External beam radiotherapy of prostate cancer with or without high dose-rate brachytherapy: the Norwegian experience with long-term urinary and bowel adverse effects.

BACKGROUND: There are few studies utilizing the Expanded Prostate Index Composite questionnaire-26 (EPIC-26) questionnaire to examine the long-term association between Domain Summary Scores (DSSs) and Quality of Life (QoL) after External Beam Radiation Therapy (EBRT, 3DCRT [3D conventional radiotherapy]/IMRT [intensity modulated radiation therapy]) versus EBRT combined with High-Dose-Rate Brachytherapy (BT+, 3DCRT [3D conventional radiotherapy]/IMRT). In this cross-sectional study we compare long-term adverse effects and QoL after BT+ with EBRT.

METHODS: Prostate Cancer Survivors who at least 5 years previously, had undergone BT+ at Oslo University Hospital between 2004 and 2010 (n = 259) or EBRT (multicentre cohort) between 2009 and 2010 (n = 99) completed a questionnaire containing EPIC-26, Short Form-12 and questions regarding comorbidity/social status. Results were presented as DSSs and Physical/Mental Composite Scores of QoL (PCS/MCS). Regression analyses explored firstly the associations between treatment modality and DSSs and secondly the impact of DSSs on QoL. We estimated the proportions of patients with big/moderate problems. Clinical relevance was set according to the lowest limit of published Minimal Important Differences. P-values <0.05 were considered statistically significant.

RESULTS: In multivariate analysis, only the urinary incontinence DSS remained statistically (P < 0.05) and clinically significantly greater after BT+ than EBRT (90 vs. 83). The number of men with moderate/big urinary or bowel problems was halved after BT+ (P < 0.05). The number of patients with impaired PCS (score < 45) were lower in the BT+ group than the EBRT group (P = 0.02). Regression analysis showed that decreasing levels of bowel and urinary irritation/obstructive DSSs predicted worsening of PCS (P < 0.001) and MCS (P = 0.007), respectively.

CONCLUSIONS: Dose-escalated radiotherapy by BT did not negatively impact long-term adverse effects, substantial problems or QoL compared with EBRT. Future randomised studies using improved EBRT techniques are needed.