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Cancer Answers: Radiation Therapy for Cancer Treatment, April 18, 2010

July 20, 2019
Dr. Kenneth Roberts, Radiation Therapy for Cancer
Treatment
 April 18, 2010Welcome to Yale Cancer Center Answers with Dr. Ed Chu and
Dr. Francine Foss, I am Bruce Barber.  Dr. Chu is Deputy
Director and Chief of Medical Oncology at Yale Cancer Center and
Dr. Foss is a Professor of Medical Oncology and Dermatology
specializing in the treatment of lymphomas.  If you would like
to join the conversation, you can contact the doctors
directly.  The address is canceranswers@yale.edu
andthe phone number is 1888-234-4YCC.  This evening
Ed and Francine welcome Dr. Kenneth Roberts.  Dr. Roberts is a
Professor of Therapeutic Radiology and Medical Director of the
Yale-New Haven Shoreline Medical Center, Department of Radiation
Oncology.  Here is Ed Chu.Chu
 Why don't we start off by defining for our listeners out there
what radiation oncology is?Roberts
Radiation therapy is actually a very old treatment.  It dates
back more than 100 years, but has had profound changes during my
career over the last several decades.  It is part of the
armamentarium of treating cancers, which includes surgery,
chemotherapy, and a host of other treatments, but is integrated
with the main therapies of cancer management, again surgery,
chemotherapy, and radiotherapy, and specialists who have expertise
with those different modalities have to work together. 
Broadly speaking, about 50%-60% of all cancer patients will require
radiotherapy at some point in their treatment course.Chu
 Ken, maybe to simplify things for our listeners, when you give
radiation therapy, what are you actually giving, what are they
being treated with?Roberts
For the most part we are delivering high energy x-rays into a tumor
and that causes a series of very short chemical reactions.  We
deposit radiation doses in the body that interact with DNA, the
genetic code, to cause the desired results of killing cancer
cells.Foss
Are there different types of radiation therapy?Roberts
Sure, radiation can be delivered externally from the body or
radiation can be delivered by implanting radiation sources directly
into a tumor.  Most of what I do as a radiation oncologist is
external radiation techniques, and these days the most common type
of machine for delivering radiotherapy is called the linear
accelerator, and that machine can produce high energy x-rays that
we can direct into a patient's body and their disease site,
orienting treatment beams coming in from different angles and
having multiple beams overlapping, so that you concentrate the
radiation dose to where a tumor is located.Foss
Ken, folks are familiar with radiation exposure say from
radioactive spills and power plants, is this the same type of
radiation, or is it different?Roberts
This would be different.  When there are those types of
radiation accidents there are4:07 into mp3 file 
http://www.yalecancercenter.org/podcast/apr1810-cancer-answers-roberts.mp3
 radioactive materials that are released into the environment and
those materials can give off a variety of different types of
radiation.  In this case, linear accelerators are not
depositing a radioactive substance into patients or into the
environment, the machine just generates high energy x-rays, so it's
different in that sense.Chu
 Ken, over the years on the show we have talked about the use of
gamma knife, or Cyberknife, can you explain to us what the
difference is between gamma knife, Cyberknife, and the use of x-ray
therapy via this linear accelerator?Roberts
You are bringing up some of the more recent and sophisticated
radiation treatment devices.  With a linear accelerator one is
delivering typically a single, larger beam, to encompass a region
of the body. With these newer technologies, as you mentioned gamma
knife and Cyberknife, there are similarities to linear
accelerators, particularly with Cyberknife, but what we are doing
is delivering very small radiation treatment beams, pencil thin
beams if you will, which can then be oriented to come in from
different directions and angles into a tumor target and one is able
to then focus the radiation dose very tightly and specifically to a
tumor and deliver a very little radiation dose to nearby normal
tissues.Chu
 So presumably then, for those types of radiation therapy
treatments, the issue of toxicity might be less than more
traditional forms of radiation therapy?Roberts
Right, that's correct, but it depends on the circumstance when you
need to use these different types of radiation treatments.  If
you are trying to target a very small tumor, say a single brain
metastasis, it is appropriate to use a gamma knife or even a
Cyberknife to deliver very focused radiation just to a very small
tumor that's in the brain.  On the other hand, if the goal of
the therapy is to treat a broader area of the body, where there
could be a microscopic burden of tumor cells, these very focused
treatments are not appropriate and more traditional forms of
radiotherapy are more effective and useful.Foss
Are these more focused and new techniques available in all centers,
or is this something that a patient would have to travel to a
specific center for?Roberts
They are very expensive technologies and they have limited
availability at particular centers.  At Yale, we have gamma
knife technology for treating intracranial tumors and this is also
sometimes called radiosurgery, these very focused types of
radiation techniques. There has been the development of
radiosurgery for treatment elsewhere in the body, called body
radiosurgery, and at Yale we use a linear accelerator that has been
specifically adapted
 for that purpose in order to treat, with these very small pencil
thin beams, other problems, say a small lung cancer for
instance.8:28 into mp3 file 
http://www.yalecancercenter.org/podcast/apr1810-cancer-answers-roberts.mp3Chu
 In the news there is a lot of attention being placed on perhaps
the latest form of radiation therapy, proton beam radiation
therapy, can you say a word or two about that approach?Roberts
Sure, that's a very exciting development in the field of radiation
oncology.  It's also an extraordinarily expensive technology
where currently it would take 200 to 300 Million dollars to set up
a treatment facility.  So, there are limited numbers of these
photon facilities throughout the world because of the huge
financial barriers, but the advantage of protons is that they lack
an exit portion of the radiation beam.  They also have
characteristics that deposit radiation at a very concentrated
amount inside the patient at a pre-determined depth depending on
where the tumor is located.  These physical characteristics of
this type of radiation are extremely important and useful since one
has the ability to reduce the exposure of normal tissues in a
particular problem and reduce the complications from exposure of
critical normal tissue right next to the tumor.  For instance,
proton therapy was used for a rare tumor called chordoma, which
occurs in the base of skull right next to the brain stem, and it
has been found that with the proton beam radiotherapy you are able
to increase the dose of radiation one can deliver to control the
disease and yet not cause profound neurologic problems because you
are able to control and eliminate doses going to the brain
stem.Foss
Ken, with all of these different types of radiation therapy, how do
you decide what type to treat an individual patient with, is there
a process that you go through?Roberts
Well, that's the broad question.  Obviously, it is highly
individualized and dependent on the particular problem and, first
of, in working in a collaborative manner with other specialists for
a given cancer with a diagnosis one needs to determine the exact
extent of the disease, determine the stage, and come up with a
joint treatment integrating chemotherapy, surgery, and
radiotherapy.  So, it really depends on a whole host of
factors and circumstances as to how we employ radiotherapy. 
It is probably best to take a concrete example, say breast
cancer.  Once a breast tumor is diagnosed say by mammography
or a woman feeling a lump, it's biopsied and if a cancer diagnosis
is established then one needs to determine if this is localized or
if it has spread anywhere.  If it's a localized problem, a
common treatment scheme is to think about surgery to remove the
lump and potentially even biopsy lymph nodes to see if there is any
spread.  With that information one can then determine the
extent of disease and then decide whether systemic therapy or
chemotherapy or hormone therapy is going to be necessary, and then
radiotherapy has a role in that sort of situation to help with
controlling the disease within the breast and potentially within
the lymph nodes in the vicinity of the breast.  Over the last
several decades, radiotherapy for this particular problem has been
shown to allow for less extensive surgery to be performed, so
rather than a mastectomy, often times women just need to undergo an
excisional biopsy, or so called13:37 into mp3 file 
http://www.yalecancercenter.org/podcast/apr1810-cancer-answers-roberts.mp3lumpectomy, and then radiotherapy allows for treatment that
avoids more disfiguring surgery.  And of course there are
sometimes reasons why mastectomy is important and sometimes after
mastectomy radiotherapy still needs to be given in order to prevent
recurrence in lymph nodes.Foss
Ken, I would like to talk in a little more detail about combining
say chemotherapy with radiation therapy when we come back after the
break.  We have to take a short break now for a Medical
Minute. Dr. Kenneth Roberts is speaking with us today about
radiation therapy.Foss
Welcome back to Yale Cancer Center Answers.  This is Dr.
Francine Foss and I am here today with Dr. Ed Chu, my co-host, and
our guest Dr. Kenneth Roberts who joins us to talk about radiation
oncology.  Ken, before the break you gave us a scenario of a
woman with breast cancer who was treated with combined modality
therapy and often times we use radiation in conjunction with other
therapies.  Can you talk about the interaction between say
chemotherapy and radiation therapy?Roberts
Sure, in the case of breast cancer, chemotherapy, or hormone
therapy depending on the circumstances, is used to treat any
potential spread throughout the whole body as well as any disease
that could be localized to the breast or regional lymph nodes, and
radiotherapy is used as a localized treatment, or a local regional
treatment, to treat where there is a higher burden of the
disease and compliment the chemotherapy.  Now, in the case of
breast cancer, we usually give treatments sequentially, often
time's chemotherapy or systemic therapy is given first and then the
radiotherapy later.  There are other circumstances where
clinical trials have shown that giving chemotherapy and radiation
at the same time is of benefit and that there is favorable
interaction between the two modalities where you get an enhanced
killing of tumor cells and hopefully in these circumstances, less
side effects.16:59 into mp3 file 
http://www.yalecancercenter.org/podcast/apr1810-cancer-answers-roberts.mp3Chu
 Are there any cancers where radiation therapy is considered the
treatment of choice upfront, as opposed to combining radiation with
chemotherapy?Roberts
Radiotherapy is the primary treatment for a number of diseases,
certain lymphomas come to mind, and prostrate cancer is another
example, historically.Chu
 That would be early stage prostate cancer?Roberts
Correct, and cervical cancer is another example, although in the
case where we employ radiotherapy as a primary treatment, it's in
more advanced stages or locally advanced instances where surgery is
not feasible.Foss
Ken, we talked a little bit about potential complications of
radiation therapy on normal tissues.  Can you elaborate a
little bit more about that?Roberts
       
 Different normal tissues throughout the body are going to have a
different tolerance for the effects of radiation and the radiation
oncologist has a knowledge base of what each individual clinical
circumstance warrants, what normal tissues are nearby a tumor and
what that normal tissue can tolerate. An example is say a lung
cancer, where one has to be cognizant of how much radiation the
normal lung tissue, or the heart, or the esophagus, the swallowing
tube, can tolerate and that's an important consideration in how we
design radiation and treatment.Foss
I don't think our listeners fully appreciate how much work goes on
behind the scenes in terms of planning these radiation fields and
shielding normal tissues.Roberts
Well it is a considerable amount of work as you appreciate, but in
the planning process for radiotherapy once we have decided that
radiotherapy is going to be part of the treatment plan, a patient
will undergo a planning session for radiotherapy.  Oftentimes
these days, this includes a CAT scan obtained in the radiotherapy
department in the position that the patient is going to be treated
in. That allows us to use some computer systems in which we are
able to simulate how the radiation is going to be delivered, how
the individual beams are going to be oriented, and then how we
might be shaping or blocking each beam in order to minimize just
the normal tissues.  It's a very technologic process these
days and as computers and imaging technologies has been improving
over the last several decades, those advances have been applied to
the field of radiation oncology to the benefit of patients. 
We are able to be much more specific with the delivery of radiation
treatments and be more effective, and I think also produce fewer
side effects.21:00 into mp3 file 
http://www.yalecancercenter.org/podcast/apr1810-cancer-answers-roberts.mp3Chu
 Ken may be you can just review, you know, briefly on what are some
of the common immediate side effects associated with radiation
therapy?Roberts
Sure, and that's highly dependent on what part of the body we are
treating, but as a general concept radiotherapy side effects have
an immediate or an acute phase and the more concerning effects from
radiotherapy are often what could occur many months to years later
in sort of a late phase.  I also should mention that one of
the common things that we do with radiotherapy to reduce side
effects is to break it up into small amounts, given on a daily
basis.  That process of fractionation capitalizes on
differences and how tumors and normal tissues react to radiation
and have a much more specific effect on killing tumor cells and
fewer side effects.  The acute side effects of radiotherapy
often include feeling tired, and skin reactions are common, but it
really depends on specific circumstances and skin reactions have
played an increasingly smaller role in complications of
radiotherapy with modern technologies in the way we are able to aim
the radiation beam.  Otherwise, the acute effects of radiation
have a lot to do with which mucosal surfaces or epithelial surfaces
are nearby what we are treating.Chu
 In general, do people loose their appetite, have nausea, vomiting,
like the total side effects with chemotherapy?Roberts
It really depends on what part of the body is being treated. 
If it is an abdominal site then yes, sometimes we can see nausea
and sometimes we can see diarrhea because of the effects on the
intestines.  Problems with nausea are typically extremely well
controlled with adjunctive medications, anti-nausea medicines, just
as has been seen with chemotherapy, so nausea and vomiting usually
are very controlled and are no longer a limiting factor in cancer
treatment.Foss
Ken, you said that there is a different period of time for each
treatment depending on the disease, but what's the average period
of time that a patient undergoes radiation therapy, for say a solid
tumor like a pancreatic cancer or colon cancer?Roberts
Well for those specific examples of gastrointestinal tumors, when
we are treating with curative intent, usually radiotherapy is being
given as an adjunct along with chemotherapy and surgery and often
times we are looking at roughly a 5 week course of daily
treatments, Monday thru Friday, but another circumstances, say if
the intent is to relieve symptoms or palliate a patient's disease
process, a shorter course of therapy is used since the goals are
much different than trying to cure the patient.  For instance,
if there is a problem with pain or a tumor that is bleeding or
causing obstruction of an airway and causing difficulty breathing,
those are instances where these radiotherapies are very powerful to
relive symptoms and25:13 into mp3 file 
http://www.yalecancercenter.org/podcast/apr1810-cancer-answers-roberts.mp3those treatment courses are typically a lot shorter and might be
anywhere from a week to three weeks, daily treatment.Chu
 A moment ago you mentioned the issue of acute versus long term
side effects of radiation therapy.  I know some of those
long-term consequences can be pretty significant in some patients,
can you tell us a little bit about what some of these long term
side effects people who receive radiation therapy should be aware
of?Roberts
Again, that depends on the exact clinical circumstances. 
Probably a good example to discuss is Hodgkin's disease. 
That's been a highly curable disease and the use of radiotherapy
was employed for the treatment of early stage Hodgkin's disease a
number of decades ago and with the huge success in curing that
particular lymphoma with radiotherapy, we have had many decades of
follow-up to see what the consequences of radiotherapy are. 
For Hodgkin's disease, the way we historically treated it, and no
longer treat it, was to treat a broad volume of lymph nodes
throughout the body and that gave exposures to many different
normal tissues, in what I term a moderate dose range, and while
this cured a vast majority of patients with Hodgkin's disease, what
we saw in the ensuing decade was an increased risk of other cancers
developing and also, when treating the chest area, we saw an
increasing risk for heart disease.  From our experience, we
have changed how we use radiotherapy to not only treat Hodgkin's
disease, but many other diseases, as to learn from that experience
and minimize the risk for future patients.  For Hodgkin's
disease, I must say that there has been a general switch to
chemotherapy as a primary treatment, but still using radiotherapy
in more limited, lower doses, lower volumes of the body to
compliment chemotherapy and give an optimal mix of chemotherapy and
radiation with fewer side effects.Chu
 Just curious, what were those secondary cancers that were
seen?Roberts
Breast cancer has been a particular problem with young women
treated with radiotherapy for Hodgkin's disease decades ago. 
The other types of secondary cancers have included thyroid cancer,
lung cancer, and we are getting some sense that with the change in
how we treat Hodgkin's disease with lower doses of radiation and
chemotherapy that the burden of the risk of other cancers has been
diminishing markedly.Chu
 Presumably, as you say, technologies also have dramatically
improved over the last 5-10 years.Roberts
Absolutely, we are able to much more specifically treat where we
need to and reduce normal tissue exposures.28:58 into mp3 file 
http://www.yalecancercenter.org/podcast/apr1810-cancer-answers-roberts.mp3Chu
 Ken, it has been great having you on the show.  Time ran out
and we did not have a chance to talk about some of the interesting
clinical research that's ongoing at Yale Cancer Center, but
hopefully we will have you back on a future show.Roberts
I will be glad to come back and discuss that.Chu
 Until next week, this is Dr. Ed Chu from Yale Cancer Center
wishing you a safe and healthy week.If you have any questions or would like to share your
comments, visit yalecancercenter.org where you can also subscribe
to our podcast and find written transcripts of past programs. 
I am Bruce Barber and you are listening to the WNPR Health Forum on
the Connecticut Public Broadcasting Network.