Prostate-specific antigen density is predictive of outcome in suboptimal prostate seed brachytherapy

An external validation of the Candiolo nomogram in a cohort of prostate cancer patients treated by external-beam radiotherapy

Background

the aim of this study is to perform an external validation for the Candiolo nomogram, a predictive algorithm of biochemical and clinical recurrences in prostate cancer patients treated by radical Radiotherapy, published in 2016 on the journal “Radiation Oncology”.

Methods

561 patients, treated by Radiotherapy with curative intent between 2003 and 2012, were classified according to the five risk-classes of the Candiolo nomogram and the three risk-classes of the D’Amico classification for comparison. Patients were treated with a mean prostatic dose of 77.7 Gy and a combined treatment with Androgen-Deprivation-Therapy in 76% of cases. The end-points of the study were biochemical-progression-free-survival (bPFS) and clinical-Progression-Free-Survival (cPFS). With a median follow-up of 50 months, 56 patients (10%) had a biochemical relapse, and 30 patients (5.4%) a clinical progression. The cases were divided according to D’Amico in low-risk 21%, intermediate 40%, high-risk 39%; according to Candiolo very-low-risk 24%, low 37%, intermediate 24%, high 10%, very-high-risk 5%. Statistically, the Kaplan-Meier survival curves were processed and compared using Log-Rank tests and Harrell-C concordance index.

Results

The 5-year bPFS for the Candiolo risk-classes range between 98 and 38%, and the 5-year cPFS between 98 and 50% for very-low and very-high-risk, respectively. The Candiolo nomogram is highly significant for the stratification of both bPFS and cPFS (P < 0.0001), as well as the D’Amico classification (P = 0.004 and P = 0.001, respectively). For the Candiolo nomogram, the C indexes for bPFS and cPFS are 75 and 80%, respectively, while for D’Amico classification they are 64 and 69%, respectively. The Candiolo nomogram can identify a greater number of patients with low and very-low-risk prostate cancer (61% versus 21% according to D’Amico) and it better picks out patients with high and very-high-risk of recurrence, equal to only 15% of the total cases but subject to 48% (27/56) of biochemical relapses and 63% (19/30) of clinical progressions.

Conclusions

the external validation of the Candiolo nomogram was overall successful with C indexes approximately 10% higher than the D’Amico control classification for bPFS and cPFS. Therefore, its clinical use is justified in prostate cancer patients before radical Radiotherapy.

Trial registration Retrospectively registered.

Low-dose-rate prostate brachytherapy: 4-8 week postimplant prostate-specific antigen a novel predictor of biochemical failure-free survival

PURPOSE

The purpose of this study was to determine the relationship between patient, disease, and treatment variables and biochemical failure-free survival (bFFS) following low-dose-rate prostate brachytherapy (LDR-BT).

METHODS AND MATERIALS

Data from 624 consecutive patients who received LDR-BT for localized prostate cancer between 2002 and 2012 at a single institution were collected for various patient, disease, and treatment characteristics including a 4-8 week postimplant PSA (4-8wkPSA). Subgroup analysis was stratified by risk category and treatment regimen. Analysis was performed using Kaplan-Meier survival curves, Cox proportional hazard ratios (HRs), and receiver-operator characteristic curves.

RESULTS

A total of 624 consecutive patients were included with followup time of 4.0 ± 3.1 years. Predictors of bFFS included PSA nadir and 4-8wkPSA (HR = 2.48, p = 0.000 and HR = 1.24, p = 0.000, respectively) for total population. Diabetes mellitus (p = 0.026), chronic obstructive pulmonary disease (p = 0.000), alcohol use (p = 0.024), and age (p = 0.002) were predictors for specific subgroups. Receiver-operator characteristic curves 4-8wkPSA were found to be significant (p = 0.036).

CONCLUSION

4-8wkPSA is a novel predictor of bFFS for patients receiving LDR-BT across several risk categories and treatment regimens with potential clinical utility as a prognostic indicator. Certain comorbidities and exposure histories also demonstrated significant relationships with bFFS including chronic obstructive pulmonary disease, diabetes mellitus, age, alcohol history, proton pump inhibitor use, PSA nadir, and PSA density.

Is intraoperative real-time dosimetry in prostate seed brachytherapy predictive of biochemical outcome?

Purpose

To analyze intraoperative (IO) dosimetry using transrectal ultrasound (TRUS), performed before and after prostate low-dose-rate brachytherapy (LDR-BT), and compare it to dosimetry performed 30 days following the LDR-BT implant (Day 30).

Material and methods

A total of 236 patients underwent prostate LDR-BT using ¹²⁵I that was performed with a three-dimensional TRUS-guided interactive inverse preplanning system (preimplant dosimetry). After the implant procedure, the TRUS was repeated in the operating room, and the dosimetry was recalculated (postimplant dosimetry) and compared to dosimetry on Day 30 computed tomography (CT) scans. Area under curve (AUC) statistics was used for models predictive of dosimetric parameters at Day 30.

Results

The median follow-up for patients without BF was 96 months, the 5-year and 8-year biochemical recurrence (BR)-free rate was 96% and 90%, respectively. The postimplant median D₉₀ was 3.8 Gy lower (interquartile range [IQR], 12.4-0.9), and the V₁₀₀ only 1% less (IQR, 2.9-0.2%) than the preimplant dosimetry. When comparing the postimplant and the Day 30 dosimetries, the postimplant median D₉₀ was 9.6 Gy higher (IQR [–] 9.5-30.3 Gy), and the V₁₀₀ was 3.2% greater (0.2-8.9%) than Day 30 postimplant dosimetry. The variables that best predicted the D₉₀ of Day 30 was the postimplant D₉₀ (AUC = 0.62, p = 0.038). None of the analyzed values for IO or Day 30 dosimetry showed any predictive value for BR.

Conclusions

Although improving the IO preimplant and postimplant dosimetry improved dosimetry on Day 30, the BR-free rate was not dependent on any dosimetric parameter. Unpredictable factors such as intraprostatic seed migration and IO factors, prevented the accurate prediction of Day 30 dosimetry.