Patient-reported Quality of Life After Proton Beam Therapy for Prostate Cancer: The Effect of Prostate Size

The present study assessed the effect of prostate gland size on patient-assessed quality of life (QOL) after definitive treatment of prostate adenocarcinoma with proton beam therapy. A larger prostate size, despite receiving a greater radiation dose, did not affect QOL at 6 months, providing further support that neoadjuvant cytoreductive treatments are unnecessary. Background: In the present study, we assessed the effect of prostate gland size on patient-assessed genitourinary and gastrointestinal (GI) quality of life (QOL) after definitive treatment of prostate adenocarcinoma with proton beam therapy. Patients and Methods: As a part of a prospective outcome tracking protocol, 81 patients treated at a single center between with proton beam therapy completed the Expanded Prostate Cancer Index Composite (EPIC) questionnaire before treatment and at the follow-up examinations. We reviewed the dosimetric data, reported as V-x (volume of organ receiving x Gy), and patient-reported QOL at 6 months. Genitourinary QOL was assessed using the American Urological Association symptom score and EPIC urinary domain score. GI QOL was assessed using the EPIC GI domain score. Results: Larger prostate glands were associated with greater bladder V-70 (P < .01) and rectal V-70 (P < .01). The rectal V-70 was < 15% for all patients (range, 4%-13.8%) with the planned treatment volume coverage (percentage of the prescription dose covering 95% of the volume > 95%) maintained. Patients with larger prostates did not have a greater change in their American Urological Association symptom index scores (< 30 cm(3), +2.3; 30-49 cm(3), +3.2; >= 50 cm(3), 0.2; P = .06) or urinary domain score (< 30 cm(3), -3.6; 30-49 cm(3), -3.1; >= 50 cm(3), +3.8; P = .76) at 6 months after treatment. Also, prostate size was not associated with a change in the EPIC GI domain score at 6 months after treatment (< 30 cm(3), -3.7; 30-49 cm(3), -1.1; >= 50 cm(3), -0.55; P = .67). Conclusion: Definitive proton beam therapy for prostate cancer to a dose of 79.2 Gy resulted in excellent patient-reported urinary and GI QOL, independently of the baseline prostate size. This single-institution finding should be tested further in a multi-institutional study to confirm the potential limited role of androgen deprivation therapy. (C) 2017 Elsevier Inc. All rights reserved.