Intensity-Modulated Salvage Radiotherapy with Simultaneous Integrated Boost for Local Recurrence of Prostate Carcinoma: A Pilot Study on the Place of Pet-Choline for Guiding Target Volume Delineation

Objective: The aim of this study was to report the first cases of salvage radiotherapy (RT) using the intensity-modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) targeted on choline positron emission tomography (PET) uptake in a local recurrent prostate cancer, after a radical prostatectomy.Methods: Four patients received salvage irradiation for biochemical relapse that occurred after the initial radical prostatectomy. The relapse occurred from 10 months to 6 years with PSA levels ranging from 2.35 to 4.86 ng ml(-1). For each patient, an F-18-choline PET-CT showed a focal choline uptake in prostatic fossa, with standardized uptake value calculated on the basis of predicted lean body mass (SUL) max of 3.3-6.8. No involved lymph node or distant metastases were diagnosed. IMRT doses were of 62.7Gy (1.9Gy/fraction, 33 fractions), with a SIB of 69.3Gy (2.1Gy/fraction, 33 fractions) to a PET-guided target volume.Results: Acute toxicities were limited. We observed no gastrointestinal toxicity >= grade 2 and only one grade 2 genitourinary toxicity. At 1-month follow-up evaluation, no complication and a decrease in PSA level (6.8-43.8% of the pre-therapeutic level) were reported. After 4 months, a decrease in PSA level was obtained for all the patients, ranging from 30% to 70%. At a median follow-up of 15 months, PSA level was controlled for all the patients, but one of them experienced a distant lymph node recurrence.Conclusion: Salvage irradiation to the prostate bed with SIB guided by PET-CT is feasible, with biological efficacy and no major acute toxicity.Advances in knowledge: IMRT with PET-oriented SIB for salvage treatment of prostate cancer is possible, without major acute toxicity.