Late, persistent, substantial treatment-related symptoms (LAPERS) following low-dose-rate brachytherapy for prostate...

We aim to report 1) prevalence, 2) incidence, and 3) late, persistent, substantial treatment-related symptoms (LAPERS) after low-dose-rate brachytherapy (LDRBT) for prostate cancer.

The study comprised men treated with LDRBT in a single Australian institution between 2014 and 2019. All men completed the Expanded Prostate Cancer Index Composite 26 (EPIC-26) questionnaire pretreatment, and at regular intervals posttreatment. 'Substantial' symptoms were defined as 'moderate' or 'big' problems in EPIC-26 which assesses the degree of symptom bother for each functional domain. 'Persistent' symptoms were defined as 'substantial' symptoms that present in at least half of the 'late' followup assessments. This provided a binary LAPERS outcome (yes/no). Prevalence (at each time point) and cumulative incidence of substantial symptoms were also reported.

A total of 172 men with 'baseline' and at least three 'late' followup EPIC-26 were included in the study. The median followup was 60 months (IQR: 36-74 months). For overall urinary function, prevalence of substantial symptoms was highest at 10% 6-month posttreatment, with 5-year cumulative incidence of 18%, but only 2% had LAPERS. For overall bowel function, prevalence of substantial symptoms was highest at 7% 12-months posttreatment, with 5-year cumulative incidence of 15%, and only 2% had LAPERS. For sexual function, prevalence of substantial symptoms was highest at 28% 6-months posttreatment, with 5-year cumulative incidence of 49%, and 22% had LAPERS (baseline-adjusted LAPERS 17%).

There were considerable differences in late toxicities using different toxicity-reporting approaches. LAPERS approach is more reflective of 'true' late toxicities considering duration and persistence of symptoms.