Advances in imaging technology for early detection of
mesothelioma as well as immunotherapy used in multimodal treatments have
recently shown great promise to extend life expectancy for mesothelioma
patients.
Now, another adjuvant treatment is being developed for
treating pleural mesothelioma called non-ablative hypofractionated hemithoracic
radiation treatment.
A study published in September 2018 by Dr. Marc de
Perrot, the man who pioneered the SMART treatment for pleural mesothelioma, and
Dr. John Cho, the resident Radiation Oncologist at The Princess Margaret Cancer
Center in Toronto, Canada, outlined the results of a series of tests conducted
to determine the viability of this new radiation treatment.
They found several advantages to using hypofractionated
radiation to slow or halt future metastasis of this aggressive cancer.
What are the Benefits of Hypofractionation?
Hypofractionation means that the dose of each blast of
radiation administered to the tumor site is higher and more focused, allowing
for fewer sessions in a shorter period of time immediately before or following
a surgical procedure to resect the tumor.
Normofrationation on the other hand, which is currently
utilized more often in the treatment of various types of cancer, is the
administration of low doses of radiation, over a longer period, and with more
frequent sessions.
The difference between these two methods is striking
given the overall health of the study’s test subjects and their improved
prognoses following treatment with the newer hypofractionated method. Patients
who have to endure weeks of radiation treatments through the normofractionated
method often develope pneumonitis, caused by damage to healthy cell DNA from
the longer duration of treatment.
The study highlighted the specific benefits of the
hypofractionated method stating that:
“Hypofractionated radiation has several advantages. It
can be completed over a few days rather than a few weeks; it can be delivered
in the induction or the adjuvant setting in combination with radical surgery;
for a given total dose, it delivers much greater biological effect (compared to
normofractionation); and, perhaps more importantly, it may provide a specific
activation of the immune system directed against the tumor that could provide a
platform for immunotherapy.”
A Potential New Standard of Treatment
Dr. de Perrot went on to say that the hypofractionation
method limits and even halts the growth of most tumors in new areas such as the
point of entry for surgery, which is often at risk of being seeded by cancer
cells during the resection of diseased tissue.
The non-ablative hypofractionated radiation treatment is
so encouraging primarily because of its ability to work well as a part of
multimodal treatment plans that are being used more often to treat
mesothelioma.
Dr. de Perrot also noted in his report that one of the
reasons for this success is due to the immune response to non-ablative
radiation, which doses are too low to remove the disease at a macroscopic
level. When the non-ablative hypofractionated method is used, it triggers
immune responses in the tumor cells and causes an upregulation and production
of T cells that activate what are known as cytotoxic CD8+ T cells, which speed
up cell death.
This opens new doors for patients with more aggressive
or advanced stages of mesothelioma since this treatment can be used alongside
immunotherapy treatments and radical surgery. With the promising results that
this study has produced, it is likely that with more research this procedure
could become a standard in care for mesothelioma patients.
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