Dose-escalation using intensity-modulated radiotherapy for prostate cancer - evaluation of quality of life with and without (18)F-choline PET-CT detected simultaneous integrated boost.

Background: In comparison to the conventional whole-prostate dose escalation, an integrated boost to the macroscopic malignant lesion might potentially improve tumor control rates without increasing toxicity. Quality of life after radiotherapy (RT) with vs. without (18)F-choline PET-CT detected simultaneous integrated boost (SIB) was prospectively evaluated in this study.

Methods: Whole body image acquisition in supine patient position followed 1 h after injection of 178-355MBq (18)F-choline. SIB was defined by a tumor-to-background uptake value ratio > 2 (GTV(PET)). A dose of 76Gy was prescribed to the prostate (PTV(prostate)) in 2Gy fractions, with or without SIB up to 80Gy. Patients treated with (n = 46) vs. without (n = 21) SIB were surveyed prospectively before (A), at the last day of RT (B) and a median time of two (C) and 19 month (D) after RT to compare QoL changes applying a validated questionnaire (EPIC - expanded prostate cancer index composite).

Results: With a median cut-off standard uptake value (SUV) of 3, a median GTV(PET) of 4.0 cm(3) and PTV(boost) (GTV(PET) with margins) of 17.3 cm(3) was defined. No significant differences were found for patients treated with vs. without SIB regarding urinary and bowel QoL changes at times B, C and D (mean differences ≤3 points for all comparisons). Significantly decreasing acute urinary and bowel score changes (mean changes > 5 points in comparison to baseline level at time A) were found for patients with and without SIB. However, long-term urinary and bowel QoL (time D) did not differ relative to baseline levels - with mean urinary and bowel function score changes < 3 points in both groups (median changes = 0 points). Only sexual function scores decreased significantly (> 5 points) at time D.

Conclusions: Treatment planning with (18)F-choline PET-CT allows a dose escalation to a macroscopic intraprostatic lesion without significantly increasing toxicity.