A Novel Radiographic Pattern Related to Poor Prognosis in Patients with Prostate Cancer with Metastatic Spinal Cord Compression

Abstract

BackgroundProstate cancer spinal bone metastases can have a radiographic profile that mimics multiple myeloma. ObjectiveTo analyse the presence and prognostic value of myeloma-like prostate cancer bone metastases and its relation to known clinical, molecular, and morphological prognostic markers. Design, setting, and participantsA cohort of 110 patients with prostate cancer who underwent surgery for metastatic spinal cord compression (MSCC) was analysed. Spinal bone metastases were classified as myeloma like (n = 20) or non–myeloma like (n = 90) based on magnetic resonance imaging prior to surgery. An immunohistochemical analysis of metastasis samples was performed to assess tumour cell proliferation (percentage of Ki67-positive cells) and the expression levels of prostate-specific antigen (PSA) and androgen receptor (AR). The metastasis subtypes MetA, MetB, and MetC were determined from transcriptomic profiling. Outcome measurements and statistical analysisSurvival curves were compared with the log-rank test. Univariate and multivariate Cox proportional hazard models were used to assess the effects of prognostic variables. Groups were compared using the Mann-Whitney U test for continuous variables and the chi-square test for categorical variables. Results and limitationsPatients with the myeloma-like metastatic pattern had median survival after surgery for MSCC of 1.7 (range 0.1–33) mo, while the median survival period of those with the non–myeloma-like pattern was 13 (range 0–140) mo (p < 0.001). The myeloma-like appearance had an independent prognostic value for the risk of death after MSCC surgery (adjusted hazard ratio 2.4, p = 0.012). Postoperative neurological function was significantly reduced in the myeloma-like group. No association was found between the myeloma-like pattern and morphological markers of known relevance for this patient group: the transcriptomic subtypes MetA, MetB, and MetC; tumour cell proliferation; and AR and PSA expression. ConclusionsA myeloma-like metastatic pattern identifies an important subtype of metastatic prostate cancer associated with poor survival and neurological outcomes after surgery for MSCC. Patient summaryThis study describes a novel radiographic pattern of prostate cancer bone metastases and its relation to poor patient prognosis.