GRACE :: Radiation Oncology

What is SBRT, and which patients are good SBRT candidates?

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SBRT stands for Stereotactic Body Radiation Therapy, a radiation therapy approach which delivers high dose radiation to a target within the body, in either a single treatment session or up to  approximately five treatment sessions (each session is typically referred to as a “fraction”).

The first term in the acronym, “stereotactic” refers to precise three dimensional localization of a tumor target.  The incorporation of the second term in the acronym, “body,” is of historical derivation.  Stereotactic radiation therapy was first invented for the treatment of brain tumors with tools like the Gamma Knife – which has been in practice for a half century.  Extension of stereotactic high-dose radiotherapy techniques to tumor targets outside of the brain and cranium is relatively novel, an advent of the past decade.   Thus the use of the term “body” delineates that the technique is being applied to extracranial (non-brain) tumors.

We have had a few recent questions as to which patients are good candidates for SBRT for lung cancer.  The applications of SBRT for lung cancer grew out of the fact that patients with early stage yet medically inoperable lung cancer had fairly poor outcomes with conventional radiation therapy.  It is in these patients that SBRT trials have been conducted, and in these patients that great success has been shown.

For example, if a patient with an isolated lung cancer (T1, T2, N0) was not able to undergo surgery because of other medical conditions such as heart disease, historically success with conventional external beam radiation therapy  was limited.  With traditional techniques, the chance of locally controlling a cancer such as this was 50% at best.  With SBRT, probability of locally controlling  such a tumor  now exceeds 90%… indeed a dramatic improvement.

SBRT can be used for patients with clinically early stage, solitary, non-small cell lung cancers, measuring as large as 5 to 7 cm.  Size is not the only consideration – location of the primary tumor is important.  Cancers that are largely adherent or close to the chest wall can lead to chest wall pain after therapy.  Radiation oncologists also assess carefully when cancers may be too close to the central structures of the chest and the large airways for SBRT treatment  –  alternative dose and fractionation strategies may be employed to lessen the risk of obstruction of the large airways due to possible inflammation and scarring after treatment.

Is SBRT an option for patients that may otherwise be able to undergo surgery?  That has yet to be established, although clinical trials with medically operable lung cancer are underway and results are pending.


19 Responses to What is SBRT, and which patients are good SBRT candidates?

  • fortmyr says:

    Thank you for this very interesting post Dr. Loiselle. I was not aware that SBRT could be used outside of the brain. Last year, my sister had radiation to her right lung because her bronchi was blocked – I believe that it was radiation of a more conventional type though. I was wondering at what frequency radiations (of any kind) can be done on a same spot, and if it could be successful?

    Thanks again for everything,

    Myriam

  • Dr Loiselle says:

    Hi Myriam –

    Radiation therapy can be repeated. To what extent, what dose, in what time frame, and with what likelihood of success vs. risk depends highly on the patients circumstances.

    Important considerations are: location and size of the tumor, initial radiation dose and fractionation, whether there was a response to the first round of treatment, what other critical anatomic structures are nearby, and their previous and expeted subsequent dose.

    All of these things can be assessed by your sister’s radiation oncologist if necessary.

    Best wishes to you and your sister.

    -Dr. Loiselle

  • fortmyr says:

    Thank you for your answer Dr. Loiselle. It’s comforting to read that re-radiation of the lung could also be done, the more so as having one’s bronchi blocked is not only dangerous but highly uncomfortable.

    A million thanks for all your time and help,

    Myriam

  • Terryl says:

    What a timely topic for me. I am seeing the Rad Onc tomorrow to decide wether or not to proceed with SBRT to a small ( 11mm) pleural lesion that is adjacent to a vertebrae…any special risks with sbrt this close to the spinal column? ( On ct it appears that the lesion is touching the vertebra)

  • Dr Loiselle says:

    In general, when lesions are so small (11mm) SBRT is a great option. Dose to the spinal cord is typically easily controlled to a safe level. When lesions are close to the ribs, there is always some risk for rib/chest wall pain down the road, but it is not a prohibitive risk. Good luck.

    -Dr. Loiselle

  • Terryl says:

    Thanks Dr L, that is exactly what my onc said…but it is always reasuring to hear it again…

  • ssflxl says:

    Dr. Loiselle,

    I am confused by the terms SBRT vs gamma knife, which is also radiation, so are they the same or different modes of radiation.

    thanks

    ssflxl

  • Dr Loiselle says:

    Hi…

    Indeed, SBRT and Gamma Knife are both modes of radiation.

    Gamma Knife however targets only lesions in the brain. SBRT is a general term for targeting lesions outside of the brain with stereotactic radiation…

    -Dr. Loiselle

  • cards7up says:

    I had SBRT to two lesions, one in upper and lower right lobes. No nodal involvement, no mets anywhere else. I have scarring of the pectoral muscle from it, which has it’s own problems. I would do it again if I had to. Thanks for a informational article. Take care, Judy

  • Pingback: Long-Term Recurrences after SBRT: We Haven’t Replaced Lung Cancer Surgery Yet | GRACE :: Lung Cancer

  • reginac says:

    I am having gamma knife radiation to three brain lesions that have shown up–two in the cerebellum and one in the left parietal lobe. But because I’ve been have shoulder pain and swallowing problems, again, they did neck and chest CTs yesterday and discovered that the tumor in the left supraclavicular has grown into my jugular vein and the mediastinal tumor has grown and isolated a segment of my esophagus. Would stereotactic radiation be approopriate in these two situations?

    Thanks.

  • certain spring says:

    Hi Regina. Since the redesign posts are sometimes getting lost so I am giving this a “bump”.
    I need hardly tell you that I am a big fan of radiation, and hope yours goes very well.

  • reginac says:

    I would love it if you could email me and tell me about your experiences, cs: My home email address is reginac23 at msn. com with the symbol used and no spaces. Thanks so much for the encouragement. I really need it right now.

    Regina

  • double trouble says:

    Regina, I’m sorry brain lesions have been found. I hope you sail through your Gamma Knife treatment. And I am so sorry about the supraclavicular and mediastinal growth. Have you chosen a forum where you can post updates? I really want to follow how you’re doing, and will be thinking of you.
    Debra

  • reginac says:

    I post at http://www.moesmisadventures.blogspot.com. Thanks for asking.
    Regina

  • laya d. says:

    Oh my gosh, Regina. . .I just found this thread by accident and had no idea that you were going through all of this. Wow! I’m a little stunned right now, but am very very very hopeful that your radiation treatment is taking care of these new findings. I’m going to pop into your blog to read up some more. . .

    Hang in there, my friend. . .

    Laya

  • fortmyr says:

    Regina, I just saw your comments. I hope that the radiations will take care of your problems. I’ll be thinking about you,

    Myriam

  • Dr West
    Dr West says:

    Regina,

    I’m so sorry that it’s very hard to keep track of the post comments that are coming into so many different sections of the site. I’m monitoring the many forums, but finding the stray comments following posts is very hard to do. I think it would be better to post questions on the forums if you, or anyone, are counting on getting a timely answer.

    I suspect that by this time our potential answers aren’t going to be that helpful, as you’ve probably needed to move forward with some kind of treatment decision. To be honest, I think such extremely individualized case scenarios are very difficult, if not impossible, to answer in the abstract without every detail about a case. There is no clear right answer even for the people directly involved.

    I’ll ask Dr. Loiselle for his thoughts, but I just don’t think that this is a situation in which it would be possible for me to give an answer. This is well beyond a standard treatment in a standard situation.

    Good luck.

    -Dr. West

  • Dr Loiselle says:

    Hi…

    Sorry for the delay in picking up this continued thread.

    Indeed we do use stereotactic radiation in the lung, central chest (“mediastinum”) and adjacent to the esophagus. We also use fractionated external beam techniques. Whether we use a an image guided high dose approach (stereotactic) or a long course with a broader radiation field depends on many of the specifics. For example, if the recurrence is small, adjacent to the spinal canal, or in an area previously treated with radiation therapy, stereotactic techniques are often preferable. Otherwise, in most scenarios, treating with external beam is often favored.

    I hope this helps. Best wishes.

    -Dr. Loiselle

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