Influence of 11C-choline PET/CT on the treatment planning for salvage radiation therapy in patients with biochemical recurrence of prostate cancer

Background and purposeThe present study evaluates the incidence of 11C-choline PET/CT positive findings in patients with recurrent prostate cancer referred for salvage radiotherapy (SRT) and the influence on the definition of the planning target volume (PTV).Material and methodsThirty-seven patients treated with radical prostatectomy and referred to SRT to the prostatic fossa because of biochemical relapse, were analysed retrospectively. All patients underwent 11C-choline PET/CT before radiotherapy. The influence of PET/CT on the extent of the PTV was analysed. The median total follow up after SRT was 51.2 months.Results11/37 (30%) patients had a positive finding in the 11C-choline PET/CT, 5 (13%) outside of the prostatic fossa (iliac lymph nodes), implicating an extension of the PTV. Patients with positive 11C-choline PET/CT had a significant higher PSA value than patients with no pathologic uptake (p = 0.03). Overall, at the end of follow up 56% of the patients had a PSA ⩽ 0.2 ng/ml and 44% had a biochemical relapse of prostate cancer.Conclusions11C-choline PET/CT detects abnormalities outside of the prostatic fossa in 13% of patients referred for SRT because of biochemical relapse after radical prostatectomy, affecting the extent of the PTV. Prospective studies need to be implemented to evaluate the benefit of SRT with a PTV based on 11C-choline PET/CT.