g.
ilgrastim,
lenograstim, Neupogen, Neulasta).
In very severe
myelosuppression, which occurs in some regimens, almost all the bone marrow
tem cells
(cells which produce
white and
ed
blood cells) are destroyed, meaning allogenic or
utologous
bone marrow cell transplants are necessary. (In autologous BMTs, cells are
removed from the patient before the treatment, multiplied and then re-injected
afterwards; in allogenic BMTs the source is a donor.) However, some
patients still develop diseases because of this interference with bone marrow.
Nausea and vomiting ausea and
omiting
caused by chemotherapy; stomach upset may trigger a strong urge to vomit, or
forcefully eliminate what is in the stomach.
Stimulation of the vomiting center results in the coordination of responses
from the diaphragm, salivary glands, cranial nerves, and gastrointestinal
muscles to produce the interruption of respiration and forced expulsion of
stomach contents known as retching and vomiting. The vomiting center is
stimulated directly by afferent input from the vagal and splanchnic nerves, the
pharynx, the cerebral cortex, cholinergic and histamine stimulation from the
vestibular system, and efferent input from the
chemoreceptor trigger zone (CTZ). The CTZ is in the area postrema, outside
the blood-brain barrier, and is thus susceptible to stimulation by substances
present in the blood or cerebral spinal fluid. The neurotransmitters dopamine
and serotonin stimulate the vomiting center indirectly via stimulation of the
CTZ.
The 5-HT3 inhibitors are the most effective
ntiemetics
and constitute the single greatest advance in the management of nausea and
vomiting in patients with cancer. These drugs are designed to block one or more
of the signals that cause nausea and vomiting. The most sensitive signal during
the first 24 hours after chemotherapy appears to be 5-HT3. Blocking
the 5-HT3 signal is one approach to preventing acute emesis
(vomiting), or emesis that is severe, but relatively short-lived. Approved 5-HT3
inhibitors include:
olasetron
(Anzemet),
Granisetron (Kytril), and
Ondansetron (Zofran). The newest 5-HT3 inhibitor,
palonosetron (Aloxi), also prevents delayed nausea and vomiting, which
occurs during the 2-5 days after treatment.
Another drug to control nausea in cancer patients became available in 2005.
The
substance P inhibitor
prepitant
(marketed as Emend) has been shown to be effective in controlling the nausea of
cancer chemotherapy. The results of two large controlled trials were published
in 2005, describing the efficacy of this medication in over 1,000 patients.
Some studies
and patient groups claim that the use of
cannabinoids derived from
arijuana
during chemotherapy greatly reduces the associated nausea and vomiting, and
enables the patient to eat. Some synthetic derivatives of the active substance
in marijuana (etrahydrocannabinol
or THC) such as
Marinol may be practical for this application. Natural marijuana, known as
medical cannabis is also used and recommended by some oncologists, though
its use is regulated and not everywhere legal1]
though there are sufficient studies to prove its efficacy.
Other side effects In particularly large tumors, such as large
ymphomas,
some patients develop
tumor lysis syndrome from the rapid breakdown of malignant cells. Although
prophylaxis is available and is often initiated in patients with large tumors,
this is a dangerous side-effect which can lead to death if left untreated.
A proportion of patients report fatigue or non-specific neurocognitive
problems, such as an inability to concentrate; this is sometimes called
post-chemotherapy cognitive impairment, colloquially referred to as "chemo
brain" by patients' groups.
Specific chemotherapeutic agents are associated with organ-specific
toxicities, including
cardiovascular disease (e.g.,
doxorubicin),
interstitial lung disease (e.g.,
leomycin)
and occasionally
secondary neoplasm (e.g.
MOPP therapy for Hodgkin's disease).
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