Early toxicity and patient reported quality-of-life in patients receiving proton therapy for localized prostate cancer: a single institutional review of prospectively recorded outcomes

Abstract

Background: We report prospectively captured clinical toxicity and patient reported outcomes in a single institutional cohort of patients treated for prostate cancer with proton beam therapy (PBT). This is the largest reported series of patients treated mostly with pencil beam scanning PBT.

Methods: We reviewed 231 patients treated on an IRB approved institutional registry from 2013 to 2016; final analysis included 192 patients with > 1-year of follow-up. Toxicity incidence was prospectively captured and scored using CTCAE v4.0. International Prostate Symptoms Score (IPSS), Sexual Health Inventory for Men (SHIM) score, and Expanded Prostate Cancer Index Composite (EPIC) bowel domain questionnaires were collected at each visit. Univariate Cox regression was used to explore associations of grade 2+ toxicity with clinical, treatment, and dosimetric variables.

Results: Median follow-up was 1.7 years. Grade 3 toxicity was seen in 5/192 patients. No grade 4 or 5 toxicity was seen. Patient reported quality-of-life showed no change in urinary function post-radiation by IPSS scores. Median SHIM scores declined by 3.7 points at 1-year post-treatment without further decrease beyond year 1. On univariate analysis, only younger age (HR = 0.61, p = 0.022) was associated with decreased sexual toxicity. EPIC bowel domain scores declined from 96 at baseline (median) by an average of 5.4 points at 1-year post-treatment (95% CI: 2.5-8.2 points, p < 0.001), with no further decrease over time. Bowel toxicity was mostly in the form of transient rectal bleeding and was associated with anticoagulation use (HR = 3.45, p = 0.002).

Conclusions: Grade 3 or higher toxicity was rare at 2-years after treatment with PBT for localized prostate cancer. Longer follow-up is needed to further characterize late toxicity and biochemical control.

Trial registration: NCT, NCT01255748 . Registered 1 January 2013.

Keywords: Patient reported outcomes; Prostate cancer; Proton therapy; Quality of life.

Fig. 1

Patient-reported quality-of-life measures. Box-whisker representation of QOL scores at pre-treatment, 1-year, 1.5-year, and 2-years post-treatment (a)=IPSS score, (b)=IPSS bother score, (c)=Nocturia score, (d)=EPIC bowel domain score, and (e)=SHIM score

Fig. 2

Cumulative actuarial rates for late grade 2+ toxicity (> 90 days post-treatment). Grade 3 toxicity was seen in 5/192 patients, there were no grade 4/5 toxicity. Grade 2 bowel toxicity was mostly transient rectal bleeding managed by enemas/suppositories or laser coagulation. Grade 2 GU toxicity mostly consisted of urinary symptoms managed by α1 adrenoceptor blockers. Grade 2 erectile dysfunction was defined as requiring medications for erectile function. Grade 2 hip pain was pain requiring anti-inflammatory medications