As reported in The Lancet Oncology by David Dearnaley, FRCR, and colleagues, the phase III PROMPTS study has shown that a strategy of routine screening with spinal magnetic resonance imaging (MRI) and preemptive treatment to prevent clinical spinal cord compression is likely not warranted in patients with castration-resistant prostate cancer with asymptomatic spinal metastases.
David Dearnaley, FRCR
Study Details
In the open-label multicenter trial, 420 patients no previous spinal cord compression and no spinal MRI in the past 12 months were randomly assigned between February 2013 and April 2017 to receive screening spinal MRI (n = 210) or undergo observation (n = 210). In the MRI group, screening MRI was performed within 4 weeks of random assignment. Patients with MRI positive for radiologic spinal cord compression were offered preemptive treatment with radiotherapy or surgical decompression according to treating physician’s recommendation, with follow-up MRI performed every 6 months after treatment. Patients in both groups were followed every 3 months for 2 years, at 30 and 36 months, and at the time of any clinical spinal cord compression episode. The primary endpoint was time to and incidence of confirmed clinical spinal cord compression in the intention-to-treat population, with the primary timepoint of interest being 1 year after random assignment.
Key Findings
Screening MRI detected radiologic spinal cord compression in 61 (31%) of 200 patients with assessable scans. Preemptive treatment consisted of radiotherapy in 50 of the screen-positive patients.
At data cutoff (April 2020), with a median follow-up of 22 months (interquartile range = 13–31 months), time to clinical spinal cord compression was not significantly improved with screening (hazard ratio = 0.64, 95% confidence interval [CI] = 0.37–1.11, P = .11). The cumulative incidence of clinical spinal cord compression was 6.7% (95% CI = 3.8%–10.6%; 14 patients) in the control group vs 4.3% (95% CI = 2.1%–7.7%; 9 patients) in the MRI screening group at 1 year (difference = –2.4%, 95% CI = –4.2% to 0.1%) and 12.6% (95% CI = 8.5%–17.5%; 26 patients) vs 9.2% (95% CI = 5.8%–13.7%; 19 patients) at 24 months (P = .12). Median time to clinical spinal cord compression was not reached in either group.
In the MRI screening group, patients positive for radiologic spinal cord compression had a higher cumulative incidence of clinical spinal cord compression at 12 months vs screen-negative patients: 7 (11.5%, 95% CI = 5.0%–21.0%) of 61 patients vs 2 (1.3%, 95% CI = 0.2%–4.4%) of 139 patients. At 24 months, the cumulative incidence of clinical spinal cord compression increased to 13.2% (95% CI = 6.1%–23.1%; 8 patients) in the screen-positive group and 7.6% (95% CI = 4.0%–12.6%; 11 patients) in the screen-negative group (P = .13). The incidence of clinical spinal cord compression during the course of the study was lower among screen-negative patients in the MRI group than in the entire control group (P = .042).
The investigators concluded, “Despite the substantial incidence of radiologic spinal cord compression detected in the intervention group, the rate of clinical spinal cord compression in both groups was low at a median of 22 months of follow-up. Routine use of screening MRI and pre-emptive treatment to prevent clinical spinal cord compression is not warranted in patients with asymptomatic castration-resistant prostate cancer with spinal metastasis.”
Emma Hall, PhD, of the Clinical Trials and Statistics Unit, The Institute of Cancer Research, London, is the corresponding author for The Lancet Oncology article.
Disclosure: The study was funded by Cancer Research UK. For full disclosures of the study authors, visit thelancet.com.
