H
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air loss is a frequent side effect
of cancer treatment, and for many patients, it becomes a real worry.
The sight of a cancer patient covering their hair loss is all too familiar.
Chemotherapy agents
actively target and kill rapidly growing cells, such as those in a tumor. But similar to a
tumor, the hair follicle is a highly active structure with a host of cells that
frequently divide to produce the growing hair.
Because many chemotherapy drugs are designed to
effectively kill all rapidly dividing cells, hair is the unfortunate bystander
that takes the fall along with the cancer cells.
While
some find the thought of losing their hair so distressing that they refuse
chemotherapy, most people will see their locks grow back after the treatment
has finished.
Chemotherapy-induced hair loss
The
level of hair loss, or
chemotherapy-induced alopecia (CIA), depends on the type of cancer, the specific drug, and the dose and
pattern of the treatment.
Many
patients experience the first wave of CIA within 1 to 2 weeks of starting their
treatment.
Areas
that experience high friction during sleep, such as the top of the head and the
sides above the ears, are often the first to see hair loss. Yet the precise
pattern depends on the individual's hair.
Those
hairs that are actively growing will be most affected, but because growing hair
follicles can be arranged in patches or evenly distributed all over the scalp,
it is unfortunately impossible to predict the pattern of hair loss for any
given individual.
By 3 months, hair loss is often complete.
Hair
regrowth after chemotherapy usually starts within 1 to 3 months after the
therapy has finished. Up to 60 percent of
patients report a change in hair color or structure during the first wave of
hair regrowth, with many experiencing curlier hair. However, these changes are
mostly temporary, and hair returns to normal eventually.
The impact of hair loss
Hair
has important functions in culture and communication, and so CIA is
consistently ranked top of the list of traumatic events for many patients that
undergo chemotherapy.
Some patients even consider refusing chemotherapy as
a result of the impending threat of CIA.
Treatments
for CIA are, at best, experimental. Cooling the scalp with ice packs or special
caps was first introduced in the 1970s.
The
theory underlying this treatment is that cooling will narrow the blood vessels
leading to the hair follicles. Some studies have reported success rates of up to 50 percent
with this technique, but there is clearly a need for more effective therapies.
On the hunt for new drug targets
Very
little is known about how chemotherapy drugs cause CIA. Most information stems
from studies using mouse models.
Here, research has shown that programmed cell
suicide, or apoptosis,
is the most likely cause of cell death in the hair follicle, causing the hair
to fall out.
Researchers in
the Department of Medicine at the University of Chicago, IL, used genome-wide
association studies to compare the genetic signature of breast cancer patients
who had experienced CIA with that of those who had not.
They
found several candidate genes that might be implicated in the loss of
functional hair follicles. One of these, CACNB4, is part of a calcium channel
that plays an important role in cell growth and apoptosis. Another gene, BCL9,
was active in a subset of CIA patients and is known to play a role in hair
follicle development.
Armed
with this knowledge, scientists are continuing their quest to develop effective
inhibitors of chemotherapy-induced hair loss, hoping to reduce the burden that
this unwanted side effect has on cancer patients.
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