(UroToday.com) The 2023 AUA annual meeting included an advanced prostate cancer session, featuring a presentation by Dr. Daniele Robesti discussing the prognostic role of 68Ga-PSMA PET/CT and the impact of metastasis-directed therapy on cancer progression in men with biochemical recurrence from prostate cancer. Use of 68Ga-PSMA PET is recommended for prostate cancer re-staging in patients with either PSA persistence or biochemical recurrence after radical prostatectomy. Since evidence on the role of metastasis directed therapy on progression-free survival is still poor, Dr. Robesti and colleagues aimed at assessing, in patients with positive PSMA PET, whether metastasis-directed therapy may impact on progression-free survival.
This study retrospectively identified 361 patients evaluated with 68Ga-PSMA PET/CT for biochemical recurrence after radical prostatectomy between 2016 and 2022. Patients were stratified according to PSMA PET results in negative (n=135) and positive (n=226) group. In the latter group, metastasis-directed therapy consisted of stereotactic ablative radiation therapy on positive lesions. Clinical recurrence was defined as any new metastases detected at imaging after a first PSMA PET. Adverse pathological features (i.e. Grade Group 4-5 with ≥pT3a stage and/or lymph node invasion) and salvage treatments were also compared between two groups. Cox regression analyses assessed the impact of a positive PSMA PET and its interaction with metastasis-directed therapy on clinical recurrence after adjusting for PSA level at PSMA PET, number of positive spots and concomitant use of hormonal therapy. Furthermore, multivariable Cox-derived Kaplan-Meier analyses depicted the time from the first PSMA PET to clinical recurrence.
Baseline characteristics of patients included in this study, stratified by negative PSMA PET/CT, positive PSMA PET/CT with metastasis directed therapy, and positive PSMA PET/CT without metastasis directed therapy, are as follows:
Among patients with a positive scan, 113 (31%) received metastasis-directed therapy, and median follow-up was 30 months after PSMA PET. The 3-year clinical recurrence-free survival rates were 72 vs 42% for negative vs positive PSMA PET scan since biochemical recurrence. On Cox analyses, a positive PSMA PET scan was associated with 2-fold higher risk of progression-free survival during follow-up as compared to a negative PSMA PET (HR 2.09, p=0.003) after adjusting for confounders. When testing interaction with use of metastasis-directed therapy in patients with positive PSMA PET, men with positive PSMA PET not receiving metastasis-directed therapy had higher risk of clinical recurrence (HR 2.66, 97.5% CI 1.52-4.66), while such risk was higher but with lesser magnitude in men with positive PSMA PET (HR 1.74, 97.5% CI 1.00-3.02) receiving metastasis-directed therapy as compared to patients with negative PSMA PET. Lastly, on the Cox derived Kaplan-Meier, the 3-year clinical recurrence-free survival rates were:
- 73% in patients with negative PSMA PET
- 51% in patients with positive PSMA PET with metastasis-directed therapy
- 29% in patients with positive PSMA PET without metastasis-directed therapy
Dr. Robesti concluded his presentation discussing the prognostic role of 68Ga-PSMA PET/CT and the impact of metastasis-directed therapy on cancer progression in men with biochemical recurrence from prostate cancer by highlighting the following take-home messages:
- A negative PSMA PET scan represents a protective factor for further metastases during follow-up
- In patients with positive lesions, metastasis-directed therapy significantly improved progression-free survival, but it is still not able to compensate the protective effect of a negative PET PSMA
Presented by: Daniele Robesti, MD, IRCCS San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2023 American Urological Association (AUA) Annual Meeting, Chicago, IL, April 27 – May 1, 2023