Disease volume (CHAARTED high-volume versus low-volume) and LATITUDE risk

What is measured: how much metastatic disease is present at the start of hormone therapy. How: conventional imaging (bone scan and CT), with CHAARTED high volume defined as visceral metastases or four or more bone lesions with at least one beyond the vertebral column and pelvis, and LATITUDE high risk as two or more of Gleason 8 or higher, three or more bone lesions and visceral disease; de novo (synchronous) presentation is distinguished from metachronous relapse after local therapy because it behaves worse. PSMA PET finds many more lesions, and the volume definitions have not yet been validated on it, so trials such as STAMPEDE still rely on conventional imaging. What a result changes: high-volume disease is treated with androgen deprivation plus docetaxel plus an androgen receptor pathway inhibitor (triplets from PEACE-1 with abiraterone and ARASENS with darolutamide) or with a doublet; low-volume disease gets androgen deprivation plus an androgen receptor pathway inhibitor (enzalutamide in ARCHES and ENZAMET, apalutamide in TITAN, abiraterone in STAMPEDE) plus radiotherapy to the prostate, which improved survival only in low-volume men in STAMPEDE arm H; docetaxel's benefit is confined to high-volume disease in the long-term CHAARTED and GETUG-15 data; metastasis-directed stereotactic radiotherapy is tested for oligometastases; a PSA under 0.2 ng/mL at seven months marks the good responders. Where it matters: metastatic hormone-sensitive prostate cancer.