Prostate-specific antigen bounce after 125I-brachytherapy for prostate cancer is a favorable prognosticator in patients who are biochemical recurrence-free at 4 years and correlates with testosterone

Prostate-specific antigen (PSA) nadir and experience of PSA bounce after low-dose-rate brachytherapy for prostate cancer predicts clinical failure

OBJECTIVE

This study aimed to assess if prostate-specific antigen (PSA) threshold and PSA bounce are associated with oncological control after low-dose-rate brachytherapy (LDR-BT) alone or with external beam radiotherapy (EBRT), with or without androgen deprivation therapy (ADT), considering serum testosterone levels.

METHODS

This study enrolled 944 prostate cancer patients treated at a single institution with LDR-BT alone or LDR-BT combined with EBRT, with or without ADT. The Fine-Gray hazard model was used to evaluate factors related to clinical failure, including experience of PSA bounce between baseline and 2, 4, or 7 years after LDR-BT and PSA value (0.1, 0.2, or 0.5 ng/mL) with normal testosterone levels at 2, 4, and 7 years after LDR-BT, respectively.

RESULTS

Patients with normal testosterone levels and a PSA of 0.2 or 0.5 ng/mL at 2, 4, and 7 years after LDR-BT had a significantly better clinical failure free rate (CFFR) than those with PSA levels >0.2 or >0.5 ng/mL or low testosterone levels. Multivariate analysis revealed that PSA <0.1, 0.2, or 0.5 ng/mL with normal testosterone levels at 2, 4, and 7 years and experience of PSA bounce between baseline and 2 or 4 years after LDR-BT were significantly related to better CFFR.

CONCLUSIONS

Patients with normal serum testosterone levels who reached PSA of <0.1, 0.2, or 0.5 ng/mL after LDR-BT, or those who experienced PSA bounce, showed better oncological control.

Prostate-Specific Antigen Bounce after 125I Brachytherapy Using Stranded Seeds with Intraoperative Optimization for Prostate Cancer

Prostate-specific antigen (PSA) bounce is common in patients undergoing 125I brachytherapy (BT), and our study investigated its clinical features. A total of 100 patients who underwent BT were analyzed. PSA bounce and large bounce were defined as an increase of ≥0.2 and ≥2.0 ng/mL above the initial PSA nadir, respectively, with a subsequent decline without treatment. Biochemical failure was defined using the Phoenix definition (nadir +2 ng/mL), except for a large bounce. With a median follow-up of 49 months, 45% and 7% of the patients experienced bounce and large bounce, respectively. The median time to bounce was 24 months, and the median PSA value at the bounce spike was 1.62 ng/mL, a median raise of 0.44 ng/mL compared to the pre-bounce nadir. The median time to bounce recovery was 4 months. The post-bounce nadir was obtained at a median of 36 months after low-dose-rate BT. On univariate analysis, age, the PSA nadir value at 2 years, and prostate volume were significant factors for PSA bounce. The PSA nadir value at 2 years remained significant in multivariate analysis. We should carefully monitor young patients with high prostate volume having a >0.5 PSA nadir value at 2 years for PSA bounce.

Animal study of a newly designed metal airway brachytherapy stent loaded with radioactive 125I seeds

AIM

To evaluate dynamic tissue changes after airway stenting (AS) with a newly designed metal brachytherapy stent (BS) loaded with radioactive ¹²⁵I seeds in normal rabbits.

METHODS

Forty-five normal New Zealand white rabbits were divided into 3 groups (group A: stent without seeds; group B: stent with 0.4 mCi active seeds; group C: stent with 0.8 mCi active seeds) and underwent AS under C-arm guidance. Then, five rabbits were killed from each group at 2, 4, and 8 weeks for further examination. Laboratory tests (including routine blood tests, liver function, kidney function, and electrolytes), gross observations, and tissue changes of Masson/hematoxylin-eosin staining, plus immunohistochemistry of α-SMA, NOX4, and TGF-β were performed at each time point.

RESULTS

All animals underwent AS successfully without procedure-related death, but one animal died at 6 weeks due to severe pulmonary infection in group C. Apart from a transient increase in white blood cells (P < 0.05) and a gradual increase in ROS levels (P < 0.05), other blood test items showed no significant changes (P > 0.05). The brachytherapy injury score increased with irradiation dose accumulation (P < 0.05), but tissue hyperplasia at the stent end in group C was less severe than that in groups A and B (P < 0.05). Airway lateral fibrosis was observed in all groups by histopathologic analysis; however, fibrosis in group C was more severe than that in groups A and B (P < 0.05).

CONCLUSION

The brachytherapy injury score increased with irradiation dose accumulation, while granulation tissue hyperplasia at the stent end was inhibited by ¹²⁵I brachytherapy within 8 weeks.

Characteristics of PSA Bounce after Radiotherapy for Prostate Cancer: A Meta-Analysis

The rate and characteristics of prostate-specific antigen (PSA) bounce post-radiotherapy remain unclear. To address this issue, we performed a meta-analysis. Reports of PSA bounce post-radiotherapy with a cutoff of 0.2 ng/mL were searched by using Medline and Web of Science. The primary endpoint was the occurrence rate, and the secondary endpoints were bounce characteristics such as amplitude, time to occurrence, nadir value, and time to nadir. Radiotherapy modality, age, risk classification, androgen deprivation therapy, and the follow-up period were extracted as clinical variables. Meta-analysis and univariate meta-regression were performed with random-effect modeling. Among 290 search-positive studies, 50 reports including 26,258 patients were identified. The rate of bounce was 31%; amplitude was 1.3 ng/mL; time to occurrence was 18 months; nadir value was 0.5 ng/mL; time to nadir was 33 months. Univariate meta-regression analysis showed that radiotherapy modality (29.7%), age (20.2%), and risk classification (12.2%) were the major causes of heterogeneity in the rate of bounce. This is the first meta-analysis of PSA bounce post-radiotherapy. The results are useful for post-radiotherapy surveillance of prostate cancer patients.