Top Line: Prior to PSMA PET, it was difficult to localize sources of biochemical failure after primary radiation for prostate cancer.
The Study: This study combined data from three prospective trials of Ga68 PSMA PET to describe patterns of failure after definitive radiation. Out of 2648 patients included in the 3 trials, they identified 138 who were treated with primary radiation for node negative disease. The most frequent radiation modality was conventionally fractionated EBRT (41%) with the rest receiving a variety of hypofractionation, SBRT, HDR, LDR, or a combination of these. The median time since treatment was 4.3 years, and the median PSA at the time of imaging was 4.8. Of 138 patients imaged, 128 (92.8%) had a positive finding. Of those with a positive PET, 64% had metastatic disease (40% oligometastatic, 24% polymetastatic) and 36% had only intraprostatic disease. However, it wasn’t clear what proportions had nodal metastases or both intraprostatic and extraprostatic disease. Factors associated with extraprostatic recurrence were a higher PSA at the time of recurrence, shorter time since treatment, and the use of ADT during primary treatment.
TBL: Approximately ⅔ of patients with biochemical recurrence after definitive radiation for prostate cancer have metastatic disease outside the prostate on PSMA PET. | Smith, Int J Radiat Oncol Biol Phys 2023
The Study: This study combined data from three prospective trials of Ga68 PSMA PET to describe patterns of failure after definitive radiation. Out of 2648 patients included in the 3 trials, they identified 138 who were treated with primary radiation for node negative disease. The most frequent radiation modality was conventionally fractionated EBRT (41%) with the rest receiving a variety of hypofractionation, SBRT, HDR, LDR, or a combination of these. The median time since treatment was 4.3 years, and the median PSA at the time of imaging was 4.8. Of 138 patients imaged, 128 (92.8%) had a positive finding. Of those with a positive PET, 64% had metastatic disease (40% oligometastatic, 24% polymetastatic) and 36% had only intraprostatic disease. However, it wasn’t clear what proportions had nodal metastases or both intraprostatic and extraprostatic disease. Factors associated with extraprostatic recurrence were a higher PSA at the time of recurrence, shorter time since treatment, and the use of ADT during primary treatment.
TBL: Approximately ⅔ of patients with biochemical recurrence after definitive radiation for prostate cancer have metastatic disease outside the prostate on PSMA PET. | Smith, Int J Radiat Oncol Biol Phys 2023