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Spontaneous regressions
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 reasons for spontaneous regressions have not
been identified and there may be different reasons in each case. The biology of the lymphoma
varies and the interactions between the tumor
and bystander cells in the tumor microenvironment are very complex
and can vary for each of us - even when we have the same diagnosis.
-
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).
... Spontaneous
regression is often 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.
Waxing and waning might
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. Waxing and waning is similar to the daily
fluctuations in the stock market that may or may not be 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 variable 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.
Antigen in the body may
influence the behavior of lymphoma cells which like normal
lymphocytes may react to the presence or absence of stimulating
antigens (pathogens, virus, allergens and so on)
Variation in the mutations within the tumor
cells may cause some lymphomas to be more normal in their
behavior - less likely to grow and persist; and more likely to
regress.
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 microenvironments (with low oxygen levels) may cause
tumors 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."
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.
Stress might raise levels of natural steroids and cause
temporary regressions.
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