Marieke van Son

132 CHAPTER 7 Figure 2 – Predicted probabilities of grade ≥2 GU toxicity or ED at various levels of each risk factor. Modelled marginal means and their confidence intervals are shown, holding the other variables in the model constant. DISCUSSION For patients with a local prostate cancer recurrence after radiotherapy, the tradeoff between tumor control and risk of normal tissue damage needs close evaluation when offering salvage treatment. This study provides a comprehensive insight into the oc- currence of toxicity after ultrafocal salvage HDR-BT. While severe (grade 3) toxicity was very low (3% GU, 0% GI), proving the safety of this treatment, the number of patients ex- periencing mild (grade 1) or moderate (grade 2) toxicity was more pronounced (GU 32% and 41%, GI 31% and 5%, respectively). Although almost half of all patients already had grade ≥2 ED at baseline, new grade 2 and 3 ED was seen in 22% and 15%, respectively. A further evaluation of individual toxicity subdomains and timing of occurrence shows that there are certain patterns of toxicity over time. The acute phase after treatment