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Spontaneous regressions
Are
the observed
decreases in tumor burden, which is relatively common in patients with
indolent lymphomas. Depending on the source,
as many as 20% to 30% of patients will experience regressions at
some time in the clinical course of their disease. This observed
clinical tendency is also called waxing and waning.
-
The natural history of
initially untreated low-grade non-Hodgkin's lymphomas.
N Engl J Med. 1984 Dec 6; 311(23): 1471-5. PMID:
6548796
Some Terminology:
Spontaneous regressions
and spontaneous
remission are sometimes used interchangeably,
but these terms can have different meanings to different
people:
Remission
is most often defined as the absence of disease activity
(stable disease), which is common in indolent lymphomas
...
... but remission is sometimes thought of and used to
describe being free of observable disease -- or having no
evidence of disease (NED).
... Given this ambiguity, we propose that spontaneous
regression be used to describe
decreases in tumor burden that appear to occur spontaneously,
without treatment.
The term waxing
and waning is also used to describe
the uneven course of lymphomas, particularly of the indolent (slow
growing) types. Waxing means progressing, and waning means
regressing.
We propose that waxing and waning
be used to describe transient or short-term fluctuations in the
size of lymph nodes that could be accounted for by inflammation
and other factors unrelated to the actual number of malignant
cells. You might think of waxing and waning as being similar to daily
fluctuations in the stock market that are not related to longer trends.
Finally, how does one distinguish between waxing
and waning and spontaneous
regressions?
It may be that with spontaneous regressions there will be other
signals that suggest true improvements in the state of the
disease, such as improving blood counts, decreasing LDH, and
observable improvements in how the patient feels and
performs.
also see Remission, Response and
Survival terms
Regressions are
always welcomed by the patient, but this characteristic of the
disease also makes it more difficult
for investigators
to evaluate new treatments - requiring larger numbers of patient in
clinical trials.
How Might it Happen?
Here are some theories taken
from the literature, with some layperson-speculation mixed in:
Immune recognition of the tumor
cells may produce an immune response against the tumors, which
could include the production of antibodies against antigen targets
on the tumor, or NK cell direct killing.
Viruses may infect lymphoma cells
as they do other lymphocytes, and thus make them more recognizable
to other immune cells. This could be the mechanism behind the
measles vaccine which is being studied in clinical trials for
lymphoma.
Cytokine signals (chemical
messages) may induce lymphoma cells to differentiate (mature to a benign
form), or induce them to die naturally in a process called
apoptosis.
Stress might raise levels of natural steroids and cause
temporary regressions.
Inflammation may account for waxing and waning of lymph nodes, which
would mean that both the waxing and waning are not real indications
of tumor progression or regression. If inflammation is caused by
immune system activity against the tumor, real regression may happen
as well for some people.
Hypoxic (low oxygen levels) that form in tumors may cause them to
implode when necrotic (dead areas) form in the center. NOTE: It's
also possible that low oxygen conditions can cause cells to adapt
and become more aggressive or refractory.
Placebo Effect Stephen
Barrett, M.D. - quackwatch.org
"Recovery from illness, whether it follows self-medication,
treatment by a scientific practitioner, or treatment by an
unscientific practitioner, may lead individuals to conclude that the
treatment received was the cause of the return to good health."
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