Should 4 Gy x 5 be the standard of care for spinal cord compression in patients with poor prognosis?

The randomized SCORE-2 trial demonstrated equivalent survival (median 3 vs 3.7 months), response rates (72% vs 74% ambulatory at 1 month), and durability of palliation (~80% of survivors ambulatory at 6 months in both arms) between 4 Gy x 5 and 3 Gy x 10 when treating cord compression in patients with poor prognosis, as defined by a validated prognostic scoring system. Given that one extra week of RT is a significant investment for those with only 3-4 months median survival, should 4 Gy x 5 be the standard of care in this patient population?

1 Answer

Mednet Member

Radiation Oncology · Michigan Healthcare Professionals, PC

Answered on

Wow, so this question was asked in 2016 and nobody has taken a whack at it.

30 Gy in 10 fx has been the long-standing standard dose for SCC in most countries for just about ever. This has not been compared to other doses until more recently. 30/10 works well, is relatively short (2 weeks), and utilizes fractionation to hopefully allow for reduction in mass effect. I've used it the vast majority of times I have had patients with spinal cord compression, with results equal to what is seen in the literature.

The study mentioned above - SCORES-2 - looks at patients with poor prognosis, so life expectancy is thought to be limited. They compared 20/5 and 30/10. Note that this is not an "improving outcomes" study. This is a "hopefully this isn't worse study" - i.e. non-inferiority. As our specialty has an infatuation with reducing treatment times without improving cancer or QOL outcomes, these types of studies remain common.

They had 100 patients or so in each arm and there was essentially no benefit in any of the outcomes. The conclusion is that it's good enough. I think it is perfectly reasonable to give 20/5 in lieu of 30/10 for poor prognosis patients. However, physicians are poor at predicting prognosis and this is all subjective. In addition, insurance companies allow 30 in 10 for all patients, regardless of PS, so the practice has not changed much and 30 in 10 remains king nationally.

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Now, we are in 2023, several years later. We note that SBRT improves pain control for bone metastases. We use many high-dose/short-course treatment plans, to increase BED and to hopefully improve outcomes/decrease toxicity. Unfortunately, the one SBRT cord compression study (RTOG 0631) failed to improve outcomes. Interestingly, this was an American study that: 1) used 8 Gy/1 for the control arm - a dose that is sparingly used in our country 2) designed it as a superiority trial (hmm...). The pain control was better in the 8 Gy in 1 arm, as compared to 16-18/1 (60% vs 40%). No other outcome was different. This is contradictory to MDACC study and Canadian study for bone met SBRT that showed improved pain control. The Canadian study looked at spinal metatases (solely) but not cord compression and compared 24/2 to 20/5 and the SBRT arm and showed that the patients treated with SBRT had a much higher probability of complete pain relief (35% vs 14%).

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Perhaps cord compression is vastly different as compared to painful bone metastases in the spine (not everyone agrees - if you look at palliative RO textbooks, they are treated very similarly with regards to dose options).

Sometimes the study outcomes are random chance (if p=0.05, still a 5% chance the interventions aren't truly different), sometimes they don't replicate. We have multiple decades and hundreds of thousands of patients treated with 30 in 10 and a 200 person trial saying that 20 in 5 isn't worse. I don't know that I would use that study to change practice that has worked quite well for many years for many patients. People trust their gut, and occasionally their gut may be right. They may look at BED and feel that 20 in 5 is too low. Maybe they aren't sure about the prognosis of patient and with new systemics/immunotherapy, the potentially poor prognosis patient doesn't have as quite poor prognosis as thought. If saving a week is that important, I think it is worth the time to discuss with the patient that 1 week is likely not worse, certainly isn't better and the only benefit noted is saving a week (and money, of course).

I tend to do 3-5 fractions, but I also tend to deliver a higher dose and I do it conformally with IMRT/SBRT techniques. I do not use single fraction if there is a mass (I still believe in the Rs of radiobiology). I use 24/3 or 30/5 or 25/5 (if larger volume - but I don't have a heuristic - just go by 'feel'). I know this is unorthodox, but it's a synthesis of the studies we have for both cord compression and bone metastases (which I think actually do share similarities).

I am curious to see what others say.