Use of modern imaging methods to facilitate trials of metastasis-directed therapy for oligometastatic disease in prostate cancer: a consensus recommendation from the EORTC Imaging Group

Abstract

Oligometastatic disease (OMD) represents a clinical and anatomical manifestation between localized and polymetastatic disease. In prostate cancer, as with other cancers, recognition of OMD enables focal, metastases-directed therapies. These therapies potentially shorten or postpone the use of systemic treatment and may delay further metastatic progression, thus increasing overall survival. To validate their efficacy, metastases-directed therapies require imaging methods that definitively recognize OMD and reliably monitor response, particularly to avoid morbidity of inappropriately treating disease subsequently recognized as polymetastatic. This paper reviews current imaging methods used for identifying metastatic prostate cancer at first diagnosis, at biochemical recurrence (BCR), or at the castration resistant stage. Standard imaging methods recommended by current guidelines have insufficient diagnostic accuracy for reliably diagnosing OMD. Modern imaging methods using positron emission tomography /computed tomography (PET/CT) with tumour specific radiotracers (choline or PSMA ligand), and increasingly even whole-body magnetic resonance imaging (WB-MRI) with diffusion-weighted imaging (DWI), allow earlier and more precise identification of metastases. The EORTC Imaging Group suggests clinical algorithms for integrating modern imaging methods into the care pathway at the various stages of prostate cancer in order to identify OMD. Clinical trials utilizing modern imaging methods are proposed for evaluating the benefits of metastasis-directed therapies.

Imaging for Metastasis in Prostate Cancer: A Review of the Literature

“…In patients followed-up for localized PCa, metastases should be sought according to the risk group defined by the National Comprehensive Cancer Network (NCCN) or by the European Association of Urology (EAU) guidelines (6), to estimate the 5year biological relapse risk. These guidelines are heterogeneous across the world.…”

“…About 30% of patients treated radically for high or very high risk PCa have biochemical recurrence (BCR) (39), and with modern imaging, the diagnosis of oligometastatic PCa has become more common (6). Current guidelines from NCCN and EAU (6) but stay heterogeneous across different parts of the world.…”

“…Notably, bone scintigraphy and CT have never been recommended for the majority of patients by experts despite the fact that these methods are still largely included in most clinical guidelines. In another recent consensus statement, provided by the European Organization for Research and Treatment of Cancer (EORTC) imaging group following a review of the role of modern imaging for optimal identification of oligometastatic disease (6), an imaging trial design was proposed.…”

Two cases of oligometastatic castration‐resistant prostate cancer detected by diffusion‐weighted whole‐body imaging with background body signal suppression

“…The therapy has been suggested to be effective at treating prostate cancer patients with oligometastasis . The European Organisation for Research and Treatment of Cancer Imaging Group recommends imaging at a PSA level of 0.2–1.0 ng/mL to exclude multiple metastases and detect oligometastasis for in cases of BCR after RP . Therefore, diagnostic imaging in prostate cancer has become extremely important.…”

“…[2][3][4][5] The European Organisation for Research and Treatment of Cancer Imaging Group recommends imaging at a PSA level of 0.2-1.0 ng/mL to exclude multiple metastases and detect oligometastasis for in cases of BCR after RP. 6 Therefore, diagnostic imaging in prostate cancer has become extremely important. Since 2016, we started using whole-body MRI, especially DWIBS, as a modality to detect metastasis in prostate cancer.…”