Photo Credit: Mohammed Haneefa Nizamudeen

For cancer with painful vertebral metastases, dose-intensified SBRT improved 6-month pain scores more effectively than cEBRT, without added toxicity.

Vertebral metastases account for 70% of bone metastases that develop because of cancer progression. Although conventional external beam radiotherapy (cEBRT) remains the standard course of treatment in a multidisciplinary pathway of care, stereotactic body radiotherapy (SBRT) offers some advantages in comparison. SBRT achieves greater precision along with superior dose conformity, providing increased doses of radiation that extend beyond typical spinal cord tolerance.

Potential Advantages

To examine the advantages of SBRT compared with cEBRT in pain reduction experienced by patients with vertebral metastases, Matthias Guckenberger, MD, and colleagues developed an open-label, international, multicenter randomized, phase 3 trial, drawing patient participants from 15 medical centers in Switzerland, Belgium, Germany, Italy, and Poland.

The study’s results were published in Cancer. Dr. Guckenberg wrote in the published findings, “This randomized clinical phase 3 trial aimed to assess whether dose-intensified SBRT would improve longer term pain relief in painful, stable, or potentially unstable vertebral metastases compared with cEBRT.”

Of the 63 patients who met the criteria for acceptance into the study, 33 patients with 36 metastases were allocated to receive SBRT treatment, and 30 patients with 31 metastases were allocated to receive cEBRT treatment. Four patients in the SBRT cohort and one patient in the cEBRT did not receive treatment because they no longer met the study criteria. The median age of all patient participants was 66 years, ranging between 21 to 86. Regarding sex, 78.8% of the SBRT cohort were male, and 43.3% of the cEBRT cohort were male. The most common cancers in each cohort were non-small cell lung cancer (33.3%) and prostate cancer (17.5%).

Pain Reduction

In terms of pain scores at baseline, the mean ± standard deviation for the SBRT cohort was 5.6 ±2.3, and in the cEBRT cohort, it was 4.6 ±2.4. In the SBRT cohort, 81.8% reported moderate-to-severe pain; in the cEBRT, it was 56.7%.

The number of patient participants in the intention-to-treat analysis who experienced pain reduction by at least 2 points at 6 months was 69.4% in the SBRT cohort compared with 41.9% in the cEBRT cohort (two-sided P=0.02); this resulted in a relative risk of 1.7 (95% CI, 1.04–2.64) and an odds ratio of 3.1 (95% CI, 1.2–8.6).

In the SBRT cohort, the patients’ opioid medication use lessened compared to baseline, from 27.2 ±31.1 to 22.1 ±41.5 mg. In the cEBRT cohort, the patients’ opioid medication use increased from 13.5 ±21.4 to 18.6 ±40.0 mg. This difference between the two cohorts was not considered clinically significant (P=0.76).

The rates of complete pain response in the SBRT and cEBRT cohorts at 6 months were similar (22.2% vs 29.0%, respectively, P=0.53). As for pain progression, at 6 months, the SBRT cohort had 22.2% of patients report an increase in pain compared to 41.9% of the cEBRT cohort (P=0.09).

When per-protocol analysis was applied, 78.1% of patients in the SBRT cohort and 43.3% in the cEBRT cohort experienced metastases with pain reduction by at least 2 points after 6 months (two-sided P=0.005). In this analysis, changes in opioid use did not differ in the 6-month period. Complete pain response applying per-protocol analysis in the SBRT cohort was 25% and 30% in the cEBRT cohort (P=0.66).

Neither cohort experienced adverse events with a rating of 4 to 5.

“For patients who have cancer with painful vertebral metastases, dose-intensified SBRT improved pain scores more effectively than cEBRT at 6 months without increasing toxicity,” Dr. Guckenberger and colleagues wrote.