Toxicity outcome in patients treated with modulated arc radiotherapy for localized prostate cancer

Abstract

Aim

This study evaluates the acute toxicity outcome in patients treated with RapidArc for localized prostate cancer.

Background

Modern technologies allow the delivery of high doses to the prostate while lowering the dose to the neighbouring organs at risk. Whether this dosimetric advantage translates into clinical benefit is not well known.

Materials and methods

Between December 2009 and May 2012, 45 patients with primary prostate adenocarcinoma were treated using RapidArc. All patients received 1.8[[ce:hsp sp="0.25"/]]Gy per fraction, the median dose to the prostate gland, seminal vesicles, pelvic lymph nodes and surgical bed was 80[[ce:hsp sp="0.25"/]]Gy (range, 77.4–81[[ce:hsp sp="0.25"/]]Gy), 50.4[[ce:hsp sp="0.25"/]]Gy, 50.4[[ce:hsp sp="0.25"/]]Gy and 77.4[[ce:hsp sp="0.25"/]]Gy (range, 75.6–79.2[[ce:hsp sp="0.25"/]]Gy), respectively.

Results

The time between the last session and the last treatment follow up was a median of 10 months (range, 3–24 months). The incidence of grade 3 acute gastrointestinal (GI) and genitourinary (GU) toxicity was 2.2% and 15.5%, respectively. Grade 2 acute GI and GU toxicity occurred in 30% and 27% of patients, respectively. No grade 4 acute GI and GU toxicity were observed. Older patients (>median) or patients with V60 higher than 35% had significantly higher rates of grade ≥2 acute GI toxicity compared with the younger ones.

Conclusions

RapidArc in the treatment of localized prostate cancer is tolerated well with no Grade >3 GI and GU toxicities. Older patients or patients with higher V60 had significantly higher rates of grade ≥2 acute GI toxicity. Further research is necessary to assess definitive late toxicity and tumour control outcome.