Stereotactic Body Radiation Therapy Offers a Safe, Non-invasive Treatment for Prostate Cancer Patients Over 70 Years Old

Abstract

Purpose/Objectives: Treatment of older men for prostate cancer is increasingly controversial with watchful waiting frequently being employed. However, recent publications observe a trend toward worsened biochemical recurrence-free survival with watchful waiting for prostate cancer patients over 70. Given that stereotactic body radiation therapy (SBRT) is non-invasive and delivered in only 5 days, we sought to examine the impact on patient quality of life (QOL) and outcomes in men over 70. Materials/Methods: One hundred forty-two patients with organ-confined prostate cancer (129 T1c and 13 T2a, all N0M0) received robotic radiosurgery SBRT (35 or 36.25 Gy delivered in 5 daily fractions). The mean age was 77 years (range, 71-88) and the mean PSA was 6.9 ng/ mL. Eighty patients were low-risk, 52 were intermediate risk and 10 were high risk. Androgen deprivation therapy was administered to 29 patients for up to one year. Intrarectal amifostine was administered before each fraction. Biochemical failure was assessed using the Phoenix criterion. Results: At a median follow-up of 53 months (range, 9-58 months), 10 patients died of other causes and 4 were lost to follow-up. The median PSA is 0.10 ng/mL at 48 months follow-up. Biochemical failures occurred for 3 low-risk patients (no proven local failures), 4 intermediate-risk patients (1 proven local failure), and 3 high-risk patients (1 proven local failure). The 4.5 year freedom from biochemical failure is 96%, 92%, and 70% for the lowand intermediate and high-risk groups. Acute RTOG toxicity consisted of 1.4% Grade 2 rectal, 2.1% Grade 2 urinary; no higher grade acute toxicities were observed. Late RTOG toxicity consisted of3.9% Grade 2 rectal, 10% Grade 2 urinary, and 2.3% Grade 3 urinary. Mean EPIC urinary and bowel QOL declined at 1 month post-treatment. At 12 months, mean EPIC urinary and bowel QOL returned to near baseline where they remain. Conclusions: At 4 years, SBRT yields excellent biochemical control rates with mild toxicity and minimal impact on patient quality of life for older patients. While longer follow-up is necessary to confirm these findings, these results suggest SBRT is a suitable non-invasive treatment for patients over 70. Author Disclosure: A. Katz: F. Honoraria; Accuray.