(UroToday.com) The 2026 European Association of Urology (EAU) annual meeting featured a plenary prostate cancer session and a presentation by Dr. Amar Kishan discussing the optimal management of de-novo oligometastatic disease and treating everything we can see with radiotherapy. Dr. Kishan’s discussion was based on a prior case presentation of a 52 year old fit man with ISUP 5 oligometastatic prostate cancer (cT1cN0M1) on conventional imaging. Dr. Kishan started his presentation by defining high volume versus oligometastatic disease based on the CHAARTED definition (for high volume), which is: 4+ bone lesions, with 1+ lesion beyond the vertebral bodies and pelvis (or visceral metastases). Importantly, most definitions of “oligometastatic” do not consider lesion distribution.
In 2025, Unterrainer et al.1 published a retrospective multicenter study to compare the conventional imaging-based disease volume criteria to PSMA PET-based volume definitions in a CHAARTED-like cohort of 67 patients with paired PSMA PET and bone scans. On the basis of conventional imaging, 17 of 67 patients had high volume disease on conventional imaging (25.4%), and 50 of 67 patients had low volume disease on conventional imaging (74.6%). Based on PSMA PET, 27 of 67 patients had high volume disease on PET imaging (40.3%), and 24 of 67 patients had low volume disease on PET imaging (35.8%). In total, 16 of 67 patients (22.4%) had no visible lesion or only locoregional pelvic disease (M0) with PSMA PET. Stage migration between conventional imaging and PSMA PET occurred in 27 of 67 patients (40.3%) by both upstaging and downstaging: 11 of 50 (22%) low volume disease on conventional imaging patients were high volume disease on PET imaging, whereas 1 of 17 (5.9%) high volume disease on conventional imaging and 15 of 50 (30%) of low volume disease on conventional imaging patients were PSMA PET negative:
There are several roles of radiotherapy in high volume disease:
- Prostate primary
- Potential benefit: improved castration resistant free survival, and delaying serious genitourinary events
- Level of evidence: 1, from the PEACE-1 trial2
- Metastatic sites
- Potential benefit: reduce tumor volume (reduced metastasis to metastasis spread)
- Level of evidence: 2b, based on small, single arm phase II trials
Dr. Kishan notes that based on PEACE-1, there is a case for radiotherapy to the primary [2]. In the overall study population, there was an improvement in castration resistance free survival for patients who received standard of care + radiotherapy +/- abiraterone versus patients receiving standard of care +/- abiraterone (HR 0.79, 95% CI 0.69-0.90), of which 57% had high volume disease, and 60% received docetaxel. This benefit was also seen in patients receiving standard of care + abiraterone + radiotherapy versus standard of care + abiraterone (HR 0.79, 95% CI 0.64-0.98):
When assessing time to serious genitourinary events in PEACE-1, a benefit was also noted for patients receiving radiotherapy to the primary:
With regards to the case for radiotherapy to the metastases, Dr. Kishan notes that consolidative treatment in de novo oligometastatic HSPC has less robust data, with two published trials (one of which closed early):
There is an appealing rationale to provide an “off ramp” for systemic therapy, but the appropriate candidates likely need oligometastatic disease by PSMA PET/CT.
Dr. Kishan concluded his presentation discussing the optimal management of de-novo oligometastatic disease and treating everything we can see with radiotherapy, with the following take-home points:
- Radiotherapy to the primary, even in high volume disease, has level 1 evidence for improving castration resistance free survival and time to serious genitourinary adverse events
- Metastasis directed therapy for de novo oligometastatic disease has less robust data, though some early phase data exist to support it as a component of an aggressive plan to provide an eventual off ramp for systemic therapy. Multiple trials are ongoing
- In this young patient with aggressive disease, it is reasonable to offer radiotherapy to the primary and metastasis directed therapy to all sites of disease, in addition to standard of care systemic therapy
Presented by: Amar Kishan, MD, University of California – Los Angeles, CA
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Associate Professor of Urology, Georgia Cancer Center, Wellstar MCG Health, @zklaassen_md on Twitter during the 2026 European Association of Urology (EAU) Annual Meeting, London, United Kingdom, Fri, Mar 13 – Mon, Mar 16, 2026.
References:
- Unterrainer LM, Hope TA, Fendler WP, et al. Low- and high-volume disease in metastatic hormone-sensitive prostate cancer: From CHAARTED to PSMA PET-An International Multicenter Retrospective study. J Nucl Med. 2025 Jan 3;66(1):54-60.
- Fizazi K, Foulon S, Carles J, Roubaud G, et al. Abiraterone plus prednisone added to androgen deprivation therapy and docetaxel in de novo metastatic castration-sensitive prostate cancer (PEACE-1): A multicentre, open-label, randomized, phase 3 study with a 2 x 2 factorial design. Lancet. 2022 Apr 30;399(10336):1695-1707.