title: The use of68Ga-PSMA PET CT in men with biochemical recurrence after definitive treatment of acinar prostate cancer.
abstract: BACKGROUND
  Early localisation of disease recurrence after definitive treatment of prostate cancer is vital to determine suitability for salvage treatment. Our aim was to further investigate the relationship between prostate specific antigen (PSA) level and detection of suspected cancer recurrence using68Ga-PSMA PET/CT in patients with biochemical recurrence after radical prostatectomy (RP) or radiotherapy, particularly at low PSA levels.
  
  
  METHODS
  This retrospective single tertiary referral institution cohort study of men reviewed the results of68Ga-PSMA PET/CT scans for investigation of post RP and post radiotherapy PSA recurrence following primary treatment of prostate cancer. We included men with suspected recurrent prostate cancer based on an elevated post treatment PSA level. The data collected analyzed the relationship of the pre-scan PSA level to the probability of a positive scan finding for recurrent prostate cancer.
  
  
  RESULTS
  Of the cohort of 532 men, 425 had a previous RP and 107 had prior radiotherapy. The median PSA of the RP group was 0.59 ng/mL and 5.8 ng/mL in the radiotherapy group. In the post RP cohort, the detection rate of68Ga-PSMA PET/CT was 11.3% for PSA 0.01 to <0.2 ng/mL, 26.6% for PSA 0.2 to <0.5 ng/mL, 53.3% for PSA 0.5 to <1 ng/mL, 79.1% for PSA 1 to <2 ng/mL and 95.5% for PSA ≥2. Lymph node metastasis post RP was identified in 68% of men with suspected disease recurrence. In the post radiotherapy cohort the detection rate was 33.3% for PSA 0.01 to <0.5 ng/mL, 71.4% for PSA 0.5 to <1 ng/mL, 93.3% for PSA 1 to <2 ng/mL and 100% for PSA ≥2. Local recurrence after radiotherapy was suspected in 71% of the cohort and 40% had suspected lymph node metastasis.
  
  
  CONCLUSIONS
  To our knowledge, this is largest cohort study of detection rates of68Ga-PSMA PET/CT in patients with biochemical recurrence after definitive treatment of prostate cancer, including patients with PSA <0.5 and in a post radiotherapy cohort. Detection of suspected recurrent disease outside the pelvis at low PSA levels will influence the decision for salvage treatment options.
authors.affiliation: Uniting Care Health, Wesley Hospital, Brisbane, Qld, Australia. jyaxley@bigpond.com.
authors.forename: Greta
authors.initials: G
authors.lastname: Meredith
authors.affiliation: Wesley Medical Imaging, Brisbane, Qld, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Wong
authors.affiliation: Uniting Care Health, Wesley Hospital, Brisbane, Qld, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Yaxley
authors.affiliation: Uniting Care Health, Wesley Hospital, Brisbane, Qld, Australia.
authors.forename: Geoff
authors.initials: G
authors.lastname: Coughlin
authors.affiliation: Uniting Care Health, Wesley Hospital, Brisbane, Qld, Australia.
authors.forename: Les
authors.initials: L
authors.lastname: Thompson
authors.affiliation: Uniting Care Health, Wesley Hospital, Brisbane, Qld, Australia.
authors.forename: Boon
authors.initials: B
authors.lastname: Kua
authors.affiliation: Uniting Care Health, Wesley Hospital, Brisbane, Qld, Australia.
authors.forename: Troy
authors.initials: T
authors.lastname: Gianduzzo
mesh_terms: D000368:Aged; D001315:Australia; D005710:Gallium Radioisotopes; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000000981:diagnostic imaging* / Q000473:pathology; D049268:Positron-Emission Tomography; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood / Q000000981:diagnostic imaging* / Q000473:pathology / Q000628:therapy*; D012189:Retrospective Studies; D016879:Salvage Therapy; D016896:Treatment Outcome
chemical_list: D005710:Gallium Radioisotopes; D017430:Prostate-Specific Antigen
keywords: PSMA PET/CT; prostate cancer; recurrence