Baseline patient characteristics are shown in Table 2. Median follow-up was 34 months (maximum: 54 months). Between May 2016 and Dec 2020, 439 patients answered the FACT-QoL questionnaire at some point. These 439 patients were all that had been treated with SBRT for prostate cancer with a curative intent in our institution during this period. The median age was 73 years, the median PSA before all treatments was 9.2 ng/mL, clinical T2a was the highest at 47%, and Gleason Score Group by NCCN was 28% and 27% for Group 2 and 3, respectively. The NCCN medium risk was 53% and high risk was also included at 42%. Short-term hormone combination for 4–6 months was 42% and long-term hormone combination was 36%. 177 patients (40%) had hydrogel spacer inserted between the prostate and rectum before SBRT.
The cumulative total number of patients who were caught in exclusion criteria during the same period was: SBRT for (1) lymph node metastasis in 12 patients; (2) bone metastasis in 11 patients; (3) castration-resistant prostate cancer in seven patients; (5) after radical prostatectomy in one patient; (6) local recurrence after external beam radiation therapy in two patients; (7) local recurrence after high-intensity focused ultrasound (HIFU) in three patients; (8) not 5 fractionations in one patient.
314 patients (71%) before SBRT, 242 patients (55%) at 1 month, 46 patients at 2 month, and 246 patients at 3 to 4 month, 197 patients at 5–7 month, 190 patients at 8–10 month, 165 patients at 11–13 month, 137 patients at 14–16 month, 117 patients at 17–19 month, 102 patients at 20–22 month, 85 patients at 23–25 month, 61 patients at 29–31 month, 50 patients at 32–34 month, 54 patients at 35–37 month, 44 patients at 38–42 month, 38 patients at 43–54 month, 29 patients at 43–48 month, 9 patients at 49–54 month filled out the questionnaire. Since we included all patients received SBRT in this survey, approximate 30% of patients did not complete the questionnaire before treatment.
In all of FACT P-TOI, FACT G Total, and FACT P-total, the QoL score at 1 month after the end of SBRT was once significantly lower than the value before SBRT (Fig. 1). The average score for each QoL dropped from 78.84 (standard error: 0.77) before SBRT to 72.35 (1.02) at 1 month in FACT P-TOI (p < 0.0001 by t-test), from 79.91 (0.79) to 75.38 (0.96) in FACT G Total (p = 0.0003), and from 114.22 (1.05) to 105.78 (1.31) in FACT P-total (p < 0.0001), respectively. After that, an improvement trend was seen in the second month (the average score: 74.62 (SE: 2.57), 77.13 (2.09), and 107.88 (3.23), respectively). Furthermore, at 3–4 month, all of FACT P-TOI (p = 0.0011, the average score: 76.80 (SE: 0.88)), FACT G Total (p = 0.0410, 78.15 (0.94)), and FACT P-total (p = 0.0029, 111.19 (1.24)) improved significantly from the 1st month. In the subsequent course, there was basically no re-decrease in the plateau until the 49-54th months.
In the long-term hormone-administered group, the QOL reduction of FACT P-TOI (67.99) and FACT P-total (102.08) at 1 month was larger than that in the short-term administration group (administration period of 6 months or less) and the hormone-free group (Fig. 2). In the hormone-free group, the bottom of all QoL was 2 months instead of 1 month. With respect to use of hydrogel spacer, the score of FACT P-TOI, FACT G Total, and FACT P-total at 1 month was 71.35 (SE: 1.02), 74.41 (0.96), and 104.26 (1.31) without spacer versus 74.97 (1.76) (p = 0.11 by unpaired t-test), 77.94 (1.69) (p = 0.10), and 109.74 (2.28) (p = 0.062) with spacer, respectively. With respect to the SBRT dose, the score of FACT P-TOI, FACT G Total, and FACT P-total at 1 month was 72.58 (SE: 1.17), 75.22 (1.09), and 105.60 (1.46) after 36.25 Gy (p = 0.33 of 36.25 Gy versus 40 Gy, p = 0.68 of 36.25 Gy versus 42.5 Gy, and p = 0.99 of 40 Gy versus 42.5 Gy), and 71.77 (2.21), 76.05 (2.16), and 106.39 (3.02) (p = 0.71, 0.82, and 0.74) after 40 Gy, 71.85 (6.29), 74.15 (5.47), and 105.15 (7.88) (p = 0.79, 0.84, and 0.88) after 42.5 Gy, respectively.
P7 (I have difficulty urinating) (the average score: 3.25 before SBRT, 2.49 at 1 month, and 3.14 at 2 months) and BL2 (I urinate more frequently than usual) (2.58, 1.62, and 2.22) bottomed out one month after the end of SBRT (both p < 0.0001) (Fig. 3). Improvement was seen at 2 month and was fully recovered at 3–4 month. P6 (I have trouble moving my bowels) and P8 (My problems with urinating limit my activities) on restriction of activity by urine continued to decline until the second month and recovered at 3–4 month (Fig. 3).
The percentage of those who answered that they were suffering from side effects of GP5 (I am bothered by side effects of treatment) was also the highest at 22% in the first month after the end of SBRT from 8% at pre-SBRT, and dropped to 11% in the 3rd to 4th months (Fig. 4). After that, it gradually decreased over time. Including "somewhat", it changed from 15% before SBRT into 45% at 1st month, 32% at 2nd month, and 28% at 3–4 months.