Maintaining Mobility May Not Require More Than Single-Dose Radiation

Results from a large, phase 3 trial showed that a single radiation treatment relieves symptoms of spinal cord compression in patients with advanced cancer as effectively as a multifractional course of radiotherapy (RT).¹

At with weeks, 69.5 percent of patients who received single-dose eight GY radiation therapy and 73.3 percent of those who received a total of 20 Gy over five daily treatments could walk normally or with a cane, said the lead author of the SCORAD III study, Peter Hoskin, M.D., F.C.R.P., F.R.C.R., an oncologist at the Mount Vernon Cancer Centre in Middlesex, United Kingdom.

Hoskin discussed results during a press conference June 2 at the 2017 ASCO Annual Meeting, in Chicago. He called the difference in the percentage of patients who could walk “statistically nonsignificant.”

“A single dose of eight Gy is as effective as 20 Gy in five fractions for a range of clinically relevant endpoints, in particular ambulatory status, both at eight weeks and, indeed, at all time points between one week and eight weeks,” he said. “A single dose of radiotherapy, in our minds, is now recommended in this setting and has major advantages for these patients. The important thing to realize, being that these patients have a very short survival—median survival in this study was only 13 weeks—a single dose has enormous advantages in those patients with very short survival times.”

When metastatic cancer spreads to the bones, tumors in the spine can put pressure on the spinal canal, resulting in back pain, numbness, tingling, and difficulty walking. An estimated two-thirds of patients with cancer will develop bone metastases, with breast, prostate, and lung cancers responsible for more than 80% of cases of metastatic bone disease.^1,2 The spine is the most common site for bone metastasis, and 10 percent of all patients with cancer will develop metastatic spinal cord compression.²

There was no significant difference in median overall survival (OS) between the study arms: 12.4 weeks with a single dose vs. 13.7 weeks with five doses. The proportion of patients who experienced severe side effects was similar in the two groups (20.6 percent vs 20.4 percent), but mild side effects were less common in the eight Gy arm (51 percent vs 56.9 percent).

Daniel E. Spratt, M.D., assistant professor of radiation oncology and director of the University of Michigan Spine Oncology Program at the University of Michigan Comprehensive Cancer Center, agreed to review the data for OncLive. Spratt said that although the study was not powered to determine whether the 1.5-week survival advantage favoring the 20 Gy treatment was statistically significant, that extra time could be huge for a patient nearing the end of life.

“The extra four treatments at less than 30 minutes a treatment, two hours total, may be worth an extra 10 days of life to some patients when they are only living 60 days,” he said. “Patients who develop spinal cord compression can have life expectancies >1 year, and eight Gy x 1 has been shown in a prior TROG trial to have very poor durable local control of approximately two to three months.”

From February 2008 to April 2016, 688 patients with metastatic prostate (44 percent), lung (18 percent), breast (11 percent), and gastrointestinal cancers (11 percent) enrolled at centers in the UK and Australia. Median age was 70 years, and 73 percent of patients were male. The researchers randomly assigned patients to receive external beam spinal canal radiation therapy either as a single dose at eight Gy (n = 345) or a total of 20 Gy split in five doses over five days (n = 343).

The primary endpoint was ambulatory status (AS), measured on a four-point scale: 1: Able to walk normally 2: Able to walk with an aid such as a cane or walker 3: Has difficulty walking even with walking aids 4: Dependent on a wheelchair

Two-thirds of patients were at status 1 or 2 at baseline. To be considered non-inferior, the eight GY dose needed to rank within 11 percent of the effectiveness of the longer treatment course when comparing the proportion of patients with AS 1 or 2 at eight weeks, whether maintained from baseline or improved from 3-4 status.

Joshua E. Meyer, MD, associate professor of radiation oncology at Fox Chase Cancer Center, also reviewed the results. He said it is difficult to know how generalizable these results might be because of the short study period.

“The majority of these patients were ambulatory on some level when they were treated, so while patients with more substantial deficits were included, they were in the minority,” he said. “It’s difficult to extrapolate from this to the most severely impacted patients.”

“It’s a very useful study, but there are limitations in the interpretation and I think that eight-week time point is the biggest limitation,” Meyer added. “This is important research. It is moving the field forward to be more patient-centered and doing things more efficiently, which is good not just for the health system but also for the patient being treated.”

References

1. Hoskin P, Misra V, Hopkins K, et al. SCORAD III: Randomized non-inferiority phase III trial of single dose radiotherapy (RT) compared to multifraction RT in patients (pts) with metastatic spinal canal compression (SCC). J Clin Oncol. 35;2017 (suppl; abstr LBA10004).
2. Maccauro G, Spinelli MS, Mauro S, Perisano C, Graci C, Rosa MA. Physiopathology of Spine Metastasis. Int J Surg Oncol. 2011. doi: 10.1155/2011/107969.