Radiation therapy to the primary in metastatic prostate cancer: palliation only or altering tumor biology?

Indication and perspectives of radiation therapy in the setting of de-novo metastatic prostate cancer

Prostate cancer is the most common cancer and the third leading cause of cancer mortality in men. Each year, approximately 10% of prostate cancers are diagnosed metastatic at initial presentation. The standard treatment option for de-novo metastatic prostate cancer is androgen deprivation therapy with novel hormonal agent or with chemotherapy. Recently, PEACE-1 trial highlighted the benefit of triplet therapy resulting in the combination of androgen deprivation therapy combined with docetaxel and abiraterone. Radiotherapy can be proposed in a curative intent or to treat local symptomatic disease. Nowadays, radiotherapy of the primary disease is only recommended for de novo low-burden/low-volume metastatic prostate cancer, as defined in the CHAARTED criteria. However, studies on stereotactic radiotherapy on oligometastases have shown that this therapeutic approach is feasible and well tolerated. Prospective research currently focuses on the benefit of intensification by combining treatment of the metastatic sites and the primary all together. The contribution of metabolic imaging to better define the target volumes and specify the oligometastatic character allows a better selection of patients. This article aims to define indications of radiotherapy and perspectives of this therapeutic option for de-novo metastatic prostate cancer.

Definitive treatment and risk of death among men diagnosed with metastatic prostate cancer at the Veterans Health Administration

PURPOSE

To assess the potential survival benefit associated with receipt of definitive treatment (radical prostatectomy or radiation), compared to non-definitive treatment (hormonal therapy or chemotherapy) among men with metastatic prostate cancer.

METHODS

A cohort of men diagnosed with metastatic (T4/M1/N1 or T4/M1) prostate cancer from 1999 to 2013 in the Veterans Health Administration were identified and followed to December 28, 2014. All-cause and prostate cancer-specific mortality were evaluated at 10 years for the T4/M1/N1 cohort and 8 years for the T4/M1/ cohort. The association of definitive treatment (radical prostatectomy or radiation), compared to non-definitive (hormonal therapy or chemotherapy) with both all-cause and prostate cancer-specific mortality was assessed using inverse probability of treatment weighted (IPTW) multivariable survival analyses.

RESULTS

The cohort included 2919 with T4/M1/N1 disease and 1479 men with T4/M1 disease. Receipt of definitive treatment was associated with a reduced risk of 10-year all-cause (Hazard Ratio (HR): 0.61; 95% Confidence Interval (CI): 0.57-0.65) and prostate cancer-specific mortality (HR: 0.50; 95% CI: 0.46-0.55) among men diagnosed with T4/M1/N1 met-astatic disease. Definitive treatment was similarly associated with a reduced risk of all-cause (HR: 0.84; 95% CI: 0.77-0.91) and prostate cancer-specific (HR: 0.81; 95% CI: 0.73-0.90) mortality among men diagnosed with T4/M1 only metastatic disease.

CONCLUSIONS

Definitive treatment may improve survival in men diagnosed with metastatic prostate cancer.

Robot-Assisted Radical Prostatectomy for Potential Cancer Control in Patients with Metastatic Prostate Cancer

Recently, cytoreductive prostatectomy for metastatic prostate cancer (mPCa) has been associated with improved oncological outcomes. This study was aimed at evaluating whether robot-assisted radical prostatectomy (RARP) as a form of cytoreductive prostatectomy can improve oncological outcomes in patients with mPCa. We conducted a retrospective study of twelve patients with mPCa who had undergone neoadjuvant therapy followed by RARP. The endpoints were biochemical recurrence-free survival, treatment-free survival, and de novo metastasis-free survival. At the end of the follow-up period, none of the enrolled patients had died from PCa. The 1- and 2-year biochemical recurrence-free survival rates were 83.3% and 66.7%, respectively, and treatment-free survival rates were 75.0% and 56.3%, respectively. One patient developed de novo bone metastases 6.4 months postoperatively, and castration-resistant prostate cancer 8.9 months postoperatively. After RARP, the median duration of recovery of urinary continence was 5.2 months. One patient had severe incontinence (>2 pads/day) 24 months postoperatively. RARP may be a treatment option in patients with mPCa who have achieved a serum prostate-specific antigen level < 0.2 ng/mL, and present without new lesions on imaging.

[Treatment of primary disease for synchronous metastatic prostate cancer]

The management of early metastatic prostate cancer is based on systemic treatment by androgen deprivation therapy with or without chemotherapy or next-generation anti-androgen therapies. Local treatment of the prostate was initially used only to alleviate local symptoms. However, local radiotherapy of the prostate has been the subject of retrospective and prospective studies in patients with better prognostic factors, particularly in oligometastatic status. The results of these studies support that prostate radiotherapy can prolong the survival of patients with a low metastatic burden. This article states the biological bases, the main published and future published studies aimed to embed this strategy to optimize therapeutic management.

Examining initial treatment and survival among men with metastatic prostate cancer: An analysis from the CaPSURE registry

BACKGROUND

New data is emerging to guide initial treatment of patients with metastatic prostate cancer (CaP). This study utilizes the Cancer of the Prostate Strategic Urologic Research Endeavor registry to evaluate variations in survival based on initial treatment received by men with metastatic disease at diagnosis or after progression.

MATERIALS AND METHODS

Cancer of the Prostate Strategic Urologic Research Endeavor is a national registry of men diagnosed with CaP and managed at 43 community, academic, and Veteran's centers. We examined socio-demographic factors, disease biology, initial and subsequent therapy received, and survival among patients who presented with de novo or recurrent metastatic disease stratified by receipt of initial local therapy vs. combined local and hormonal therapy. The outcome was prostate cancer specific mortality (PCSM). We performed Fine and Gray competing risks regression analysis to evaluate the association between timing of metastasis and PCSM, adjusted for age, initial treatment, and subsequent therapy.

RESULTS

Of the 14,753 patients diagnosed with CaP from 1990 to 2016, 669 (5%) had metastatic disease. Among the examined patients, 303 (45%) had metastatic disease at diagnosis and 366 (55%) progressed to metastatic disease. Overall, 461 (69%) were ≥65 years old, 582 (87%) had Medicare, and 227 (34%) had an annual income < $30,000. Prostate-specific antigen at diagnosis was >20 ng/ml for 342 (51%) patients and biopsy Gleason grade was ≥4 + 3 for 386 (58%) patients. Among patients with metastatic disease at diagnosis, 31 (10%) received initial local therapy and 272 (90%) received initial hormonal therapy. Among patients who progressed to metastatic disease, 239 (65%) received initial local therapy and 127 (35%) received initial systemic hormonal therapy. Among patients with metastatic disease, the multivariate competing risks model, after adjusting for sociodemographics, marital status, diagnosis year, and comorbidities, revealed a significantly lower risk of PCSM among patients with de novo vs. recurrent metastatic disease (Hazard Ratio 0.66 (95% Confidence Interval 0.51, 0.85) P = 0.002). In the stratified analysis, no difference was seen for patients treated with initial hormonal vs. combined local and hormonal therapy.

CONCLUSIONS

In this analysis of a nationwide cohort of men treated for CaP with all types of therapy over 25 years, we observed that among men with metastatic CaP, the risk of PCSM was lower for de novo vs. recurrent metastatic disease. Additionally, no difference was observed based on initial treatment with combined local and hormonal therapy vs. hormonal therapy alone.