SBRT vs. EBRT in treatment of painful spine metastases


New data on this topic — from a Phase II/III clinical trial — have just been presented at the virtual annual meeting of the American Society for Radiation Oncology (ASTRO). Basically, the data from this study by Sahgal et al. indicated that 24 Gy (in two 12 Gy doses) of stereotactic body radiation therapy (SBRT) was more effective in the elimination of spinal pain in patients with metastatic cancer as compared to 20 Gy (in five 4 Gy doses) of conventional, external beam radiation therapy (EBRT).

Now we need to be very clear, up front, that not all of the patients in this trial were prostate cancer patients, and it isn’t even clear (at least in the report on the MedPage Today site) how many patients with prostate cancer were included in this study. However, the outcomes from this trial are potentially still of great interest to men with late-stage forms of prostate cancer and associated spinal bone pain.

The study was carried out on patients in Canada and Australasia through the Canadian Cancer Trials Group (CCTG) and the Trans Tasman Radiation Oncology Group (TROG). A total of 229 patients with painful spinal metastases were enrolled between 2016 and 2019 and randomized to either SBRT or standard EBRT. It appears that patients could only have a single “site” of spinal metastasis treated, but a patient could have up to three contiguous spinal segments in the target area for treatment. The patients had to have pain scores of at least 2 on the Brief Pain Inventory and an Eastern Cooperative Oncology Group performance status of 0-2.

Here are the major findings from the study:

  • Average (median) patient ages were
    • 63 years among the SBRT-treated group
    • 65 years among the conventional EBRT-treated group
  • Complete pain relief at 3 months was evident among
    • 35 percent of patients treated with SBRT
    • 15 percent of patients treated with conventional EBRT
    • This difference was statistically significant (P < 0.001)
  • This level of pain relief was sustained at 6 months among
    • 32 percent of patients treated with SBRT
    • 16 percent of patients treated with conventional EBRT
    • This difference was also statistically significant (P = 0.004)
  • With respect to disease control
    • At 3 months of follow-up
      • 92 percent of patients treated with SBRT had no evidence of disease at the treated site
      • 86 percent of patients treated with conventional EBRT had no evidence of disease at the treated site
    • At 6 month of follow-up
      • 75 percent of patients treated with SBRT had no evidence of disease at the treated site
      • 69 percent of patients treated with conventional EBRT had no evidence of disease at the treated site
    • These differences are not statistically significant
  • There was no difference in the overall survival rates between the patients in the two arms of the trial.

What is also very interesting, however, was that, based on associated quality of life survey data, patients clearly did better from a “financial toxicity” perspective when they needed only two courses of treatment (with SBRT) as opposed to five (for conventional EBRT), and these data were again statistically significant.

Now we do need to be cautious about the application of these data to patients with metastatic prostate cancer and associated spinal bone pain, because there are a number of “unanswered” questions in the data as currently available; for example

  • How many of these patients actually had metastatic prostate cancer?
  • Were all these patients on androgen deprivation therapy (ADT) if they had metastatic prostate cancer?
  • How many of the prostate cancer patients had castration-sensitive prostate cancer and how many had castration-resistant prostate cancer?

In an ideal world, one would like to see this trial repeated in a large group of men who only had castration-sensitive and castration-resistant forms of metastatic prostate cancer. However, in the meantime, if you are a patient with significant spinal bone pain and your doctors have been talking to you about radiation therapy to relieve this pain, this is a study you might want to make sure they are aware of.

3 Responses

  1. Anecdotally, most of the men AnCan supports, seeking spot RT for pain relief and disease control, have received SBRT rather than IMRT over the past 18 months or so.

  2. The financial toxicity and pain palliation is even better with a single SBRT dose to bone metastases (not necessarily spinal) :
    https://prostatecancerinfolink.net/2019/08/02/one-large-zap-for-painful-bone-metastases-is-enough/

  3. Great Blog! Thanks for sharing the information.

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