What is the appropriate margin for focal therapy of prostate cancer when using MRI/MRSI for treatment planning? Proposed secondary study for ACRIN 6659 data Fergus Coakley MD, Professor of Radiology and Urology, Chief, Abdominal Imaging, University of California San Francisco Objective Determine the appropriate margin for focal therapy of prostate cancer when planned from MRI/MRSI Background Increasing interest in focal therapy as “middle way” for prostate cancer treatment – Active surveillance – minimalist – Definitive treatment (RRP or RT) – high morbidity Three requirements for focal therapy: – Clinical selection – no consensus – Radiological selection – MRI criteria on next slide – Adequate margin – purpose of this proposal UCSF selection study 88 patients with MRI/MRSI before RRP and with detailed tumor maps – MRI/MRSI reviewed by two independent readers – Dominant treatable foci = largest lesion & > 0.5cc Results: – ALL visible lesions on T2 with ≥0.54 cm 3 of concordant MRSI abnormality (n = 27 and 25 for reader 1 and 2, respectively) were correctly identified dominant treatable tumor foci Proposal (two steps) Apply UCSF criteria to ACRIN database – T2 visible & ≥0.54 cm3 concordant MRSI – Two readers (remote or travel to ACRIN HQ?) – Anticipate small number will meet criteria (<10?) Co-register digital pathology with T2 – Pick largest/best T2 image and “best match” pathology slide – Morph gland outline on pathology to T2 (allows margin measurement using MRI calipers) – Measure maximum margin (per quadrant and separate capsular from non-capsular?) Example “Best match” T2 MRI and pathology slice Example “Morph” pathology to T2 Example “Morph” pathology to T2 Example Measure margins – maximum capsular and non-capsular plus by quadrant? Analysis Presumably will be essentially descriptive – what margin would have encompassed all the tumors? Issues for discussion: – Explore additional selection criteria? – More than two reads? – Can readings be done remotely? – Who will fuse images and measure margins? – Funding level? Travel and/or time?