THE NATURAL HISTORY OF ANDROGEN INDEPENDENT PROSTATE CANCER

Cardiovascular outcomes among patients with castration-resistant prostate cancer: A comparative safety study using US administrative claims data

BACKGROUND

Cardiovascular conditions are the most prevalent comorbidity among patients with prostate cancer, regardless of treatment. Additionally, cardiovascular risk has been shown to increase following exposure to certain treatments for advanced prostate cancer. There is conflicting evidence on risk of overall and specific cardiovascular outcomes among men treated for metastatic castrate resistant prostate cancer (CRPC). We, therefore, sought to compare incidence of serious cardiovascular events among CRPC patients treated with abiraterone acetate plus predniso(lo)ne (AAP) and enzalutamide (ENZ), the two most widely used CRPC therapies.

METHODS

Using US administrative claims data, we selected CRPC patients newly exposed to either treatment after August 31, 2012, with prior androgen deprivation therapy (ADT). We assessed incidence of hospitalization for heart failure (HHF), ischemic stroke, and acute myocardial infarction (AMI) during the period 30-days after AAP or ENZ initiation to discontinuation, outcome occurrence, death, or disenrollment. We matched treatment groups on propensity-scores (PSs) to control for observed confounding to estimate the average treatment effect among the treated (AAP) using conditional Cox proportional hazards models. To account for residual bias, we calibrated our estimates against a distribution of effect estimates from 124 negative-control outcomes.

RESULTS

The HHF analysis included 2322 (45.1%) AAP initiators and 2827 (54.9%) ENZ initiators. In this analysis, the median follow-up times among AAP and ENZ initiators (after PS matching) were 144 and 122 days, respectively. The empirically calibrated hazard ratio (HR) estimate for HHF was 2.56 (95% confidence interval [CI]: 1.32, 4.94). Corresponding HRs for AMI and ischemic stroke were 1.94 (95% CI: 0.90, 4.18) and 1.25 (95% CI: 0.54, 2.85), respectively.

CONCLUSIONS

Our study sought to quantify risk of HHF, AMI and ischemic stroke among CRPC patients initiating AAP relative to ENZ within a national administrative claims database. Increased risk for HHF among AAP compared to ENZ users was observed. The difference in myocardial infarction did not attain statistical significance after controlling for residual bias, and no differences were noted in ischemic stroke between the two treatments. These findings confirm labeled warnings and precautions for AAP for HHF and contribute to the comparative real-world evidence on AAP relative to ENZ.

International survey of androgen deprivation therapy (ADT) for non-metastatic prostate cancer in 19 countries

Background

Continuous androgen deprivation therapy (CADT) is commonly used for patients with non-metastatic prostate cancer as primary therapy for high-risk disease, adjuvant therapy together with radiation or for recurrence after initial local therapy. Intermittent ADT (IADT), a recently developed alternative strategy for providing ADT, is thought to potentially reduce adverse effects, but little is known about practice patterns relating to it. We aimed to describe factors related to physicians’ ADT use and modality for patients with non-metastatic prostate cancer.

Methods

A 45 min online survey was completed by urologists and oncologists responsible for treatment decisions for non-metastatic prostate cancer from 19 countries with high or increasing prevalence of non-metastatic prostate cancer.

Results

There were 441 treating physicians who completed the survey which represented 99 177 patients with prostate cancer under their care, of which 76 386 (77%) had non-metastatic prostate cancer. Of patients with non-metastatic prostate cancer, 38% received ADT (37% gonadotropin-releasing hormone (GnRH), 2% orchiectomy); among patients on GnRH, 54% received CADT (≥6 without >3 months interruption), 23% IADT and 23% <6 months. Highest rates of ADT were reported among oncologists (62%) and in Eastern Europe (Czech Republic, Hungary and Poland). Prostate-specific antigen (PSA) levels (65%), Gleason score (52%) and treatment guidelines (48%) were the most common reasons for CADT whereas PSA levels (54%), patient request (48%), desire to maintain sexual function (40%), patient age and comorbidities (38%) were cited most frequently as reasons for IADT.

Conclusions

This international survey with 441 treating physicians from 19 countries showed that ADT is commonly used in treating patients with non-metastatic prostate cancer, and type of ADT is influenced by high-risk criteria (PSA and Gleason), treatment guidelines and patient preferences. IADT use was primarily driven by PSA levels, patient request and patient age/comorbidities, likely reflecting an attempt to minimise adverse effects of ADT in patients with lower risk tumours.

Shifting paradigms in the estimation of survival for castration-resistant prostate cancer: A tertiary academic center experience

OBJECTIVES

Castration-resistant prostate cancer (CRPC) has retained a guarded prognosis, with historical survival estimates of 18 to 24 months. However, the landscape of available therapy has changed, and the emphasis has altered from supportive to active treatment. Few large series from real-world populations exist in the contemporary era with fully mature survival data to confirm the indication based on clinical trials that patients with CRPC are surviving far longer than the historical estimates. We aim to review a large patient cohort with CRPC and provide mature survival data.

METHODS AND MATERIALS

Using the electronic histopathology database at Queen Elizabeth Hospital, Birmingham, UK, all prostate-specific antigentest results between April 2006 and September 2007 were extracted, and patients satisfying the American Society for Radiation Oncology (ASTRO) definition of hormone failure were identified. Electronic records were reviewed and variables were collected, including survival, treatment, biochemistry, histopathology, and demographics. Probability of survival, and of developing metastasis or CRPC, was determined using the Kaplan-Meier method. Patients were stratified into 3 groups, namely, D0--no metastasis at diagnosis but later appearance, D1--no metastasis at diagnosis or at last follow-up, and D2--metastasis at diagnosis.

RESULTS

From 8,062 patient-prostate-specific antigen episodes, we identified 447 patients meeting the criteria. A notes review revealed 147 patients with CRPC. Median overall survival (OS) from diagnosis was 84.7 months (95% CI: 73-89), and 129 deaths had occurred (88%). Median OS from diagnosis for D0, D1, and D2 patients was 100.4, 180.1, and 58.9 months, respectively (P< 0.0001), and median OS from CRPC was 40 months (95% CI: 31-58), 82.9 (95% CI: 72-94; P = 0.0125), and 38.7 months (95% CI: 33-46), respectively. One-quarter of patients survived 6 years after development of CRPC. Metastasis is the key prognostic event.

CONCLUSIONS

Some current international guidelines quote ≤19 months as a survival figure for patients with metastatic CRPC. In our study, median survival is more than double this. We have shown survival more than previously reported figures and believe that these data benefit clinicians and patients in understanding prognosis and treatment choices. Importantly, our patients were diagnosed before the current wave of novel therapeutics for CRPC, so survival for men diagnosed today may be more than our findings.

Survival and clinical metastases among prostate cancer patients treated with androgen deprivation therapy in Sweden

OBJECTIVES

To examine the incidence of metastases and clinical course of prostate cancer patients who are without confirmed metastasis when initiating androgen deprivation therapy (ADT).

METHODS

Retrospective cohort study conducted using electronic medical records from Swedish outpatient urology clinics linked to national mandatory registries to capture medical and demographic data. Prostate cancer patients initiating ADT between 2000 and 2010 were followed from initiation of ADT to metastasis, death, and/or end of follow-up.

RESULTS

The 5-year cumulative incidence (CI) of metastasis was 18%. Survival was 60% after 5 years; results were similar for bone metastasis-free survival. The 5-year CI of castration-resistant prostate cancer (CRPC) was 50% and the median survival from CRPC development was 2.7 years. Serum prostate-specific antigen (PSA) levels and PSA doubling time were strong predictors of bone metastasis, any metastasis, and death.

CONCLUSION

This study provides understanding of the clinical course of prostate cancer patients without confirmed metastasis treated with ADT in Sweden. Greater PSA values and shorter PSA doubling time (particularly ≤ 6 months) were associated with increased risk of bone metastasis, any metastasis, and death.

[Recomendations on the management of controversies in advanced castrate-resistant prostate cancer]

CONTEXT

Controversies and uncertainties among integral management of advanced castration resistant prostate cancer continue to exist despite the number of evidence based clinical practice guidelines published with high international consensus.

OBJECTIVE

To develop a document that reviews the management of controversies in advanced castration resistant prostate cancer, with recommendations from the definition, to the management in hormonal maneuvers, first-line treatment and second-line with new treatments as cabazitaxel or abirarerone and the multidisciplinary approach of the pathology with the goal of finding the most efficient, best time to act and safety.

EVIDENCE ACQUISITION

Two meetings of a multidisciplinary group of experts involved in the management of this disease (Oncologist and Urologist) where pooled analysis of original literature and reached consensus document of recommendations on castration resistant prostate cancer, reviewing and attempting to address the current controversies of the disease.

EVIDENCE SYNTHESIS

This document is endorsed by the corresponding Scientific Associations and Working Groups involved in the current management of Genitourinary Tumours: the Spanish Association of Urology (AEU) with the Uro-Oncoloy Group (GUO) and the Spanish Oncology of Genitourinary Group (SOGUG).

CONCLUSIONS

With the adaptation and implementation of this Document of Recommendations for clinical practice are available for the first time, a real road map for quality, efficiency and safety in the management of patients with CRPC.

Significant associations of prostate-specific antigen nadir and time to prostate-specific antigen nadir with survival in prostate cancer patients treated with androgen-deprivation therapy

OBJECTIVE

The influence of prostate-specific antigen (PSA) kinetics on the outcome of metastatic prostate cancer (PCa) after androgen-deprivation therapy (ADT) remains poorly characterised. We evaluated the prognostic significance of PSA nadir and time to PSA nadir as well as their interactive effect on prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM) after ADT.

METHODS

A total of 650 men with advanced or metastatic PCa treated with ADT were studied. The prognostic significance of PSA nadir and time to PSA nadir on PCSM and ACM were analysed using Kaplan-Meier analysis and the Cox regression model.

RESULTS

On multivariate analysis, clinical M1 stage, Gleason Score 8-10, PSA nadir ≥ 0.2 ng/ml and time to PSA nadir < 10 months were independent predictors of PCSM and ACM. The combined analysis showed that patient with higher PSA nadir and shorter time to PSA nadir had significantly higher risk of PCSM and ACM compared to those with lower PSA nadir and longer time to PSA nadir (hazard ratios = 6.30 and 4.79, respectively, all P < 0.001).

CONCLUSIONS

Our results suggest that higher PSA nadir level and faster time to reach PSA nadir after ADT were associated with shorter survival for PCa.

Impact of prostate-specific antigen (PSA) nadir and time to PSA nadir on disease progression in prostate cancer treated with androgen-deprivation therapy

BACKGROUND

The influence of PSA kinetics on the outcome of metastatic prostate cancer after androgen deprivation therapy (ADT) is not well understood. We evaluated the prognostic significance of PSA nadir and time to PSA nadir as well as their potential interactive effect on the progression of disease after ADT.

METHODS

A total of 650 men with advanced or metastatic prostate cancer treated with ADT were studied. The prognostic significance of PSA nadir and time to PSA nadir on disease progression were analyzed using Kaplan-Meier analysis and the Cox regression model.

RESULTS

We found that both PSA nadir and time to PSA nadir were independent and significant predictors of disease progression. Patients with higher PSA nadir (≥0.2 ng/ml) and shorter time to PSA nadir (<10 months) had significant shorter time to disease progression after adjusting for other covariates. The combined analyses showed a potential synergistic effect of these two variables on disease progression. Patient with higher PSA nadir and shorter time to PSA nadir had significantly higher risk for disease progression compared to those with lower PSA nadir and longer time to PSA nadir (Hazard Ratios (HR) = 3.11, P < 0.001).

CONCLUSIONS

We concluded that both PSA nadir and time to PSA nadir are significant predictors of disease progression for prostate cancer patients receiving ADT.

Significant associations of prostate cancer susceptibility variants with survival in patients treated with androgen-deprivation therapy

Androgen-deprivation therapy (ADT) is the most common therapy for advanced prostate cancer, but the prognosis significantly differs among individuals. In this study, we evaluated recently identified 19 prostate cancer susceptibility variants as prognostic predictors for the survival after ADT. A total of 601 prostate cancer patients treated with ADT were enrolled in this study cohort. The prognostic significance of the prostate cancer risk variants on disease progression, prostate cancer-specific mortality (PCSM) and all-cause mortality (ACM) after ADT were assessed by Kaplan-Meier analysis and Cox regression model. Two polymorphisms, rs16901979 and rs7931342, were significantly associated with PCSM (p = 0.005 for rs16901979 and p = 0.038 for rs7931342), and rs16901979 was also associated with ACM (p = 0.003) following ADT. Although the effect of rs7931342 was attenuated after controlling for other known clinical prognostic factors, rs16901979 remained a significant predictor for PCSM and ACM after ADT (p = 0.002). Moreover, the addition of the rs16901979 status in current clinical staging system further enhanced the risk prediction on PCSM and ACM particularly for the high-risk patients with distant metastasis (p < 0.017). In conclusion, this is the first study showing that prostate cancer risk variants, such as rs16901979, might improve outcome prediction following ADT, thus allowing identification of high-risk patients who might benefit from appropriate adjuvant therapy.

Association of circulating tumor cells with tumor-related methylated DNA in patients with hormone-refractory prostate cancer

OBJECTIVES

To assess whether circulating tumor cells with tumor-related methylated DNA can be used to predict survival in patients with hormone-refractory prostate cancer.

METHODS

Blood samples from 76 patients with hormone-refractory prostate cancer were analyzed. Circulating tumor cells were enumerated with the CellSearch System in whole blood. This system was developed using an epithelial cell adhesion molecule antibody-based immunomagnetic capture and automated staining methodology. Hypermethylation at adenomatosis polyposis coli, glutathione-S-transferase-pi, prostaglandin-endoperoxide synthase 2, multidrug resistance 1 and Ras association domain family 1 isoform A was analyzed using a sensitive SYBR green methylation-specific polymerase chain reaction. Patient charts were retrospectively examined.

RESULTS

Median overall survival time was 19.3 months (range 11-48). Of the 76 patients, 47 (62%) had five or more circulating tumor cells, with a median overall survival of 12.0 months compared with 26.0 months for patients with fewer than five circulating tumor cells (P < 0.001). Circulating tumor cells were detected in 36 of 39 (92%) patients with tumor-related methylated DNA but only 11 of 37 (30%) patients without methylated DNA (P < 0.001). Thirty-nine (51%) patients had one or more methylated marker. Their median overall survival time was 12.0 months compared with 48.0 months or more for patients without methylated DNA (P < 0.001). Prostate-specific antigen-doubling time, circulating tumor cells and methylated DNA were independent predictors of overall survival time.

CONCLUSIONS

Hormone refractory prostate cancer patients with circulating tumor cells and/or tumor-related methylated DNA show a significantly poorer outcome than those without these blood markers.

Predictors of clinical metastasis in prostate cancer patients receiving androgen deprivation therapy: results from CaPSURE

BACKGROUND

Virtually all patients with prostate cancer who receive androgen deprivation therapy (ADT) will ultimately develop evidence of resistance to treatment. The prognosis for patients who develop metastatic castrate-resistant disease is reported to be poor, with overall survival historically estimated to be 24 to 36 months. The goal of the current study was to identify predictors of clinical disease progression in patients with prostate cancer who were receiving ADT.

METHODS

Of the 13,740 men with biopsy-proven prostate cancer who were enrolled in the Cancer of the Prostate Strategic Urological Research Endeavor (CaPSURE) database from 1995 to 2007, 4003 men treated with ADT after diagnosis without evidence of metastases at treatment initiation were identified. The primary endpoint was the development of bone metastasis. Clinical and pathologic characteristics were compared between patients who developed metastasis and those who did not using chi-square tests in a Cox proportional hazards regression model.

RESULTS

The mean age of the men in the cohort was 70 years (range, 39-94 years). One hundred ninety-one men (4.8%) progressed to metastatic disease at a median of 18 months from the initiation of ADT (range, 1-139 months). On multivariate analyses, risk category (hazards ratio [HR], 2.58; P < .0001), percent of biopsies positive >33% (HR, 3.36; P = .003), age </=65 years at diagnosis (HR, 2.11; P = .001, and prostate-specific antigen velocity on ADT (HR, 1.04; P < .001) were found to be significantly associated with the development of metastatic disease after ADT.

CONCLUSIONS

Younger men with high-risk disease appear to have worse prognosis than older men with similar disease. This, along with the other prognostic variables established in the current study, may help identify candidates for clinical trials evaluating secondary treatments for patients with castrate-resistant disease.

Issues in applying multi-arm multi-stage methodology to a clinical trial in prostate cancer: the MRC STAMPEDE trial

Background

The multi-arm multi-stage (MAMS) trial is a new paradigm for conducting randomised controlled trials that allows the simultaneous assessment of a number of research treatments against a single control arm. MAMS trials provide earlier answers and are potentially more cost-effective than a series of traditionally designed trials. Prostate cancer is the most common tumour in men and there is a need to improve outcomes for men with hormone-sensitive, advanced disease as quickly as possible. The MAMS design will potentially facilitate evaluation and testing of new therapies in this and other diseases.

Methods

STAMPEDE is an open-label, 5-stage, 6-arm randomised controlled trial using MAMS methodology for men with prostate cancer. It is the first trial of this design to use multiple arms and stages synchronously.

Results

The practical and statistical issues faced by STAMPEDE in implementing MAMS methodology are discussed and contrasted with those for traditional trials. These issues include the choice of intermediate and final outcome measures, sample size calculations and the impact of varying the assumptions, the process for moving between trial stages, stopping accrual to each trial arm and overall, and issues around perceived trial complexity.

Conclusion

It is possible to use the MAMS design to initiate and undertake large scale cancer trials. The results from STAMPEDE will not be known for some years but the lessons learned from running a MAMS trial are shared in the hope that other researchers will use this exciting and efficient method to perform further randomised controlled trials.

Trial registration

ISRCTN78818544, NCT00268476

[Chemotherapy of hormonorefractory and hormonoresistant metastatic prostate cancer]

Since 2004 and the first improvement in overall survival in hormone refractory prostate cancer patients (HRPC) brought about by docetaxel, numerous phase II and III studies have been initiated. Considering the lack of efficacy in terms of overall survival, hormonal manipulations such as antiandrogen withdrawal, di-ethylstilbesterol or dexamethason are only indicated in "rising PSA" patients without clinical or radiological evidence of metastases. As first line treatment, the optimal chemotherapy regimen is docetaxel (75 mg/m(2) every 3 weeks) in association with prednisone (5 mg twice daily). Second line chemotherapies (mitoxantron, ixabepilon, docetaxel as a re-treatment, vinorelbin, doxorubicin...) provide modest results only in terms of progression-free survival. A phase III study of Straplatin has been prematurely interrupted. Targeted anti-angiogenic therapies have shown encouraging results in patients with metastatic localizations, and underline the need to identify target patients early through cellular markers (mTOR or EGFR overexpression) as well as the uselessness of PSA dosage to monitor efficacy. An ongoing phase III study is evaluating bevacizumab in association with docetaxel to improve overall survival. Both the Provenge vaccine and DN 101 (calcitriol) showed a survival gain of a few months in phase III studies. An ongoing EORTC phase II trial is evaluating antisense oligonucleotids in HRPC. Early introduction of docetaxel raises the issue of when to start chemotherapy as it may be relevant to initiate this treatment before the onset of hormone independence. GETUG 15 trial will try to answer this question.

Prognostic significance of circulating tumor cells in patients with hormone refractory prostate cancer

PURPOSE

Using the CellSearch System we evaluated whether circulating tumor cells predict survival in patients with hormone refractory prostate cancer.

MATERIALS AND METHODS

Circulating tumor cells were counted with the CellSearch System in whole blood. This system was developed using epithelial cell adhesion prostate cancer antibody based, immunomagnetic capture and automated staining methodology. Blood samples from 64 patients with hormone refractory prostate cancer were analyzed.

RESULTS

A threshold of 5 or more circulating tumor cells per 7.5 ml blood was used to evaluate the ability of circulating tumor cells to predict survival. Patient charts were retrospectively examined to determine median overall survival, which was 4 to 27 months (mean +/- SD 14.3 +/- 4.2, median 12.1). Of the 64 patients 32 (50%) had 5 or more circulating tumor cells with a median overall survival of 13.0 months compared with 20.0 months in patients with fewer than 5 (p <0.001). Circulating tumor cells and prostate specific antigen doubling time were significant parameters predicting overall survival on univariate and multivariate analyses. Overall survival in cases that converted from increased to nonincreased circulating tumor cell levels was longer than in cases that converted from nonincreased to increased levels after initiating the circulating tumor cell assay (p = 0.026).

CONCLUSIONS

In this study 5 or more circulating tumor cells in 7.5 ml blood was associated with survival in patients with hormone refractory prostate cancer. Circulating tumor cells may be an independent predictor of overall survival in patients with hormone refractory prostate cancer but they may also complement prostate specific antigen.

Rising prostate-specific antigen after primary treatment of prostate cancer: sequential hormone manipulation

OBJECTIVE

To evaluate systematically the current endocrine treatment options for patients with biochemical recurrence after radical prostatectomy or radiation therapy for localized prostate cancer.

METHODS

Literature search of PubMed documented publications and abstracts from international meetings. Key items included timing and type of salvage hormone therapy, length of its application and handling of side effects.

RESULTS

The majority of patients with isolated prostate-specific antigen (PSA) relapse are not candidates for salvage treatment with curative intent. The PSA threshold that triggers initiation of hormonal therapy is debatable and should be based also on pretreatment risk assessment. Intermittent androgen suppression is an emerging concept to circumvent the unresolved controversy of early versus deferred endocrine therapy. Since the tumor load at time of recurrence is low, peripheral androgen blockade with an antiandrogen and a 5alpha-reductase inhibitor is an acceptable first choice. In case of progression, addition of a LHRH analogue would be the next step. Antiandrogen withdrawal and second-line antiandrogens are clinically of limited value.

CONCLUSIONS

Biochemical-only progression after definitive treatment in curative intent is different from objective or even symptomatic relapse and allows for sequential hormonal therapy with a variety of compounds.

Distinct Prognostic Role of Prostate-Specific Antigen Doubling Time and Velocity at Emergence of Androgen Independence in Patients Treated with Chemotherapy

OBJECTIVES

To investigate whether the prostate-specific antigen doubling time (PSADT) and velocity (PSAV) at the emergence of androgen-independent prostate cancer (AIPC) provide independent prognostic information.

METHODS

Patients treated with chemotherapy were identified in an institutional prostate cancer database. The PSADT was calculated using PSA values from the first increase greater than the PSA nadir during androgen deprivation therapy until the start of the next treatment. The PSAV was calculated using the same PSA values over time. The association with overall survival (OS) from the date of AIPC was analyzed using the Cox proportional hazards regression model.

RESULTS

PSADT and PSAV at the emergence of AIPC were calculated in 91 patients. On univariate analysis, a shorter PSADT and greater PSAV were associated with decreased OS. On multivariate analysis, a PSADT of 12 weeks or less (hazard ratio 3.2), PSAV greater than 10 ng/mL/yr (hazard ratio 2.8), PSA nadir greater than 0.2 with ADT, low hemoglobin, and type of chemotherapy persisted as significant predictors of decreased OS (each P <0.01). A rapid PSADT (12 weeks or less) and high PSAV (greater than 10 ng/mL/yr) predicted for the worst prognosis (25 months median OS, unadjusted). A slow PSADT (greater than 12 weeks), and low PSAV (10 ng/mL/yr or less) predicted for the best prognosis (75 months); other combinations had intermediate prognoses (49 and 50 months).

CONCLUSIONS

The PSAV at the start of AIPC contributes prognostic information independent of the PSADT in patients receiving chemotherapy. Future studies should investigate the relative contribution of each of these factors in predicting survival.

Significance of prostate-specific antigen-doubling time on survival of patients with hormone refractory prostate cancer and bone metastasis: analysis on 56 cases of cancer-specific death

OBJECTIVE

Most of the metastatic diseases initially respond to maximum androgen blockade, but then relapse and lose response, and finally die. After relapse, the disease progresses in various courses. The present study was aimed to establish the predicting factors influencing the survival period of patients at prostate-specific antigen (PSA) relapse (entering the hormone refractory state).

MATERIALS AND METHODS

Fifty-six patients with prostate cancer and bone metastasis, who were treated during the entire disease period at the same hospital and died were studied. To calculate PSA-doubling time, assay of PSA was carried out every 3 months or less.

RESULTS

The period between PSA relapse and death was related with PSA-doubling time at relapse, nadir PSA and the period between the start of treatment and PSA relapse. The PSA-doubling time of 2 months or less at relapse was suggestive of a poor outcome. Final PSA-doubling time was not correlated with the survival period after PSA relapse.

CONCLUSION

The PSA-doubling time at relapse is one of the relevant factors for predicting the survival period after PSA relapse.

Prostate specific antigen doubling time calculation: not as easy as 1, 2, 4

PURPOSE

Although prostate specific antigen doubling time is widely used to predict outcomes such as time to progression and prostate cancer specific mortality, clinicians may be unaware of the impact of method on prostate specific antigen doubling time calculation. We present a critical review of the literature to assess the diversity of methods used to calculate prostate specific antigen doubling time. We then describe the need for methodological consistency with the literature by showing examples from our clinical experience at our institution.

MATERIALS AND METHODS

A comprehensive review of articles evaluating prostate specific antigen doubling time as a prognostic and predictive indicator in various prostate cancer disease states was performed using PubMed. Case examples were drawn from the prostate cancer database at our institution. The database is a registry of 4,651 patients with prostate cancer who have been seen at our institution since 1998.

RESULTS

The methodology of prostate specific antigen doubling time calculation is inconsistent in the literature. Based on our experience and data presented in the literature the different methods in the literature are not always interchangeable. Small deviations from the methods outlined in a study can sometimes lead to wide variation in calculated prostate specific antigen doubling time. This variation of up to several months or longer is large enough to cause errors in assessment of prognosis and can even lead to incorrect management. The rules for prostate specific antigen doubling time calculation found in the literature can be categorized into 4 parameter groups, including method, calculation interval, data acquisition rules and data analysis rules. Case examples illustrate the importance of adherence to the literature with regard to each parameter.

CONCLUSIONS

Consistency with the literature in methodological elements of prostate specific antigen doubling time calculation is essential for the accurate calculation of prostate specific antigen doubling time. Clinicians and researchers should understand how methodological differences influence the value of calculated prostate specific antigen doubling time for purposes of patient care and research.

Cytotoxic chemotherapy for prostate cancer: Who and when?

The survival benefit demonstrated by docetaxel-based therapy in two randomized trials, Southwest Oncology Group (SWOG) 99-16 and TAX 327, has changed the perception of chemotherapy in men with hormone-refractory prostate cancer from nihilism to optimism. These survival improvements are of similar magnitude to those found in trials that established chemotherapeutic regimens for metastatic breast, lung, or colorectal cancer. The timing of chemotherapy in the aforementioned solid tumors is much more clearly defined than in men with metastatic prostate cancer. Traditionally, chemotherapy in men with hormone-resistant prostate cancer was reserved for symptomatic patients only; the inclusion of symptomatic and asymptomatic patients in SWOG 99-16 and TAX 327 has raised several questions regarding the optimal use of chemotherapy in these patients. When is the best time to initiate docetaxel-based chemotherapy? Is it appropriate to use chemotherapy in high-risk patients as adjuvant therapy? Although retrospective analysis of current trials may provide hypothesis, only properly designed randomized clinical trials will answer these questions.

Pre-treatment nomogram for disease-specific survival of patients with chemotherapy-naive androgen independent prostate cancer

OBJECTIVE

Our objective was to develop a nomogram that predicts the probability of cancer-specific survival in men with untreated androgen-independent prostate cancer (AIPC).

METHODS

AIPC was diagnosed in 129 consecutive patients between 1989 and 2002. No patient received cytotoxic chemotherapy. Univariate and multivariate Cox regression models were used to test the association between prostate-specific antigen (PSA) level at initiation of androgen deprivation, PSA doubling time (PSADT), PSA nadir on androgen deprivation therapy (ADT), time from ADT to AIPC, and AIPC-specific mortality. Multivariate regression coefficients were then used to develop a nomogram predicting AIPC-specific survival at 12-60 mo after AIPC diagnosis. Two-hundred bootstrap resamples were used to internally validate the nomogram.

RESULTS

AIPC-specific mortality was recorded in 74 of 129 patients (57.4%). Other-cause mortality was recorded in 7 men (5.4%). Median overall survival was 52.0 mo (mean, 36.0 mo) and median AIPC-specific survival was 54.0 mo (mean, 35.0 mo). In univariate regression models, all variables were significant predictors of AIPC-specific survival (p < or = 0.02). In multivariate models, PSADT and time from androgen deprivation to AIPC remained statistically significant (p < or = 0.004). Bootstrap-corrected predictive accuracy of the nomogram was 80.9% versus 74.9% for our previous model.

CONCLUSIONS

A nomogram predicting AIPC-specific survival is between 13% and 14% more accurate than previous nomograms and 6% more accurate than tree regression-based predictions obtained from the same data. Moreover, a nomogram approach combines several advantages, such as user-friendly interface and precise estimation of individual recurrence probability at several time points after AIPC diagnosis, which all patients deserve to know and all treating physicians need to know.

Critical analysis of prostate-specific antigen doubling time calculation methodology

BACKGROUND

Prostate-specific antigen (PSA) doubling time (PSADT) has emerged as an important surrogate marker of disease progression and survival in men with prostate carcinoma. The literature is replete with different methods for calculating PSADT. The objective of the current study was to identify the method that best described PSA growth over time and predicted disease-specific survival in men with androgen-independent prostate carcinoma.

METHODS

PSADT was calculated for 122 patients with androgen-independent prostate carcinoma using 2 commonly used methods: best-line fit (BLF) and first and last observations (FLO). Then, PSADT was calculated by using both a random coefficient linear (RCL) model and a random coefficient quadratic (RCQ) model. Statistical analysis was used to compare the ability of the methods to fit the patients' PSA profiles and to predict disease-specific survival.

RESULTS

The RCQ model provided the best fit of the patients' PSA profiles, as determined according to the significance of the added parameters for the RCQ equation (P < or = 0.002). The PSADT estimates from the FLO method, the RCL model, and the RCQ model were highly significant predictors (P < 0.001) of disease-specific survival, whereas estimates from the BLF method were not found to be significant predictors (P = 0.66). PSADT estimates from the RCQ and RCL models provided an improved correlation of disease-specific survival (both R(2) = 0.55) compared to the FLO (R(2) = 0.11) and BFL (R(2) = 0.003) methods.

CONCLUSIONS

Random coefficient methods provided a more reliable fit of PSA profiles than other models and were superior to other available models for predicting disease-specific survival in patients with androgen-independent prostate carcinoma. The authors concluded that consideration should be given to applying the RCL or RCQ models in future assessments of PSADT as a predictive parameter.

Chemotherapy for metastatic disease: current status

Chemotherapy now has an established role in the treatment of hormone-refractory metastatic prostate cancer. This review summarises the results of the latest trials and discusses ongoing studies investigating the role of chemotherapy earlier in the disease.

Circulating tumor cells predict survival in patients with metastatic prostate cancer

OBJECTIVES

To determine whether circulating tumor cells (CTCs) predict for survival in patients with metastatic prostate cancer (PCa) and to compare its prognostic abilities with other clinical factors.

METHODS

Blood samples from 37 patients with metastatic PCa were analyzed for CTCs. CTCs were enriched from 7.5 mL blood using magnetic nanoparticles targeting the epithelial cell adhesion molecule and then fluorescently labeled. The samples were analyzed by multiparameter flow cytometry, and events with appropriate light scatter properties that were nucleic acid dye positive, cytokeratin positive, and CD45 negative were defined as CTCs.

RESULTS

The number of CTCs found ranged from 0 to 8586 per 7.5 mL (mean 530 +/- 1887, median 5). A threshold of 5 or more CTCs per 7.5 mL of blood was used to evaluate the ability of CTCs to predict for overall survival. Of the 37 patients, 23 (62%) had 5 or more CTCs, with a median overall survival of 0.70 year compared with more than 4 years for those patients with fewer than 5 CTCs (log-rank P = 0.002, Cox hazards ratio 7.4). In the subset of 26 patients with hormone-refractory PCa, the presence of CTCs was the most significant parameter predictive of survival in univariate and multivariate analyses.

CONCLUSIONS

In this pilot study, the presence of 5 or more CTCs in 7.5 mL blood was associated with poor overall survival in patients with metastatic PCa.

A retrospective study of the time to clinical endpoints for advanced prostate cancer

OBJECTIVE

To determine the natural history of patients with prostate cancer who start initial androgen-deprivation therapy (ADT) for biochemical failure with no radiographic evidence of disease (D0) or with radiographic metastatic disease (D2), as the history is either not well-defined or is changing, and such data are critical for guiding therapy after prostate cancer recurrence.

PATIENTS AND METHODS

We retrospectively assessed the time to androgen-independence (AI), defined as the first sustained rise in prostate-specific antigen (PSA) level on ADT, time to metastatic disease and overall survival for 80 patients with metastatic prostate cancer in clinical trials at the National Cancer Institute.

RESULTS

ADT was initiated after metastatic disease in 37 patients and before metastatic disease in 43 patients; in these 43 patients, the median time to developing metastatic disease on ADT was 37.8 months. The median time to AI from the initiation of ADT was 19.3 and 13.1 months in D0 and D2 patients, respectively. The median overall survival from the start of ADT was 89.0 and 63.0 months, and the median overall survival from the time of AI was 63.1 and 44.2 months in D0 and D2 patients, respectively. These 80 patients, which included 43 who had no metastatic disease when starting ADT, had a median survival of 54.8 months after AI prostate cancer.

CONCLUSIONS

We describe the natural history of AI prostate cancer in D0 patients who eventually developed metastasis, and in D2 patients. The results suggest a longer than expected survival with AI prostate cancer, and to our knowledge this is the first study to report the time to metastatic disease for D0 patients from ADT and from AI. These results can be used to help design clinical trials in patients with D0 prostate cancer.

Present status and perspectives in the treatment of hormone-refractory prostate cancer

The cornerstone in the treatment of de novo or recurrent metastatic prostate cancer is androgen deprivation. Unfortunately, nearly all patients will develop androgen-independent ('hormone-refractory') disease with progressive clinical deterioration and ultimately death. Chemotherapy has been shown to palliate symptoms of hormone-refractory disease but not to improve survival. Recently, two large phase III trials have demonstrated an overall survival advantage for patients treated with docetaxel-based regimens as compared to the best standard of care. Indeed, investigations into the pathophysiology of this malignancy, novel biological agents, skeletal protectants and radiopharmaceuticals are expanding the clinician's armamentarium and improving the patient's outcome.

Prostate-specific antigen nadir and cancer-specific mortality following hormonal therapy for prostate-specific antigen failure

PURPOSE

For men receiving androgen-suppression therapy (AST) for a rising postoperative or postradiation prostate-specific antigen (PSA), we evaluated whether a PSA nadir of more than 0.2 ng/mL was significantly associated with prostate cancer-specific mortality (PCSM).

PATIENTS AND METHODS

The study cohort comprised 747 men with rising PSA and negative bone scan after surgery (n = 486) or radiation therapy (n = 261) who were treated with AST. Cox regression was used to evaluate whether a significant association existed between the PSA nadir level after 8 months of AST and the time to PCSM, controlling for treatment and known prognostic factors.

RESULTS

The post-AST PSA nadir (pCox < .0001), the pre-AST PSA doubling time (DT) (pCox = .002), PSA level (P = .0001), and Gleason eight to 10 cancers (pCox = .01) were significantly associated with time to PCSM. The adjusted hazard ratio for PCSM was 20 (95% CI, 7 to 61; pCox < .0001), for men with a PSA nadir of more than 0.2 ng/mL as compared with all others. A PSA DT of less than 3 months was observed in 30% (224 of 747) of the study cohort. Of the 28 observed prostate cancer deaths, 21 (75%) occurred in men whose PSA nadir was more than 0.2 ng/mL and who had a PSA DT of less than 3 months.

CONCLUSION

A PSA nadir of more than 0.2 ng/mL after 8 months of AST given for postoperative or postradiation PSA failure is significantly associated with PCSM and is clinically significant because it accounted for 75% of the cancer deaths observed in this study.

Antigen-presenting cells 8015 (Provenge) in patients with androgen-dependent, biochemically relapsed prostate cancer

BACKGROUND

Antigen-presenting cells 8015 (APC8015; Provenge) is an immunotherapeutic product designed to initiate a T-cell-mediated immune response against prostatic acid phosphatase, an antigen overexpressed in 95% of prostate cancer cells. In phase I/II trials, APC8015 has shown immunologic and clinical responses in patients with androgen-independent prostate cancer. This phase II trial was conducted to assess the prostate-specific antigen (PSA)-modulating effects of APC8015 in patients with androgen-dependent prostate cancer (ADPC) with biochemical progression.

PATIENTS AND METHODS

Patients with nonmetastatic recurrent disease as manifested by increasing PSA levels (0.4-6.0 ng/mL) and who had undergone previous definitive surgical or radiation therapy were enrolled. Therapy consisted of APC8015 infusion on weeks 0, 2, and 4 (ie, 3 infusions). Prostate-specific antigen was measured at baseline and monthly until disease progression, defined as a doubling of the baseline or nadir PSA value (whichever was lower) to > or = 4 ng/mL or development of distant metastases.

RESULTS

Thirteen of 18 patients demonstrated an increase in PSA doubling time (PSADT), with a median increase of 62% (4.9 months before treatment vs. 7.9 months after treatment; P = 0.09; signed-rank test).

CONCLUSION

Therapy was well tolerated. APC8015 as single-agent immunotherapy for patients with ADPC and biochemical progression did not result in > or = 50% decrease in PSA from baseline levels but did appear to modulate PSADT in some patients. Further manipulations of host immunity may be required to achieve a significant antitumor effect.

An interdisciplinary approach to treating prostate cancer

Urologists often are faced with challenges in treating men with metastatic prostate cancer. Although historically chemotherapy has had limited utility in treating this disease, therapeutic nihilism surrounding its use is no longer warranted, as demonstrated by results of 2 recent randomized clinical trials showing that docetaxel-based chemotherapy improves survival in patients with hormone-refractory prostate cancer (HRPC). Although the survival benefit was a modest 2 months, the results hold the promise that docetaxel-based treatment in earlier-stage disease may provide a longer survival advantage. The Cancer and Leukemia Group B (CALGB) 90203 and TAX 3501 studies are phase 3 neoadjuvant and adjuvant radical prostatectomy trials designed to assess the role of docetaxel in patients with high-risk localized disease. These 2 trials, along with the Southwest Oncology Group (SWOG) 9921 trial, which will assess the potential for adjuvant mitoxantrone, are paving the way for earlier systemic treatment. The need for better therapies for patients routinely seen in the urology clinic and the potential for improvements with chemotherapy necessitate an increasing collaboration between urologists and oncologists. Referral to a medical oncologist for a full discussion of treatment options is in the best interest of patients with HRPC, and patients at high-risk for treatment failure should be encouraged to consider clinical trial enrollment.

Prostate cancer relapse after therapy with curative intention: a diagnostic and therapeutic dilemma

Prostate cancer is the most common malignant disease and second in causes of cancer death among men in Western Europe and North America. Despite improved surgical and irradiation techniques tumor relapse after curatively intended therapy is not uncommon. Due to the difficulty in discriminating local and systemic progression, it is often difficult to decide what this means for the patient and what kind of second-line treatment has to be given. Modern imaging techniques (MRI with endorectal coil, Choline-PET-CT, ProstaScint-Scan) are used for diagnosis of prostate cancer relapse. Nevertheless, early detection of local tumor relapse and likewise the detection of disseminated tumor cells often fails. To differentiate between local and systemic progression, prognostic factors of the primary tumor (grading, surgical margins, infiltration of the seminal vesicles, lymph node metastases) and PSA kinetics are used. The time from initial treatment to biochemical relapse and PSA doubling time are of highest prognostic relevance. Local progression allows second-line local treatment with potentially curative results (local irradiation after radical prostatectomy, salvage-surgery / cryotherapy / HIFU after irradiation), while in the case of systemic progress a palliative systemic therapy (hormonal treatment, chemotherapy, bisphosphonates) is indicated. Before deciding on the most appropriate therapy, prognostic factors and the patient's individual situation (co-morbidity, life expectancy, individual wishes) should be taken into account.

Multidisciplinary management of advanced prostate cancer: Changing perspectives on referring patients and enhancing collaboration between oncologists and urologists in clinical trials

Prostate cancer traditionally was managed by monotherapy, and treatment was almost exclusively provided by the urologic surgeon. As ongoing clinical trials in advanced disease identify novel agents or combination therapies with good tolerability and potential survival benefits, multidisciplinary management may offer optimal care for men with high-risk prostate cancer, as it does for women with breast cancer. Patients with high-risk recurrent or metastatic disease should be informed of clinical trials for which they may be eligible.