Clinical characteristics and management of late symptom flare following stereotactic body radiation therapy for clinically localized prostate cancer.

Abstract

194 Background: Stereotactic body radiation therapy (SBRT) is increasingly utilized as primary treatment for clinically localized prostate cancer. While acute urinary symptoms are well recognized, late toxicities of SBRT have not been fully described. Here, we characterize the clinical features of late symptom flare and describe symptom management approaches. Methods: Two hudred sixteen patients with clinically localized prostate cancer were treated with SBRT between February 2008 and January 2011 at Georgetown University Hospital. Twenty-nine patients who experienced late-symptom flare were included in this retrospective analysis. Treatment was delivered using the CyberKnife (35 Gy to 36.25 Gy in five fractions). Prevalence of urinary toxicities was determined using CTCAE v.4. Patient-reported urinary symptoms were assessed using the American Urological Association Symptom Score (AUA) and the Expanded Prostate Cancer Index Composite (EPIC) short form. Results: Median age was 66 with 55% being of African descent. Late grade 2 frequency/urgency peaked at 12 months (17.2%), then returned to baseline at 18 months. Late grade 2 retention peaked at 18 months (65.5%), then returned to baseline at 24 months. Late grade greater than or equal to 1 dysuria peaked at nine months (25.0%), then returned to baseline at 24 months. Alpha-antagonist usage peaked at 18 months (85%) then decreased at 24 months. At 12 months, 21% required anti-inflammatories and/or urethral analgesics. Median AUA score rose from a baseline of 6 to 15 at 12 months, then returned to baseline by 24 months. EPIC urinary function and bother scores dropped to a nadir at 9 to 12 months post-treatment, then returned to baseline at 24 months. Conclusions: Symptom flare is a late syndrome consisting of various degrees of urinary frequency/urgency, retention and dysuria. It occurs approximately one year following SBRT, resolves spontaneously, and urinary function returns to baseline by two years. Early identification and initiation of conservative symptomatic management may decrease the need for invasive interventions. Anticipatory counseling prior to treatment may limit bother due to these transient urinary symptoms.