Five-year outcomes from a prospective trial of image-guided accelerated hypofractionated proton therapy for prostate cancer

<p><b>Purpose:</b> To report 5-year outcomes of a prospective trial of image-guided accelerated hypofractionated proton therapy (AHPT) for prostate cancer.</p> <p><b>Patients and methods:</b> 215 prostate cancer patients accrued to a prospective institutional review board-approved trial of 70Gy(RBE) in 28 fractions for low-risk disease (<i>n</i> = 120) and 72.5Gy(RBE) in 29 fractions for intermediate-risk disease (<i>n</i> = 95). This trial excluded patients with prostate volumes of ≥60 cm³ or International Prostate Symptom Scores (IPSS) of ≥15, patients on anticoagulants or alpha-blockers, and patients in whom dose-constraint goals for organs at risk (OAR) could not be met. Toxicities were graded prospectively according to Common Terminology Criteria for Adverse Events (CTCAE), version 3.0. This trial can be found on ClinicalTrials.gov (NCT00693238).</p> <p><b>Results:</b> Median follow-up was 5.2 years. Five-year rates of freedom from biochemical and clinical disease progression were 95.9%, 98.3%, and 92.7% in the overall group and the low- and intermediate-risk subsets, respectively. Actuarial 5-year rates of late radiation-related CTCAE v3.0 grade 3 or higher gastrointestinal and urologic toxicities were 0.5% and 1.7%, respectively. Median IPSS before treatment and at 4+ years after treatment were 6 and 5 for low-risk patients and 4 and 6 for intermediate-risk patients.</p> <p><b>Conclusions:</b> Image-guided AHPT 5-year outcomes show high efficacy and minimal physician-assessed toxicity in selected patients. These results are comparable to the 5-year results of our prospective trials of standard fractionated proton therapy for patients with low-risk and intermediate-risk prostate cancer. Longer follow-up and a larger cohort are necessary to confirm these findings.</p

Sperm preservation and neutron contamination following proton therapy for prostate cancer study

<p><b>Background:</b> The present study investigates the impact of scatter dose radiation to the testis on ejaculate and sperm counts from treatment of prostate cancer with passive-scatter proton therapy.</p> <p><b>Material and methods:</b> From March 2010 to November 2014, 20 men with low- or intermediate-risk prostate cancer enrolled in an IRB-approved protocol and provided a semen sample prior to passive-scatter proton therapy and 6–12 months following treatment. Men were excluded if they had high-risk prostate cancer, received androgen deprivation therapy, were on alpha blockers (due to retrograde ejaculation) prior to treatment, had baseline sperm count <1 million, or were unable to produce a pre-treatment sample or could not provide a follow-up specimen. Sperm counts of 0 were considered azoospermia and <15 million/ml were classified as oligospermia.</p> <p><b>Results:</b> Four patients were unable to provide a sufficient quantity of semen for analysis. Among the 16 remaining patients, only one was found to have oligospermia (7 million/ml). There was a statistically significant reduction in semen volume (median, 0.5 ml) and increase in pH (median 0.5). Although not statistically significant, there appeared to be a decline in sperm concentration (median, 16 million/ml), total sperm count (median, 98.5 million), normal morphology (median, 9%), and rapid progressive motility (median, 9.5%).</p> <p><b>Discussion:</b> Men did not have azoospermia 6–12 months following passive-scatter proton therapy indicating minimal scatter radiation to the testis during treatment. Changes in semen quantity and consistency may occur due to prostate irradiation, which could impact future fertility and/or sexual activity.</p