Main Session
Sep 30
PQA 07 - Genitourinary Cancer, Patient Safety, Nursing/Supportive Care

3192 - PSA and PSMA Kinetics for Intermediate Risk, High- Very High Risk and Oligometastatic Prostate Cancer Patients Treated by Moderate Hypofractionated Radiotherapy (MHRT) and SBRT with Androgen Deprivation Therapy (ADT): A Single Center Prospective Database

12:45pm - 02:00pm PT
Hall F
Screen: 9
POSTER

Presenter(s)

Trinanjan Basu, MD Headshot
Trinanjan Basu, MD - HCG Cancer Center, Mumbai, Maharashtra

T. Basu1, J. P. Sahu1, S. Kamat1, R. R. Menon1, G. Roshan1, R. Nair1, S. Gawde2, A. U. Gadekar1, D. Kurkure Jr1, P. Modi1, and K. Parwani1; 1Department of Radiation Oncology-HCG Cancer Centre, Mumbai, India, 2Department of Nuclear Medicine-HCG Cancer Center, Mumbai, India

Purpose/Objective(s):

The curative intent radiotherapy (RT) for intermediate risk to oligometastatic prostate cancer along with ADT is one of the widely used treatment modality. The kinetics of PSA and PSMA PETCT and the correlation of MHRT and SBRT is less reported. The aim of this study was to assess the kinetics of PSA and PSMA PETCT in prostate cancer treated by ADT and MHRT/SBRT.

Materials/Methods:

This was a single center prospective database analysis of intermediate, high, very high risk and oligometastatic (IR, HR, VHR, OM) prostate cancer patients treated by ADT and either MHRT or SBRT as part of radical radiotherapy. ADT was neoadjuvant, concurrent and adjuvant depending on risk category. MHRT schedule was 60-62 Gy/20 fractions /4 weeks and SBRT 36.25 Gy/25 Gy in 5 fractions over 2 weeks. All HR onwards patients received pelvic nodal RT as well and in OM scenario to metastatic site as well. Treatment was linac based 6MV FFF with 6D couch correction. Strict bladder/rectal protocol was maintained. Patients had baseline, pre RT and post treatment every 3 months serum PSA estimation. We included patients with baseline PSMA PETCT scan and at least one post MHRT/SBRT. The baseline and post MHRT/SBRT SUVMax were documented as per EANM criterion. PSA level post MHRT/SBRT for biochemical control was defined as per phoenix criteria.

Results:

95 patients between January 2018 to June 2024 were analysed. Majority were HR (53%) and predominant Gleason grade group 4 (52.2%). Median age was 71 years and median follow up 30 months. 35 patients received MHRT and 60 patients received SBRT. At baseline, median PSA was 21.8 ng/ml and median SUVmax of PSMA PETCT was 11.4 (Prostate), 7.2 (nodes) and 4.7 (OM site) respectively. Pre RT and post neoadjuvant ADT, median PSA was 1.2 (MHRT) and 0.8 (SBRT) respectively. At 3 months post RT, median PSA was 0.06 (SBRT) and 0.08 (MHRT). Median time of 1st post RT PSMA PETCT was 10 months (range: 6-15 months) with median SUVmax of 5.06 (Prostate), 1.1 (nodes) and 2.2 (OM) respectively. The median SUVMax PETCT in prostate was 3.5 (MHRT) and 3.1 (SBRT) respectively. The median time to complete metabolic resolution among available patients with serial PSMA was 26 months. Till last follow 89.5% were biochemically controlled with median PSA of 0.01ng/ml. 10 patients (MHRT:6, SBRT:4) had disease progression predominant in bones (8) and local (2).

Conclusion:

PSA response precedes PSMA SUVmax in both MHRT and SBRT cohort. The SUVmax of prostate decreases gradually over one year and stable SUVmax in prostate beyond one year indicates local recurrence. Metastatic disease showed rising PSA in concordance to PSMA PETCT. Future analysis as per MHRT/SBRT with PSA and PSMA kinetics might predict superiority of one over the other.