Radiation cystitis (RC) and radiation proctitis (RP) are common complications of radiotherapy (RT) in patients with prostate cancer, each with a 10-year cumulative incidence of ≥20 percent, according to researchers from the Chinese University of Hong Kong.
“RC and RP are two well-recognized RT-related complications with variable and somewhat unpredictable severity and clinical course,” wrote the researchers. “Their true incidence remains unclear because there is no consensus regarding definitions and reporting methodologies in the literature.” [Hong Kong Med J 2026;32:225-233]
In a retrospective study, 762 male patients (mean age, 70 years) who underwent primary RT for localized prostate cancer and low-volume metastatic hormone-sensitive prostate cancer, as well as salvage or adjuvant RT after prostatectomy between 2001 and 2023 were followed for a median of 59 months to evaluate the cumulative incidence of RC and RP.
5- & 10-year incidence
The cumulative incidence was 11 percent for RC and 20 percent for RP at 5 years, rising to 20 percent and 20.6 percent, respectively, at 10 years.
The median onset time of RC was 32.5 months, with 25 percent of cases first presenting beyond 5 years after RT completion. “In contrast, RP tended to present earlier, with a median time to onset of 22.5 months, and the cumulative incidence approached a plateau at 5 years,” reported the researchers.
Severe (grade ≥3) RC occurred in 6.3 percent of patients at 5 years and rose to 12 percent at 10 years, while severe RP occurred in 7.5 percent of patients at 5 years and 8.4 percent at 10 years. Nineteen percent of patients with severe RC and 67 percent of patients with severe RP required endoscopic haemostasis.
“Tissue radiosensitivity depends on tissue turnover rates,” explained the researchers. “Differences in cellular responses to radiation injury might contribute to the variation in onset times of RP and RC.”
Clinical predictors
“Adjuvant or salvage RT [hazard ratio (HR), 2.33; 95 percent confidence interval (CI), 1.34–4.08; p=0.003] was a strong predictor of RC, whereas primary RT [HR, 2.22; 95 percent CI, 1.10–4.50; p=0.027] was identified as a significant risk factor for RP,” pointed out the researchers.
Bladder volume receiving >60 Gy of >25 percent (bladder V60>25 percent) was a significant predictor of both RC (HR, 1.03; 95 percent CI, 1.01–1.04; p<0.001) and severe RC (HR, 1.04; 95 percent CI, 1.02–1.06; p<0.001).
Additionally, rectal volume receiving >70 Gy of >10 percent (rectum V70>10 percent) was a significant predictor of both RP (HR, 1.04; 95 percent CI, 1.01–1.07; p=0.007) and severe RP (HR, 1.05; 95 percent CI, 1.01–1.08; p=0.012).
Of note, antiplatelet medication was a significant risk factor for RC (HR, 2.54; 95 percent CI, 1.55–4.16; p<0.001), RP (HR, 1.54; 95 percent CI, 1.01–2.36; p=0.047), and severe RC requiring bladder irrigation and operative haemostasis (HR, 4.81; 95 percent CI, 2.15–10.7; p<0.001) and severe RP requiring hospitalization (HR, 2.65; 95 percent CI, 1.41–4.99; p=0.003).
“As life expectancy increases and incidence of cardiometabolic disease rises, more patients with prostate cancer receive antiplatelet therapy,” noted the researchers. In the study, one in four patients (26.5 percent) received antiplatelet medications at baseline.
“Comprehensive counselling regarding these potential long-term adverse effects is imperative,” highlighted the researchers. “These predictors may inform individualized risk–benefit assessment in patient decision-making and counselling, thereby optimizing patient-centred care.”