Nearly 50,000 veterans are diagnosed with cancer within the Veterans Health Administration annually with prostate cancer (PC) being the most frequently diagnosed, accounting for 29% of all cancers diagnosed.1 The treatment of PC depends on the stage and risk group at presentation and patient preference. Men with early stage, localized PC can be managed with prostatectomy, radiation therapy, or active surveillance.2
Within the Veterans Health Administration, more patients are treated with radiation therapy than with radical prostatectomy.3 This is in contrast to the civil health system, where more patients are treated with radical prostatectomy than with radiation therapy.4,5 Radiation therapy for PC can be given externally with external beam radiation therapy or internally with brachytherapy (BT). BT is categorized by the rate at which the radiation dose is delivered and generally grouped as low-dose rate (LDR) or high-dose rate (HDR). LDRBT consists of permanently implanting radioactive seeds, which slowly deliver a radiation dose over an extended period. HDRBT consists of implanting catheters that allow delivery of a radioactive source to be placed temporarily in the prostate and removed after treatment. The utilization of HDRBT has become more common as treatment has evolved to consist of fewer, larger fractions in a shorter time, making it a convenient treatment option for men with PC.6 The veteran population has singular medical challenges. These patients differ from the general population and are often underrepresented in medical research and published studies.7 There are no studies exploring the treatment-associated toxicities from HDRBT treatment for PC specifically in the veteran population. The objective of this study is to report our findings regarding the veteran-reported and physician-graded toxicities associated with HDRBT as monotherapy in veterans treated through the US Department of Veterans Affairs (VA) for PC.
Methods
We performed a retrospective cohort study of a prospectively maintained, institutional review board-approved database of patients treated with HDRBT for PC. Veterans were seen in consultation at Edward Hines, Jr. VA Hospital (EHJVAH) in Hines, Illinois. This is the only VA hospital in Illinois that offers radiation therapy, so it acted as a tertiary center, receiving referrals from other, neighboring VA hospitals. If the veteran was deemed a good BT candidate and elected to proceed with HDRBT, HDR treatment was performed at a partnering academic institution equipped to provide HDRBT (Loyola University Medical Center).
We selected patients with National Cancer Center Network (NCCN) low- or intermediate-risk PC undergoing definitive HDRBT as monotherapy using 13.5 Gy x 2 fractions delivered over 2 implants that were 1 to 2 weeks apart. Patients who received androgen deprivation therapy (ADT) were excluded from this study. No patients received supplemental external beam radiation. Men with unfavorable intermediate risk PC were offered ADT and BT in accordance with NCCN guidelines. However, patients with unfavorable intermediate-risk PC who declined ADT or who were deemed poor ADT candidates due to comorbidities were treated with HDR as monotherapy and included in this study.8
HDR Treatment
Our HDRBT implant procedure and treatment planning details have been previously described.9 In brief, patients were implanted with between 17 and 22 catheters based on gland size under transrectal ultrasound guidance. After implantation, computed tomography and, when possible, magnetic resonance imaging of the prostate were obtained and registered for target delineation. The prostate was segmented, and an asymmetric planning target volume of 0 to 5 mm was created and extended to encompass the proximal seminal vesicles. The second fraction was given 1 to 2 weeks after initial treatment, based on patient, physician, and operating room availability.
Health-Related Quality of Life Assessment
Veteran-reported genitourinary (GU), gastrointestinal (GI), and sexual health-related quality of life (hrQOL) were assessed using the validated International Prostate Symptom Score (IPSS) and the Expanded Prostate Cancer Index Composite Short Form (EPIC-26) instruments.10,11 Baseline veteran-reported hrQOL scores in the GU, GI, and sexual domains were obtained prior to each veteran’s first HDR treatment. Veteran-reported hrQOL scores were assessed at each of the patient’s follow-up appointments. Physician-graded toxicity was assessed Common Terminology Criteria for Adverse Events (CTCAE) v 4.03 criteria.12 Physician-graded toxicity was assessed at each follow-up visit and reported as the highest grade reported during any follow-up examination.
Follow-up appointments typically occurred at 1 month, 3 months, 6 months, 12 months, and subsequently every 6 months after the second HDR treatment. Follow-up appointments were conducted in the radiation oncology department at EHJVAH.
Minimal Clinically Important Differences
To evaluate the veteran-reported hrQOL, we characterized statistically significant differences in IPSS or EPIC-26 scores over time as compared with baseline values as clinically important or not clinically important through the use of reported minimal clinically important difference (MCID) assessments.13-15 For the IPSS, we used reported data that showed a change of ≥ 3.0 points represented a clinically meaningful change in urinary function.14 For the EPIC-26 scores, we used reported data that showed a change of ≥ 6 points for urinary incontinence score, ≥ 5 points for urinary obstruction score, ≥ 4 points for bowel score, and ≥ 10 points for sexual score to represent an MCID.15
