Predictors of biochemical failure in patients undergoing prostate whole-gland salvage cryotherapy: a novel risk stratification model

Development and internal validation of multivariable prediction models for biochemical failure after MRI-guided focal salvage high-dose-rate brachytherapy for radiorecurrent prostate cancer

Background and purpose

Magnetic resonance-guided focal salvage high-dose-rate brachytherapy (FS-HDR-BT) for radiorecurrent prostate cancer (PCa) shows low toxicity rates. However, biochemical failure (BF) after treatment occurs frequently. We developed two prediction models for BF (Phoenix definition) with the aim of enhancing patient counselling before FS-HDR-BT and during follow-up.

Materials and methods

A prospective cohort of 150 radiorecurrent PCa patients treated with FS-HDR-BT between 2013 and 2020 was used for model development and internal validation. Multivariable Cox Proportional Hazards regression was applied. For model 1, only pre-salvage variables were included as candidate predictors. For model 2, additional (post-)salvage characteristics were tested. After calibration, nomograms and webtools were constructed. Finally, three risk groups were identified.

Results

Sixty-one patients (41%) experienced BF. At baseline (model 1), age, gross tumour volume, pre-salvage PSA, and pre-salvage PSA doubling time (PSADT) were predictive of BF. During follow-up (model 2), age, pre-salvage PSA and PSADT, seminal vesicle involvement, post-salvage time to PSA nadir, and percentage PSA reduction were predictive of BF. The adjusted C-statistics were 0.73 (95% CI: 0.66-0.81) and 0.84 (95% CI: 0.78-0.90), respectively, with acceptable calibration. Estimated 2-year biochemical disease-free survival for the low-, intermediate-, and high-risk groups were 84%, 70%, and 31% (model 1), and 100%, 71%, and 5% (model 2).

Conclusion

Two models are provided for prediction of BF in patients with radiorecurrent PCa treated with FS-HDR-BT. Based on pre- and post-salvage characteristics, we are able to identify patients with a high risk of BF. These findings can aid patient counselling for FS-HDR-BT.

Does adding local salvage ablation therapy provide survival advantage for patients with locally recurrent prostate cancer following radiotherapy? Whole gland salvage ablation post-radiation failure in prostate cancer

INTRODUCTION

Some men who experience prostate cancer recurrence post-radiotherapy may be candidates for local salvage therapy, avoiding and delaying systemic treatments. Our aim was to assess the impact of clinical outcomes of adding salvage local treatment in prostate cancer patients who have failed radiation therapy.

METHODS

Following radiation biochemical failure, salvage transperineal cryotherapy (sCT, n=186), transrectal high intensity focused ultrasound ablation (sHIFU, n=113), or no salvage treatment (NST, identified from the pan-Canadian Prostate Cancer Risk Stratification [ProCaRS] database, n=982) were compared with propensity-score matching. Primary endpoints were cancer-specific survival (CSS) and overall survival (OS).

RESULTS

Median followup was 11.6, 25.1, and 14.3 years following NST, sCT, and sHIFU, respectively. Two propensity score-matched analyses were performed: 1) 196 NST vs. 98 sCT; and 2) 177 NST vs. 59 sHIFU. In the first comparison, there were 78 deaths and 49 prostate cancer deaths for NST vs. 80 deaths and 24 prostate cancer deaths for sCT. There were significant benefits in CSS (p<0.001) and OS (p<0.001) favoring sCT. In the second comparison, there were 52 deaths (31 from prostate cancer) for NST vs. 18 deaths (nine from prostate cancer) for sHIFU. There were no significant differences in CSS or OS possibility attributed to reduced sample size and shorter followup of sHIFU cohort.

CONCLUSIONS

In select men with recurrent prostate cancer post-radiation, further local treatment may lead to benefits in CSS. These hypothesis-generating findings should ideally be validated in a prospective clinical trial setting.

Long-term outcomes of two ablation techniques for treatment of radio-recurrent prostate cancer

BACKGROUND

In men with recurrence of prostate cancer post radiation therapy, further treatment remains a challenge. The default salvage option of androgen-deprivation therapy (ADT) has adverse effects. Alternatively, selected men may be offered salvage therapy to the prostate. Herein, we present long-term oncological outcomes of two whole-gland ablation techniques, cryotherapy (sCT) and high-intensity-focused ultrasound (sHIFU).

METHODS

Men undergoing sCT (1995-2004) and sHIFU (2006-2018) at Western University were identified. Oncological endpoints included biochemical recurrence (BCR), ADT initiation, metastases, castration resistance (CRPC), and prostate cancer-specific mortality (PCSM). Survival analysis with competing risks of mortality was performed. Multivariable analysis was performed using Fine and Gray regression.

RESULTS

A total of 187 men underwent sCT and 113 sHIFU. Mean (SD) age of the entire cohort was 69.9 (5.9 years), median pre-radiation PSA 9.6 ng/ml (IQR 6.1-15.2), and pre-salvage PSA 4.5 ng/ml (IQR 2.8-7.0). Median total follow-up was 116 months (IQR 67.5-173.8). A total of 170 (57.6%) developed BCR, 68 (23.4%) metastases, 143 (49.3%) were started on ADT, 58 (20.1%) developed CRPC, and 162 (56%) patients died of which 59 (36.4%) were of prostate cancer. On multivariable analysis, sHIFU (HR 1.65, 95% CI 1.15-2.36, p = 0.006) and pre-salvage PSA (HR 1.09, 95% CI 1.06-1.13, p < 0.0001) were associated with a higher risk of BCR. Similarly, sHIFU patients had a higher risk of CRPC (HR 2.31, 95% CI 1.23-4.35, p = 0.009). The cumulative incidence (for both treatments) of PCSM was 16.5% (95% CI 12.2-21.4%) at 10 years and 28.4% (95% CI 22.1-34.9%) at 20 years, with no difference between treatment modalities. Pre-salvage PSA was a common predictor for the measured oncological outcomes.

CONCLUSIONS

Although sHIFU had higher BCR and CRPC rates, there were no differences in PCSM when compared with sCT. The long-term oncological data on two ablation techniques highlighted that only 50% of patients started ADT after 10-year follow-up.

Oncological outcomes of salvage cryotherapy after primary radiation therapy vs. primary cryotherapy: 10-year experience at a large Canadian referral center

INTRODUCTION

Salvage cryotherapy is a guideline-recommended treatment of localized prostate cancer recurrence after radiation therapy. There is little published evidence analyzing the outcomes of salvage cryotherapy for recurrent prostate cancer following different primary therapy energy modalities.

METHODS

We performed a retrospective analysis of patients who received whole gland salvage cryotherapy from 2007-2017 at a large tertiary referral center after either primary radiation therapy (RT) or primary whole gland cryotherapy. Primary outcome was biochemical failure, defined as per the Phoenix criteria (prostate-specific antigen [PSA] nadir + 2.0 ng/ml). Secondary outcomes included time to biochemical failure and development of metastatic disease.

RESULTS

Fifty-eight of 391 patients who received cryotherapy were identified as having received salvage cryotherapy (after RT, n=37; after primary cryotherapy, n=21). Biochemical recurrence occurred in 21 (57%) patients with previous RT and in 17 (81%) patients with previous cryotherapy (p=0.001). Median time to biochemical recurrence was 18 months for patients with previous RT and 13 months for patients with previous cryotherapy (p=0.002). The biochemical-free survival rate for primary radiation therapy patients was 71% at two years compared to 23% at two years for patients who underwent primary cryotherapy (p<0.01). There was no difference in the development of metastatic disease between groups (19% vs. 18%, cryo vs. radiation, p=0.34).

CONCLUSIONS

These results suggest that salvage cryotherapy may offer more durable oncological control to patients after radiation compared to primary cryotherapy, with a lower rate and longer duration before biochemical recurrence.

Salvage Cryoablation for Radiorecurrent Prostate Cancer: Initial Experience at a Regional Health Care System

CONTEXT

Local recurrence after radiotherapy for prostate cancer remains challenging to treat effectively. Although oncologic control is highest with salvage prostatectomy, the procedure is associated with substantial morbidity.

OBJECTIVE

To identify factors associated with successful salvage cryoablation for radiorecurrent prostate cancer.

DESIGN

We retrospectively reviewed the medical records of patients who underwent salvage cryoablation at our institution between 2005 and 2015. All patients had biopsy-proven local recurrence after radiotherapy. Patients with seminal vesicle invasion or metastases were excluded. Complete follow-up was obtained for all patients.

MAIN OUTCOME MEASURES

Primary study endpoint was biochemical progression-free survival based on the Phoenix criteria.

RESULTS

Seventy-five patients underwent salvage cryotherapy. Mean patient age was 69.3 years. The overall biochemical salvage rate was 50.7% at a median follow-up of 3.9 years. The following factors were independently associated with successful cryotherapy: Precryotherapy Gleason score of 3 + 3 or 3 + 4, low precryotherapy prostate-specific antigen (PSA), low precryotherapy PSA density, longer time to PSA nadir after radiotherapy, and low postcryotherapy PSA nadir. A postcryotherapy PSA nadir of 0.5 ng/mL or less was associated with a biochemical progression-free survival of 79.7% at 3 years and 64.7% at 5 years, whereas a postcryotherapy PSA nadir above 0.5 was associated with a biochemical progression-free survival of 5.6% at 3 years and 0% at 5 years (p < 0.0001).

CONCLUSION

Approximately 50% of the patients achieved biochemical salvage with cryoablation at 5 years. Nadir PSA after salvage was the strongest predictor of biochemical progression-free survival in our cohort.

[Percutaneous MR-guided prostate cancer cryoablation: Predictive factors and oncologic outcomes]

OBJECTIVE

To determine the pejorative predictive factors on oncologic outcomes of percutaneous MR-guided whole gland prostate cancer cryoablation (CA).

METHODS

Medical records of patients treated from 2009 to 2012, to assess medium-term oncologic outcomes, were reviewed. Prostate biopsies were performed in local recurrence suspicion (biochemical failure, MR follow-up failure).

RESULTS

Among 18 patients, mean age of 72.6 (61-78), 2 (11 %) and 7 (38.9 %) biological and reported biopsy-proven local recurrence respectively with our initial technic of CA. Mean follow-up and recurrence were 56.3 (±21.7) and 20.7 (±13.9) months respectively. A previous treatment of prostate cancer (P=0.5), pre-treatment PSA (P=0.2), pre-treatment Gleason/ISUP score (P=0.4), nadir PSA post-CA (P=0.22) were not associated with recurrence. Bilateral positive cores appears as a pejorative predictive factor (P=0.04). However mean pre-treatment positive cores percentage, 25 (±16.5) in responding patients versus 40.7 (±25.2) in case of recurrence, and maximum percentage of cancer extent in each positive core, 10.6 (±9.3) in responding patients versus 18.7 (±16.5) in case of recurrence, seemed associated with local recurrence after prostate CA but our analysis wasn't able to find a difference (P=0.09 and P=0.3 respectively) due to a lack of power.

CONCLUSION

Bilateral positive cores appears as a pejorative predictive factor. In our experience, important tumor volume seem to be a pejorative predictive factor for oncologic outcomes after PCA whereas treatment, PSA, Gleason/ISUP score, nadir PSA are not.

LEVEL OF EVIDENCE

4.

[Salvage cryotherapy of prostate cancer after failed external radiotherapy and brachytherapy: Morbidity and mid-term oncological results]

OBJECTIVE

To study the oncologic and functional results of salvage cryotherapy after failure of external radiotherapy and brachytherapy.

MATERIALS AND METHODS

Patients treated by total salvage cryotherapy (3rd generation) in 2 centers (Groupe Hospitalier Saint-Joseph in Paris and Clinique Jule-Verne Nantes) in between January 2008 and April 2016 were included. The biochemical recurrence-free survival (BRFS) was calculated using the Phoenix criteria (PSA>nadir+2ng/mL). The functional results were assessed clinically.

RESULTS

Ninety-seven patients with an average follow up of 39.4months were evaluated retrospectively. The 5-year biochemical recurrence-free survival (5y-BRFS) among all patients was 58.1% (IC à 95% [45.9-68.5]). Low and intermediate risk patients (d'Amico classification) were less prone to biochemical recurrence than high risk (81.05% (IC à 95% [64.1-90.5]) 5y-BRFS as opposed to 35.09% (IC à 95% [20.1-50.4]) respectively) (P<0.0001). As were patients with a Gleason score≤7 75.35% (IC à 95% [59.7-85.6]) compared to 32.31% (IC à 95% [16.5-49.2]) for higher Gleason (>7 scores [P=0.0002]). A Gleason score>7 (OR=6.9; P=0.002), PSA nadir>1ng/mL (OR=25.8; P=0.0026) and peri-urethral invasion (OR=35.8; P<0.001) were major risk factors for local recurrence in univariate analysis. In multivariate analysis, only PSA nadir>1ng/mL (OR=12.9; P=0.042) and peri-urethral invasion (OR=21.6; P=0.0003) remain major risk factors for recurrence. About 13 (16.46%) patients were incontinent of which 3 (3.79%) required placement of an artificial urinary sphincter. Erectile dysfunction was present in 66 (83.5%) patients. Recto-urethral fistula was uncommon in 1 patient (1.27%).

CONCLUSION

Salvage cryotherapy after failure of external radiotherapy and brachytherapy is a reliable and reproducible technique with promising oncological and functional results. Study of prognostic factors will help better select eligible patients in the future.

LEVEL OF EVIDENCE

4.

Predictors of biochemical recurrence after primary focal cryosurgery (hemiablation) for localized prostate cancer: A multi-institutional analytic comparison of Phoenix and Stuttgart criteria

BACKGROUND

The Phoenix definition (PD) and Stuttgart definition (SD) designed to determine biochemical recurrence (BCR) in patients with postradiotherapy and high-intensity focused ultrasound organ-confined prostate cancer are being applied to follow patients after cryosurgery. We sought to identify predictors of BCR using the PD and SD criteria in patients who underwent primary focal cryosurgery (PFC).

MATERIALS AND METHODS

We performed a retrospective review of patients who underwent PFC (hemiablation) at 2 referral centers from 2000 to 2014. Patients were followed up with serial prostate-specific antigen (PSA). PSA levels, pre- and post-PFC biopsy, Gleason scores, number of positive cores, and BCR (PD = [PSA nadir+2ng/ml]; SD = [PSA nadir+1.2ng/ml]) were recorded. Patients who experienced BCR were biopsied, monitored carefully or treated at the discretion of the treating urologist. Cox regression and survival analyses were performed to assess time to BCR using PD and SD.

RESULTS

A total of 163 patients were included with a median follow-up of 36.6 (interquartile range: 18.9-56.4) months. In all, 64 (39.5%) and 98 (60.5%) experienced BCR based on PD and SD, respectively. On multivariable Cox regression, the number of positive pre-PFC biopsy cores was an independent predictor of both PD (hazard ratio [HR] = 1.4, P = 0.001) and SD (HR = 1.3, P = 0.006) BCRs. Post-PFC PSA nadir was an independent predictor of BCR using the PD (HR = 2.2, P = 0.024) but not SD (HR = 1.4, P = 0.181). Survival analysis demonstrated a 3-year BCR-free survival rate of 56% and 36% for PD and SD, respectively. Of those biopsied after BCR, 14/26 (53.8%) using the PD and 18/35 (51.4%) using the SD were found to have residual/recurrent cancer. Of those with prostate cancer on post-PFC biopsy, 57.1% of those with BCR by the PD and 66.7% of those with BCR by the SD were found to have a Gleason score ≥7.

CONCLUSION

Both the PD and the SD may be used to determine BCR in post-PFC patients. However, the ideal definition of BCR after PFC remains to be elucidated.

A pretreatment nomogram for prediction of biochemical failure after primary cryoablation of the prostate

BACKGROUND

To create a predictive nomogram for biochemical failure following primary whole-gland cryoablation of the prostate for localized prostate cancer (LPCa).

METHODS

We retrospectively analyzed 2,242 patients from the Cryo On-Line Database (COLD) who were treatment naive and had undergone primary whole gland cryoablation of the prostate for biopsy-confirmed LPCa. Kaplan-Meier (KM) curves estimating 5 year biochemical progression-free survival (bPFS) were generated. Multivariable Cox proportional hazards analysis (CoxPH) was performed in order to construct the nomogram. The nomogram was internally validated using the bootstrap technique.

RESULTS

Overall, the KM estimated 5 year bPFS was 72.8%. Stratified by D'Amico risk, The KM estimated 5 year bPFS was 82.6%, 71.1%, and 57.8% for low-, intermediate-, and high-risk groups, respectively. Statistically significant predictors of biochemical outcomes from CoxPH analysis were pre-treatment prostate specific antigen (PTPSA) (P < 0.001), total prostate volume (P = 0.004), clinical stage (P = 0.034), and Gleason score (0.004). A nomogram for predicted 5 year biochemical progression free probability was constructed with a concordance index of 0.652. An online risk calculator was also generated.

CONCLUSIONS

To the best of our knowledge, this is the first predictive nomogram for biochemical outcomes after primary whole gland cryoablation of the prostate using socio-demographic, pretreatment, clinical, and prostate biopsy data. Our nomogram and online risk calculator can guide both patients and urologists for shared decision making regarding definitive treatment options.

Salvage focal prostate cryoablation for locally recurrent prostate cancer after radiotherapy: initial results from the cryo on-line data registry

BACKGROUND

Several investigators have tried to apply salvage focal prostate cryoablation to small numbers of patients with biopsy-proven unilateral recurrent prostate cancer (PCa) after radiotherapy with the aim of decreasing complications of salvage cryoablation. We report contemporary outcomes of salvage focal cryoablation for locally recurrent PCa after radiotherapy within the Cryo On-Line Data (COLD) Registry.

METHODS

We queried the COLD Registry to identify patients diagnosed as locally recurrent PCa after radiotherapy and treated with salvage focal cryoablation. Patients with hormone ablation after cryotherapy were excluded. The biochemical disease-free survival and morbidities were analyzed. Biochemical failure was defined using the Phoenix definition.

RESULTS

From 2002 to 2012, 91 patients with biopsy-proven radio-recurrent PCa underwent salvage focal cryoablation with curative intent. The biochemical disease-free survival rates were 95.3%, 72.4%, and 46.5% at 1, 3, and 5 years, respectively. Positive biopsies after salvage focal cryoablation were observed in four of 14 patients who underwent biopsy (28.6%). Rectourethral fistula was observed in three cases (3.3%). Urinary retention was observed in six cases (6.6%). Incontinence (requiring pad use) was reported in five cases (5.5%). Intercourse was reported in 10 of 20 patients (50%) who reported potency before salvage focal cryoablation.

CONCLUSIONS

The outcomes from this observational study indicate that salvage focal cryoablation can be an effective treatment with encouraging potency preservation for patients with locally recurrent PCa after radiotherapy. However, other morbidity including rectourethral fistula and incontinence are not clearly lower than for patients treated with salvage whole gland cryoablation. Studies with longer follow-up, more patients, and direct comparison to salvage whole gland cryoablation are needed before recommending salvage focal cryoablation as a standard treatment option for these patients.