In this prospective study, we evaluated the QoL of 439 patients treated with SBRT for low-, intermediate-, and high-risk PC. To date, most QoL evaluations using FACT-P after SBRT for PC have only done so for metastatic cases (6–8). However, since these studies did not irradiate the primary prostate lesion, their results cannot be compared with the QoL after radical SBRT. Using the FACT-P questionnaire, it is highly novel to see the time-series changes in QoL after radical PC SBRT. The FACT-P has also been used in many phase III studies on PC (9–18). In this report, QoL declined at 1 month after the last SBRT, then recovered, and returned to the same level as before treatment by 3–4 months. The decrease in QoL in the first month was particularly remarkable in patients who received combined long-term hormone injections. One month after the last SBRT, about 22% of people were "quite a bit or very much" bothered by the side effects experienced. Since the QoL score of patient-reported side effects (i.e., P6, P7, P8, and BL2) also declined at the same time, this QoL change would be due to SBRT-induced acute toxicity, although we did not compare patient-reported outcome measures (PROMS) with toxicity assessment. In this study, we could not report data on the correlation between physician- and patient-reported outcomes.
According to the previous reports (19–26), physician-reported acute GI and GU toxicity of grade 3–5 after SBRT of 2, 4, or 5 fractions were 0–2% and 0-2.5%, respectively. In our study, 45% of patients answered “somewhat” or more to GP5 (I am bothered by side effects of treatment) at 1 month after the last SBRT. Moreover, 22% of patients responded that they were “quite a bit” or more troubled by the treatment’s side effects. In general, patient-reported side effects are more frequent than physician-reported side effects.
According to the previous reports (19–26), physician-reported chronic GI and GU toxicity of grade 3–5 after SBRT were 0–7% and 0-5.5%, respectively. Periprostatic hydrogel placement followed by prostate SBRT may result in minimal GI toxicity. In our study, 10–30% and 0–13% of patients answered “somewhat” or more and “quite a bit” or more in GP5 after 3–4 months, respectively, although these figures could not be compared directly since there was a difference of physician- and patient-reported outcome.
There were times when the response rate was small, such as after the 38th month. Since we included all patients treated with SBRT during this period, only 71% of patients had a baseline assessment and 55% were evaluated at 1 month. Thus, our QoL assessments may follow a heterogeneous distribution.
Previous studies have investigated the QoL change after conventional intensity-modulated radiation therapy (IMRT), but unlike our study, included an initial questionnaire 3 months after irradiation and found no decrease in QoL (27–29). In contrast, we collected novel QoL data before SBRT, as well as during the first and second months after SBRT. Moreover, we compared our findings with previous QoL data of patients treated using low dose rate (LDR) and high dose rate (HDR) brachytherapy. According to Slevin et al. (30), maximal deterioration in mean urinary (p < 0.001) and sexual summary scores using a validated Expanded Prostate Cancer Index Composite (EPIC) questionnaire was noted 6 weeks after implantation, with severe urinary symptoms and moderate bowel/sexual symptoms after HDR brachytherapy. At 6 months, urinary and bowel QoL improved to involve only mild impairment, which was fully resolved at 10 months (30). According to Strom et al. (31), after a median follow-up of 32 months, HDR brachytherapy (27–28 Gy in two fractions) and IMRT (74–81 Gy in 37–45 fractions) patients had significantly less deterioration in their urinary health related quality of life (HRQoL) than LDR (145 Gy in one fraction) brachytherapy patients at 1 and 3 months after irradiation. The only significant decrease in bowel HRQoL between the groups was observed 18 months after treatment, at which point IMRT patients had a slight, but significant, deterioration in their bowel HRQoL compared with HDR and LDR brachytherapy patients (31). As with brachytherapy, a heterogenous dose was prescribed to spare the urethra. The homogeneous dose distribution may affect patients in a different way than a heterogeneous brachytherapy treatment plan.
In a single-arm, phase II trial from multiple centers in Singapore (32), QoL of 74 men was assessed by EPIC at pretreatment, 12, and 24 months after SBRT of 36.25 Gy in 5 fractions. Overall, no significant change was observed in QoL scores over time across the three domains of urinary, bowel, and sexual scores (32). The Dutch HYPO-RT-PC trial with the updated long-term QoL analyses at baseline, the end of radiotherapy, months 3, 6, 12, and 24 after radiotherapy, every other year thereafter up to 10 years, and at 15 years using the validated Prostate Cancer Symptom Scale (PCSS) and European Organization for Research and Treatment of Cancer Quality-of-Life Questionnaire (EORTC QLQ-C30) confirmed that ultra-hypofractionated radiotherapy of 42.7 Gy in 7 fractions (n = 583) was equally well tolerated as conventionally fractionated RT of 78 Gy in 39 fractions (n = 582) up to 6 years after treatment (33). These results were also consistent with the data after one year in the present study.
According to Georgetown University’s report (6), which is the only existing study looking at QoL one month after SBRT of 35 Gy or 36.25 Gy in 5 fractions, the median baseline American Urological Association symptom score of 8 in 96 men significantly increased to 11 at 1 month (p = 0.001), but returned to baseline at 3 months (p = 0.60). Although a sole questionnaire after one month might have been really too short, it was conducted even in this survey by according to Georgetown University’s report (6). In a meta-analysis of curative-intent SBRT for localized PC (34), the EPIC-26 was used to assess 3,293 patients. Information for urinary, bowel, and sexual domain scales was readily extractable, and the data were pooled. The EPIC urinary and bowel scores returned to baseline by 2 years post-treatment (p = 0.90 and 0.09, respectively) and did not significantly differ at 5 years post-SBRT (p = 0.50 and 0.80, respectively), although these studies did not include early 1 or 2 month QoL measures. These results do not differ substantially from those of our study.