The analysis of active surveillance for Japanese young early-stage prostate cancer patients: From the PRIAS-JAPAN study.
Authors: Kato Takuma , Kimura Takahiro , Matsumoto Ryuji , Yokomizo Akira , Sato Takuma , Tohi Yoichiro , Kume Haruki , Inoue Koji , Kinoshita Hidefumi , Sakamoto Shinichi , Hara Isao , Fukuhara Hiroshi , Sugimoto Mikio ,   PRIAS-JAPAN
Published: February 2025

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Background:
The current status of active surveillance (AS) for early-stage young Japanese patients is unknown. We examined it from the data of PRIAS-JAPAN, a multicenter prospective collaborative study of AS in Japan.
Methods:
Initially, low-risk patients with a PSA density (PSAD) <0.2 and 2 or fewer positive cores were eligible. The eligibility criteria have since been revised accordingly, and from 2021, when MRI imaging was performed, the inclusion criteria allowed a PSAD of up to 0.25, no upper limit on the number of positive cores for Gleason score (GS) 3+3 cases, and up to half of the total number of positive cores for intermediate-risk GS 3+4 cases. PSA test every 3 months, rectal examination every 6 months, biopsy at 1, 4, 7, and 10 years, and every 5 years after that, and recommendation for secondary treatment after confirming pathological deterioration. The AS results and clinical outcomes were compared between the patients aged 60 years and younger (Young group: Y-group, n=165) and those over 60 years old (elderly group: E-group; n=1,109).
Results:
In the Y-group, the median age was 57 years, the median PSA at diagnosis was 4.8 ng/ml, the median prostate volume was 33.4 cm3, the median PSAD was 0.15 ng/ml/c m3,T1c was 149. At diagnosis, the Y-group had significantly smaller prostate volumes and a higher proportion of GS 3+3 cases than the E-group. The biopsy acceptance rate decreased with increasing (1
st
, 2
nd
, 3
rd,
and 4th year: 81.8%, 70.3%, 34.4%, and 13.3%). The reclassification rate increased over time (1
st
, 2
nd
, 3
rd
and 4th year: 28.7%, 30.8%, 27.3%, and 50.0%). The persistence rate of the Y-group decreased over time, with a 10-year persistence rate of 19.2%, with no significant difference between the two groups. The 10-year metastasis-free survival (MFS), 10-year overall survival (VS), and 10-year cancer-specific survival (CSS) rates of the Y-group were 98.8%, 98.9%, and 100%, respectively. Although OS was lower in the Y-group (p=0.051, HR=2.29. 95%CI 1.004-5.21), MFS and CSS did not significantly differ between the two groups. The Y-group was more likely than the E-group to choose prostatectomy (38.3%) as the next treatment, while they did not want hormone therapy (4,7%) or watchful waiting (6.5%).
Conclusions:
Although the Y-group was superior to the E-group in OS, there was no significant difference in MFS and CSS between the two groups.

AS persistence rate
Metastasis-free survival

3 year
5 year
10 year
13 year

3 year
5 year
10 year
13 year

≤60y.o
55.7%
39.9%
19.2%
17.1%
≤60y.o
100%
100%
99%
99%

60y.o<
58.2%
38.5%
16.3%
12.0%
60y.o<
100%
100%
99%
98%

Overall survival
Cancer-specific survival

3 year
5 year
10 year
13 year

3 year
5 year
10 year
13 year

≤60y.o
100.0%
100.0%
98.9%
95.3%
≤60y.o
100.0%
100.0%
100.0%
100.0%

60y.o<
97.9%
97.0%
92.2%
88.7%
60y.o<
99.9%
99.9%
99.9%
99.9%