Patterns of relapse as determined by 68Ga-PSMA ligand PET/CT after radical prostatectomy : Importance for tailoring and individualizing treatment

Strahlenther Onkol. 2018 Apr;194(4):303-310. doi: 10.1007/s00066-017-1231-9. Epub 2017 Nov 13.

Abstract

Purpose: To evaluate the patterns of relapse and impact on the intended treatment when using 68Ga-prostate-specific membrane antigen (PSMA) ligand positron emission tomography/computed tomography (PET/CT) imaging for restaging of disease in patients with biochemical relapse after radical prostatectomy (RP) before salvage radiotherapy (sRT).

Methods: In all, 39 patients with biochemical recurrence after RP who had no primary indication for adjuvant RT due to the absence of biologically unfavorable disease (e.g., extracapsular extension, seminal vesicle invasion, positive margins, or lymph node involvement) underwent a 68Ga-PSMA ligand PET/CT for planning of sRT.

Results: PET/CT was positive in 84.6% (33/39) of patients. A total of 61 lesions were observed in these patients (on average 1.8 lesions per patient); 30.3% (10/33) of patients had locally recurrent disease in the prostatic bed. The clinical TNM stage (TNM: tumour-lymph nodes-metastasis-classification) was altered in 69.7% (23/33) of patients following PET, resulting in individualized treatment concepts. A prostate-specific antigen (PSA) >1.0 ng/mL was significantly associated with an increased risk of extrapelvic metastatic disease (p = 0.048). The PSA level at the time of PSMA ligand PET/CT correlated with the peak standardized uptake value (SUVpeak; p = 0.002). According to current clinical guidelines, the remaining 15.4% (6/39) of patients without evidence of disease on PET received sRT with a dose of 66.0 Gy.

Conclusion: Our results suggest that in patients with biochemical recurrence who did not receive early sRT, a 68Ga-PSMA ligand PET/CT for restaging of disease allows for tailoring and individualizing treatment. Particularly in patients with PSA levels above 1.0 ng/mL, a 68Ga-PSMA ligand PET/CT should be performed for therapy planning, since patients often have metastases not confined to the pelvis.

Keywords: Computed tomography; Individualized treatment; Positron emission tomography; Prostate cancer; Prostate-specific membrane antigen ligand.

MeSH terms

  • Aged
  • Antigens, Surface*
  • Gallium Radioisotopes*
  • Glutamate Carboxypeptidase II*
  • Humans
  • Lymph Node Excision
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Neoplasm Recurrence, Local / diagnostic imaging*
  • Neoplasm Recurrence, Local / pathology
  • Neoplasm Recurrence, Local / radiotherapy
  • Neoplasm Staging
  • Positron Emission Tomography Computed Tomography*
  • Precision Medicine*
  • Prostatectomy*
  • Prostatic Neoplasms / diagnostic imaging*
  • Prostatic Neoplasms / pathology
  • Prostatic Neoplasms / radiotherapy
  • Prostatic Neoplasms / surgery*
  • Radiotherapy, Adjuvant
  • Salvage Therapy*

Substances

  • Antigens, Surface
  • Gallium Radioisotopes
  • Gallium-68
  • FOLH1 protein, human
  • Glutamate Carboxypeptidase II