Statistical Analysis
Changes in veteran-reported hrQOL over time were compared using mixed linear effects models, with the time since the last BT implant serving as the fixed variable. Effects were deemed statistically significant if P < .05. If a statistically significant difference from baseline was found at any time point, additional evaluation was done to see if the numerical difference in the assessment led to an MCID as described above. IBM SPSS Statistics for Windows, version 25.0 was used for data analysis.
Results
Seventy-four veterans were included in the study. The median follow-up was 18 months (range 1-43). The demographic and oncologic specifics of the treated veterans are outlined in Table 1.
There was a significant increase in IPSS (P < .001) with reciprocal decline in EPIC-26 urinary incontinence (P = .008) and EPIC-26 urinary obstruction scores (P = .001) from baseline over time (Table 2 and Figure 1). At the 18-month follow-up assessment, there was no longer a significant difference in the EPIC-26 urinary obstruction score from baseline (88.7 vs 84.0, P = .31). The increases in IPSS at the 1-, 3-, and 6-month assessments met the criteria for MCID. The decrease in EPIC-26 urinary incontinence scores at the 1-, 3-, 6-, 12-, and 18-month assessments were found to be an MCID, as were the decrease in EPIC-26 urinary obstruction scores at the 1-, 3-, 6-, and 12-month assessments.
There was a significant decline in EPIC-26 bowel scores from baseline over time (P = .03). The decline in the EPIC-26 bowel hrQOL scores at the 1-, 3-, and 6-month follow-up assessment were significantly different from the baseline value. However, only the decrease seen at the 1-month assessment met criteria for MCID.
There was a significant decline in EPIC-26 sexual scores from baseline over time (P < .001). The decline in EPIC-26 sexual score noted at each follow-up compared with baseline was statistically significant. Each of these declines met criteria for an MCID.
The rate of grade 2 GU, GI, and sexual physician-graded toxicity was 65%, 5%, and 53%, respectively (Figure 2). There was a single incident of grade 3 GU toxicity, which was a urethral stricture. There were no reported grade 3 GI or sexual toxicities, nor were there grade 4 or 5 toxicities. There were 5 total incidents of acute urinary retention for a 6.8% rate overall.
Discussion
We performed a retrospective study of veterans with low- or intermediate-risk PC undergoing definitive HDR prostate BT as monotherapy. We found that veterans experienced immediate declines in GU, GI, and sexual hrQOL after treatment. However, each trended toward a return to baseline over time, with the EPIC-26 urinary obstruction and the EPIC-26 bowel scores showing no difference from the baseline value within 18 months and 12 months, respectively. The physician-reported toxicities were low, with only 1 incidence of grade 3 GU toxicity, no grade 3 GI or sexual toxicities, and no grade 4 or 5 toxicity. This suggests that HDRBT is a well-tolerated and safe, definitive treatment for veterans with localized PC.
In a series similar to ours, Gaudet and colleagues reported on their single institutional results of treating 30 low- or intermediate-risk PC patients with HDRBT as monotherapy.16 Patients included in their study were civilians from the general population, treated in a similar fashion to the veterans treated in our study. Each patient received 27 Gy in 2 fractions given over 2 implants. The authors collected patient-reported hrQOL results using the IPSS and EPIC questionnaires and found that 57% of patients treated experienced moderate-to-severe urinary symptoms at the 1-month assessment after implantation, with a rapid recovery toward baseline over time. In contrast, GI symptoms did not change from baseline, while sexual symptoms worsened after implantation and failed to return to baseline.
