Patient-reported outcomes following stereotactic body radiation therapy for clinically localized prostate cancer

Abstract

Background: Stereotactic body radiation therapy (SBRT) delivers high doses of radiation to the prostate while minimizing radiation to adjacent normal tissues. Large fraction sizes may increase the risk of functional decrements. Treatment-related bother may be more important to a patient than treatment-related dysfunction. This study reports on patient-reported outcomes following SBRT for clinically localized prostate cancer.

Methods: Between August 2007 and July 2011, 228 consecutive hormone-naïve patients with clinically localized prostate cancer were treated with 35-36.25 Gy SBRT delivered using the CyberKnife Radiosurgical System (Accuray) in 5 fractions. Quality of life was assessed using the American Urological Association Symptom Score (AUA) and the Expanded Prostate Cancer Index Composite (EPIC)-26. Urinary symptom flare was defined as an AUA score 15 or more with an increase of 5 or more points above baseline 6 months after treatment.

Results: 228 patients (88 low-, 126 intermediate- and 14 high-risk) at a median age of 69 (44-90) years received SBRT with a minimum follow-up of 24 months. EPIC urinary and bowel summary scores declined transiently at 1 month and experienced a second, more protracted decline between 9 months and 18 months before returning to near baseline 2 years post-SBRT. 14.5% of patients experienced late urinary symptom flare following treatment. Patients who experienced urinary symptom flare had poorer bowel quality of life following SBRT. EPIC scores for urinary bother declined transiently, first at 1 month and again at 12 months, before approaching pre-treatment scores by 2 years. Bowel bother showed a similar pattern, but the second decline was smaller and lasted 9 months to 18 months. EPIC sexual summary and bother scores progressively declined over the 2 years following SBRT without recovery.

Conclusions: In the first 2 years, the impact of SBRT on urination and defecation was minimal. Transient late increases in urinary and bowel dysfunction and bother were observed. However, urinary and bowel function and bother recovered to near baseline by 2 years post-SBRT. Sexual dysfunction and bother steadily increased following treatment without recovery. SBRT for clinically localized prostate cancer was well tolerated with treatment-related dysfunction and bother comparable to conventionally fractionated radiation therapy or brachytherapy.

Figure 1

Urinary function. (a) EPIC urinary summary domain scores at baseline and following SBRT for prostate cancer. Thresholds for clinically significant changes in scores (½ standard deviation above and below the baseline) are marked with dashed lines. EPIC scores range from 0–100 with higher values representing a more favorable health-related QOL. (b) Percentage of patients with urinary symptom flare at each follow-up.

Figure 2

Bowel function. (a) EPIC bowel summary domain scores at baseline and following SBRT for prostate cancer. (b) EPIC bowel summary domain scores in patients with or without urinary symptom flare. Thresholds for clinically significant changes in scores (½ standard deviation above and below the baseline) are marked with dashed lines. EPIC scores range from 0–100 with higher values representing a more favorable health-related QOL.

Figure 3

Sexual function. EPIC sexual summary domain scores at baseline and following SBRT for prostate cancer. Thresholds for clinically significant changes in scores (½ standard deviation above and below the baseline) are marked with dashed lines. EPIC scores range from 0–100 with higher values representing a more favorable health-related QOL.

Figure 4

EPIC urinary bother at baseline and following SBRT for prostate cancer. (a) Urinary bother was stratified to three levels of bother: no problem, very small-small problem, and moderate-big problem. (b) Average overall urinary bother scores (Question 5 of the EPIC-26). Thresholds for clinically significant changes in scores (½ standard deviation above and below the baseline) are marked with dashed lines. EPIC scores range from 0–100 with higher values representing a more favorable health-related QOL.

Figure 5

EPIC bowel bother at baseline and following SBRT for prostate cancer. (a) Bowel bother was stratified to three levels of bother: no problem, very small-small problem, and moderate-big problem. (b) Average overall bowel bother scores (Question 7 of the EPIC 26). (c) EPIC bowel bother scores in patients with or without urinary symptom flare. Thresholds for clinically significant changes in scores (½ standard deviation above and below the baseline) are marked with dashed lines. EPIC scores range from 0–100 with higher values representing a more favorable health-related QOL.

Figure 6

EPIC sexual bother at baseline and following SBRT for prostate cancer. (a) Sexual bother was stratified to three levels of bother: no problem, very small-small problem, and moderate-big problem. (b) Average overall sexual bother scores (Question 12 of the EPIC 26). Thresholds for clinically significant changes in scores (½ standard deviation above and below the baseline) are marked with dashed lines. EPIC scores range from 0–100 with higher values representing a more favorable health-related QOL.