High-dose intensity-modulated radiotherapy for prostate cancer using daily fiducial marker-based position verification: acute and late toxicity in 331 patients.

We evaluated the acute and late toxicity after high-dose intensity-modulated radiotherapy (IMRT) with fiducial marker-based position verification for prostate cancer. Between 2001 and 2004, 331 patients with prostate cancer received 76 Gy in 35 fractions using IMRT combined with fiducial marker-based position verification. The symptoms before treatment (pre-treatment) and weekly during treatment (acute toxicity) were scored using the Common Toxicity Criteria (CTC). The goal was to score late toxicity according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer (RTOG/EORTC) scale with a follow-up time of at least three years. Twenty-two percent of the patients experienced pre-treatment grade ≥ 2 genitourinary (GU) complaints and 2% experienced grade 2 gastrointestinal (GI) complaints. Acute grade 2 GU and GI toxicity occurred in 47% and 30%, respectively. Only 3% of the patients developed acute grade 3 GU and no grade ≥ 3 GI toxicity occurred. After a mean follow-up time of 47 months with a minimum of 31 months for all patients, the incidence of late grade 2 GU and GI toxicity was 21% and 9%, respectively. Grade ≥ 3 GU and GI toxicity rates were 4% and 1%, respectively, including one patient with a rectal fistula and one patient with a severe hemorrhagic cystitis (both grade 4). In conclusion, high-dose intensity-modulated radiotherapy with fiducial marker-based position verification is well tolerated. The low grade ≥ 3 toxicity allows further dose escalation if the same dose constraints for the organs at risk will be used.