medwireNews: Magnetic resonance imaging (MRI) screening plus pre-emptive treatment does not significantly reduce clinical spinal cord compression (SCC) rates in patients with castration-resistant prostate cancer (CRPC) and spinal metastasis, PROMPTS trial data show.
Writing in The Lancet Oncology, Emma Hall (The Institute of Cancer Research, London, UK) and co-authors say that they “do not recommend screening spinal MRI in unselected patients with castration-resistant metastatic prostate cancer, but further research to identify high-risk groups is warranted.”
The phase 3 study included 420 patients (median age 74 years) with metastatic (m)CRPC and asymptomatic spinal metastasis who were randomly assigned to undergo screening spinal MRI (n=210) or to no MRI (n=210).
Using an MRI epidural spinal cord compression (ESCC) scale, the researchers identified radiologic SCC in 31% of 200 patients with assessable scans in the intervention group.
Of these 61 patients, 43% had maximum ESCC scores of 1a indicating impingement without deformation, 28% had a maximum score of 1b with deformation of the thecal sac, and 20% were 1c with deformation of the thecal sac and spinal cord abutment but not compression. A further 3% had a score of 2 and 7% had a score of 3, indicating SCC with or without visible cerebral spinal fluid, respectively.
The majority (82%) of the patients with radiologic SCC were given pre-emptive radiotherapy and 46% received corticosteroids.
At 1-year postrandomization, 4.3% of participants in the intervention group and 6.7% of those in the control group had clinical SCC, a nonsignificant difference.
Furthermore, after a median 22 months of follow-up, there was no significant difference in the time to clinical SCC between the two arms.
However, the researchers note that the 12-month clinical SCC rate was 11.5% in the screen-positive patients versus 1.3% in those who were negative for SCC on MRI, and the cumulative incidence of clinical SCC during the course of the study was significantly higher in the screen-positive than the screen-negative group.
The investigators also report that they were unable to identify any variables that predicted the development of either radiologic or clinical SCC.
Hall et al conclude: “MRI screen-detected early [radiographic] SCC does not always progress to [clinical] SCC with contemporary systemic management of castration-resistant prostate cancer and observation might be sufficient for ESCC grade 1a–b [radiographic] SCC.”
However, they add that “particular vigilance is recommended for these patients with a low threshold for recommending spinal MRI if any new back pain manifests because they are at substantial risk of developing new sites of [clinical] SCC.”
In an accompanying comment, Shankar Siva (Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia) and co-authors say that “the PROMPTS trial has highlighted some important clinical practice principles: (1) adherence to clinical guidelines results in good functional outcomes in patients with clinical suspicion of SCC; (2) patients with a diagnosis of SCC are at increased risk of subsequent SCC at other sites and should be considered for more rigorous and closer clinical follow-up to prompt early detection; and (3) low-dose radiotherapy is effective at preventing radiological and clinical progression of asymptomatic SCC.”
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Lancet Oncol 2022; doi:10.1016/ S1470-2045(22)00092-4
Lancet Oncol 2022: doi:10.1016/S1470-2045(22)00140-1