title: Delineating biochemical failure with68Ga-PSMA-PET following definitive external beam radiation treatment for prostate cancer.
abstract: We investigated the role of68Ga-PSMA-PET (PSMA) to determine the location of disease recurrence in those with a rising PSA following definitive external beam radiation treatment (EBRT).
  
  
  
  538men were treated with image guided EBRT to a dose of 78 or 82Gy between 2007 and 2014. Patients at least 24months post EBRT with biochemical failure (nadir+2) underwent PSMA scanning. Local recurrence (LR) was defined as increased uptake within the prostate or seminal vesicles. Distant disease included lymph node (LN), bone or visceral metastases.
  
  
  
  419men formed the study cohort. Median follow-up was 50months, 70 patients (17%) had biochemical failure (BF), 13 of whom have died. Of the 57 survivors, 5 had metastases detected on conventional scans; 2 were lost to follow up. 48men (of 50 candidates) underwent PSMA; in all cases, the PSMA was unequivocally positive. Of the 48 positive scans, 25 patients (52%) failed beyond the prostate - 5 in bones, 16LN, 3 in both, and 1 in the lungs. Fifteen men (31%) failed within the gland and in either LN (11), bones (3), or both (1). Eight (17%) had an isolated LR, which represents 2% of patients managed with definitive EBRT and followed for at least 2years.
  
  
  
  PSMA was positive in all patients with BF. Site of failure following dose-escalated EBRT was generally distant. Isolated LR (on PSMA) occurred in only 8 of 419 patients post-EBRT.
authors.affiliation: Department of Radiation Oncology, Royal North Shore Hospital, Australia; University of Sydney, Sydney, Australia; Genesis Cancer Care, Sydney, Australia. Electronic address: george.hruby@health.nsw.gov.au.
authors.forename: George
authors.initials: G
authors.lastname: Hruby
authors.affiliation: Department of Radiation Oncology, Royal North Shore Hospital, Australia; University of Sydney, Sydney, Australia; Genesis Cancer Care, Sydney, Australia.
authors.forename: Thomas
authors.initials: T
authors.lastname: Eade
authors.affiliation: Department of Radiation Oncology, Royal North Shore Hospital, Australia; University of Sydney, Sydney, Australia; Genesis Cancer Care, Sydney, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Kneebone
authors.affiliation: University of New South Wales, Sydney, Australia.
authors.forename: Louise
authors.initials: L
authors.lastname: Emmett
authors.affiliation: Department of Radiation Oncology, Royal North Shore Hospital, Australia.
authors.forename: Lesley
authors.initials: L
authors.lastname: Guo
authors.affiliation: Department of Nuclear Medicine, St Vincent's Hospital, Australia; University of New South Wales, Sydney, Australia.
authors.forename: Bao
authors.initials: B
authors.lastname: Ho
authors.affiliation: Department of Nuclear Medicine and PET, Royal North Shore Hospital, Australia.
authors.forename: Ed
authors.initials: E
authors.lastname: Hsiao
authors.affiliation: Department of Nuclear Medicine and PET, Royal North Shore Hospital, Australia.
authors.forename: Geoff
authors.initials: G
authors.lastname: Schembri
authors.affiliation: Department of Radiation Oncology, Royal North Shore Hospital, Australia.
authors.forename: Julia
authors.initials: J
authors.lastname: Hunter
authors.affiliation: Department of Radiation Oncology, Royal North Shore Hospital, Australia.
authors.forename: Carol
authors.initials: C
authors.lastname: Kwong
mesh_terms: D015331:Cohort Studies; D004492:Edetic Acid / Q000031:analogs & derivatives*; D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging*; D009842:Oligopeptides; D049268:Positron-Emission Tomography / Q000379:methods*; D011467:Prostate / Q000000981:diagnostic imaging; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D017211:Treatment Failure
chemical_list: D005709:Gallium Isotopes; D005710:Gallium Radioisotopes; D009842:Oligopeptides; C000718244:gallium 68 PSMA-11; D004492:Edetic Acid
keywords: Biochemical failure; PSMA-PET; Prostate cancer