Cranberry capsules are not superior to placebo capsules in managing acute non-haemorrhagic radiation cystitis in prostate cancer patients: a phase III double blinded randomised placebo controlled clinical trial.

Acute radiation cystitis affects the quality of life of many prostate cancer patients. A previous pilot study suggested that cranberry capsules may decrease some of the symptoms of acute radiation cystitis. Here we further test their effectiveness in a multicentre double blinded placebo-controlled clinical trial.A total of 108 prostate cancer patients were recruited at three New Zealand hospitals between September 2016 and January 2019. Out of this cohort, 101 patients provided datasets for analysis (51 men on cranberry capsules and 50 men on beetroot-containing placebo capsules). Patients took two capsules each morning during RT and for 2 weeks after completion of RT. Three measures were used to assess cystitis severity: modified RTOG, O'Leary interstitial cystitis scale and a sensitive novel radiation induced cystitis assessment scale (RICAS). Cystitis severity was scored at baseline and weekly thereafter during RT and for two weeks after completion of RT. Radiation protocols were stratified to conventional fractionation or hypo-fractionated radiation therapy (CHHiP) to the prostate or radiation to the prostate bed.Cranberry capsules performed significantly worse than placebo capsules with respect to day time frequency and bladder control, using the more sensitive RICAS scale. No significant difference in cystitis severity was seen between patients receiving hypofractionation and those receiving conventional fractionation to the prostate gland.Cranberry capsules were not superior to beetroot-containing placebo capsules in managing radiation cystitis in our prostate patient cohort. RICAS may be a useful tool for measuring radiation cystitis in future studies.