Impact of 18F-Choline PET/CT in the Decision-Making Strategy of Treatment Volumes in Definitive Prostate Cancer Volumetric Modulated Radiation Therapy.

Introduction: Aim of the study is to evaluate the impact of Cho-PET/CT in decision-making strategy of patients with localized prostate cancer (PC) eligible to definitive radiotherapy (RT).

Materials And Methods: Sixty patients Cho-PET/CT before RT were prospectively enrolled. All patients were treated with volumetric modulated arc therapy with simultaneous integrated boost in 28 fractions. Androgen deprivation therapy was prescribed according to National Comprehensive Cancer Network (NCCN) risk classification. Therapeutic strategy based on the Cho-PET/CT evaluation was compared with the strategy that would have been proposed in case of PET not available and/or not strictly indicated, according to international and national PC guidelines.

Results: Cho-PET/CT was positive in 57 cases (95%): T in 45 (79%); T in combination with N in 8 (14%); and M (bone) in combination with T or N, or both, in 4 (7%). After Cho-PET/CT, patients were stratified as follows: 26 (43%) low risk, 10 (16%) intermediate risk, and 24 (41%) high risk. Cho-PET/CT shifted treatment indication in 13 cases (21%). The changes regarding radiation treatment volumes were as follows: 6 intermediate risk (10%) shifted to high risk and consequently were irradiated on prostate, seminal vesicles, and pelvic nodes PTVs; in 7 high risk (11%), the Cho-PET/CT showed bone and/or N uptake, and consequently, a simultaneous integrated boost on PET positive sites was prescribed.

Conclusions: Cho-PET/CT seems to be a promising diagnostic tool in patients who are candidates for radical RT and supporting the decision making in treatment planning, in particular in intermediate-high risk.