LAUSR

Biochemical recurrence after radical therapy for prostate cancer can occur. Prostate-specific membrane antigen (PSMA) positron emission tomography-computed tomography (PET-CT) imaging is increasingly used in salvage therapy. It is also used to triage those who will benefit from salvage radiation treatment (SRT). Emmett et al. [1] examined the value of PSMA informed SRT in improving treatment outcomes in the context of biochemical failure post RP. 164 men with rising PSA post RP with PSA readings between 0.05 and 1.0 ng/ml, considered eligible for SRT at the time of PSMA. PSMA was positive in 61% (n = 102/164): 38/102 in the prostatic fossa, 41/102 in pelvic nodes, and 23/102 distantly [1]. Men with a negative PSMA who received SRT, 85% (n = 23/27) demonstrated a treatment response, compared to further PSA increase in 65% (22/34) in those not treated. This demonstrates, in particular, a negative PSMA PET predicts a high response to salvage fossa radiotherapy. Schiller et al. [2] evaluated the patterns of recurrence after RPE in patients with PC. Thirty-one out of 83 patients (37%) with high-risk PC were the subject of our study. Information from 68Ga-PSMA-PET imaging was used to individualize treatment plans to include suspicious lesions as well as possibly boost sites with tracer uptake in LN or the prostate bed. Compared to negative conventional imaging (CT/MRI), lesions suspicious for PC were detected in 27/31 cases (87.1%) by 68Ga-PSMA-PET imaging, which resulted in changes to the radiation treatment. This demonstrates, compared to conventional CT or MRI staging, PSMA-PET imaging significantly influences radiation planning in recurrent prostate cancer patients. Habl et al. [3] examined 100 patients with biochemical failure after RP and or prior RT who underwent PET/CT or PET/MRI prior to salvage radiotherapy. 80% showed no morphological correlate in the corresponding CT or MRI. 43% of all patients experienced a change in TNM stage due to 68Ga-PSMA-PET imaging. 12% from pN0 to rcN1, 1% from pN0/cM0 to M1a, and 8% from cM0 to M1b. Due to the additional knowledge of 68Ga-PSMA-PET imaging, initial planned RT planning was adapted in 59% of all cases. Albisinni et al. [4] found overall, 68Ga-PSMA PET/CT detected at least one lesion suspicious for prostate cancer in 98/131 (75%) patients. There was an impact on subsequent management in 99/131 patients (76%) including continuing surveillance (withholding hormonal therapy), hormonal manipulations, stereotaxic radiotherapy, salvage radiotherapy, salvage node dissection or salvage local treatment (prostatectomy, high-intensity focussed ultrasound). In conclusion, 68Ga-PSMA PET/CT in patients with prostate cancer with rising PSA after treatment is useful to stratify salvage therapy. 68Ga-PSMA-PET imaging demonstrates a high clinical impact on staging and RT management in patients with biochemically recurrent PC, even at low serum PSA levels. In recurrent prostate cancer after therapy with curative intent, PSMA PET-CT shows encouraging potential for the planning of salvage therapy.