Late toxicities of prostate cancer radiotherapy with and without hydrogel SpaceAOR insertion.

ABSTRACT

INTRODUCTION: To investigate whether the implantation of a hydrogel spacer (SpaceOAR) reduces long-term rectal toxicity for prostate cancer patients treated with intensity-modulated radiotherapy (IMRT). METHODS: Patients with localised prostate cancer treated with 81 Gy in 45 fx of IMRT over 9 weeks were retrospectively compared 65 patients with SpaceOAR and 56 patients without SpaceOAR. Planning aims restricted rectal doses to V40 Gy < 35%, V65 Gy < 17%, V75 Gy < 10%. Toxicities were evaluated between 3 months and 3 years after the completion of radiotherapy and were based on the common terminology criteria for adverse events (CTCAE) assessment tool for diarrhoea, haemorrhoids, faecal incontinence and proctitis. RESULTS: The cumulative incidence of low-grade diarrhoea (G1) was significantly higher in the non-SpaceOAR group (21.4% vs 6.2%; P = 0.016). The cumulative incidence of proctitis (grades G1 and G2) was also higher in the non-SpaceOAR group (26.7% vs 9.2%; P = 0.015); the cumulative incidence of G2 proctitis was higher in the latter group (P = 0.043). There were no differences between the treatment groups for cumulative incidences of faecal incontinence and/or haemorrhoids. Three years after IMRT, diarrhoea and proctitis were higher in the non-SpaceOAR group, without reaching statistical significance. This finding was unchanged after correcting for baseline symptoms. CONCLUSION: SpaceOAR is of benefit in reducing the cumulative incidence of low-grade diarrhoea and proctitis for up to 3 years after intensity-modulated radiotherapy.