15-year prospective follow-up of patient-reported outcomes of late bowel toxicity after external beam radiotherapy for localized prostate cancer. A comparison with age-matched controls

We have previously described patient-reported outcomes of late side effects induced by conventional external beam radiotherapy (EBRT), 4 and 8 years after treatment, in 181 patients with localized prostate cancer compared with 141 age-matched controls. In the present study, we compare bowel side effects 15 years after EBRT with the same controls, and with the results of our previous 4-year and 8-year follow-ups. Of the 181 patients and 141 controls at the 4-year follow-up, 45 patients (25%) and 79 controls (56%) were still alive at the 15-year follow-up. Bowel symptoms were assessed using the symptom-specific questionnaire Prostate Cancer Symptom Scale (PCSS), which was sent to these 45 patients and 79 age-matched controls with a mean follow-up time of 15 years (162-197 months) after EBRT. The answer frequency was 64% in the patient group and 52% in the control group. The mean age was 78 years in both groups. At the 15-year follow-up, 39% of the patients and 84% of the controls reported no bowel problems (p <0.001), while 16% of the patients and 0% of the controls reported 'Quite a few/many' problems with mucus in the stools (p <0.001). 'Quite a bit/much' stool leakage was reported by 20% of the patients at the 15-year follow-up, in comparison to 4% of the patients at the 4-year follow-up (ns). The proportion of patients reporting late bowel symptoms was unchanged 15 years after EBRT in comparison to the 4-year follow-up. Increased bowel symptoms were seen in patients in comparison to the age-matched controls