Prostate-specific antigen and other markers of therapeutic response

Prostate-specific antigen half-life: a new predictor of progression-free survival and overall survival in Chinese prostate cancer patients

We investigated the potential value of prostate-specific antigen half-life (PSAHL) and decreasing velocity (PSAVd) to predict progression-free survival (PFS) and overall survival (OS) in Chinese patients with prostate cancer. A total of 153 patients treated with hormonal therapy were included in the study. Of these, 78 patients progressed to hormone-refractory prostate cancer (HRPC) and 24 patients died by the end of follow-up. PSAHL was defined as the time during which prostate-specific antigen (PSA) concentration became half of the initial value during the first hormonal therapy. PSAVd reflected the decreasing velocity of PSA during the first hormonal therapy. PFS was defined as the interval from the beginning of hormonal therapy to HRPC. Cox proportional hazards regression analysis was used to evaluate whether PSAHL and PSAVd were significantly associated with PFS and OS. The median PSAHL and PSAVd were 0.50 months and 33.8 ng mL(-1) per month. The median PFS and OS were 22.7 months (95% confidence interval [CI], 22.0-29.6 months) and 43.5 months (95% CI, 37.9-48.4 months), respectively. On univariate and multivariate analysis, long PSAHL (> 0.5 months), metastatic disease, high biopsy Gleason scores (>or= 8) and high nadir PSA (> 0.4 ng mL(-1)) were all found to be significantly associated with short PFS. Long PSAHL, high nadir PSA and short PSA doubling time (PSADT Collapse

Key Words

• predictor
• prognosis
• prostate cancer
• prostate-specific antigen decreasing velocity
• prostate-specific antigen half-life

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MESH Headings

• Adult
• Aged
• Aged, 80 and over
• China
• Disease Progression
• Half-Life
• Humans
• Male
• Middle Aged
• Proportional Hazards Models
• Prostate-Specific Antigen/blood
• Prostatic Neoplasms/blood
• Prostatic Neoplasms/immunology
• Prostatic Neoplasms/pathology
• Survival Analysis

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Affiliation(s)

Guo-Wen Lin Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Xu-Dong Yao Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Shi-Lin Zhang Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Bo Dai Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Chun-Guang Ma Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Hai-Liang Zhang Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Yi-Jun Shen Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Yao Zhu Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Yi-Ping Zhu Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Guo-Hai Shi Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Xiao-Jian Qin Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China
Ding-Wei Ye Department of Urology, Cancer Hospital, Fudan University, Shanghai 200032, China Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China

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Serum PSA half-life as a predictor of survival for hormone-refractory prostate cancer patients: modelization using a standardized set of response criteria

OBJECTIVE

Changes of serum prostate-specific antigen (PSA) during chemotherapy have been validated as a marker of response for hormone-refractory prostate cancer (HRPC) patients. We retrospectively established new response criteria to assess the risk of death.

METHODS

Two hundred fifty-six chemonaive HRPC patients treated with chemotherapy were included in the analysis. According to PSA half-life (HL) dynamics, three response categories were defined: responders (R), late-progressors (LP) and initial-progressors (IP), that were compared with Working Group (WG) criteria. PSA HL time to failure (TTF) and overall survival (OS) were estimated and compared between HT categories. Multivariate regression analysis was performed to isolate the impact on OS of these response categories. A new predictor of survival, delta-time PSA interval (DeltaT) was described.

RESULTS

PSA HL categories were strongly related with WG criteria (P = 0.0001). PSA HL TTF differed among PSA HL categories: 4.2, 2.3, and 0.9 months for R, LP, and IP patients, respectively, and their respective median OS were 27, 19.7, and 12.3 months (P = 0.0001). For DeltaT > or = 3 versus <3 months, median OS significantly differed: 24.9 months versus 13.2 months (P = 0.0001).

CONCLUSIONS

PSA HL dynamics during chemotherapy were able to accurately predict survival, earlier than WG-defined progression criteria. This criterion should be prospectively evaluated in randomized trials for HRPC patients in order to better estimate the risk of death.

Is there a role for platinum chemotherapy in the treatment of patients with hormone-refractory prostate cancer?

Docetaxel chemotherapy is the current standard of care for metastatic hormone-refractory prostate cancer (HRPC). Platinum chemotherapy drugs, such as cisplatin and carboplatin, have moderate single-agent activity in HRPC. Next-generation platinum drugs, including satraplatin and oxaliplatin, may have additional activity in the management of HRPC. Furthermore, neuroendocrine differentiation may play a role in disease progression, providing a rationale for platinum-based chemotherapy in the management of HRPC. The authors reviewed the MEDLINE database for reports related to platinum-based chemotherapy in patients with advanced prostate cancer and evaluated studies that reviewed the role of neuroendocrine differentiation in the progression of HRPC. Older studies from the 1970s and 1980s suggested a lack of activity of cisplatin and carboplatin; however, those studies were flawed at least in part by their methods of response assessment. More recent Phase II studies of carboplatin suggested a moderate level of clinical and palliative activity when it was used as a single agent. However, when carboplatin was combined with a taxane and estramustine, high response rates were observed in several recent clinical trials. In addition, a randomized trial suggested that satraplatin plus prednisone improved progression-free survival compared with prednisone alone. For patients who progressed after docetaxel, no standard options existed in the literature that was reviewed. Several preliminary reports suggested that carboplatin and oxaliplatin may have activity as second-line chemotherapy. Platinum chemotherapy drugs historically have been considered inactive in HRPC, although a review of the data suggested otherwise. Carboplatin, in particular, induced very high response rates when it was combined with estramustine and a taxane, but it also appeared to have activity in patients who progressed after docetaxel. Satraplatin plus prednisone is being investigated in a large Phase III trial as second-line chemotherapy for HRPC. Targeting neuroendocrine cells may provide a new therapeutic approach to HRPC.

Magnetic resonance imaging of the axial skeleton enables objective measurement of tumor response on prostate cancer bone metastases

BACKGROUND

There is currently no technique to image quantitatively bone metastases. Here, we assessed the value of MRI of the axial skeleton (AS-MRI) as a single step technique to quantify bone metastases and measure tumor response.

METHODS

AS-MRI was performed in 38 patients before receiving chemotherapy for metastatic HRPCa, in addition to PSA, computed tomography of the thorax, abdomen, and pelvis [CT-TAP]; and Tc-99m bone scintigraphy. A second AS-MRI was performed in 20 patients who completed 6 months of chemotherapy. Evaluation of tumor response was performed using RECIST.

RESULTS

Only 11 patients (29%) had RECIST measurable metastases in soft-tissues or lymph nodes on baseline CT-TAP. AS-MRI identified a diffuse infiltration of the bone marrow in 8 patients and focal measurable metastatic lesions in 25 patients (65%), therefore, doubling the proportion of patients with measurable lesions. Transposing RECIST on AS-MRI in 20 patients who completed 6 months of treatment, allows the accurate estimation of complete response (n = 2), partial response (n = 2), stable disease (n = 5), or tumor progression (n = 11), as it is done using CT-TAP in soft tissue solid metastases.

CONCLUSIONS

MRI of axial skeleton enables precise measurement and follow-up of bone metastases as it is for other soft-tissue metastasis.

Time and PSA threshold model prognosticates long-term overall and disease-specific survival in prostate cancer patients as early as 3 months after external beam radiation therapy

The specific aim of this analysis was to evaluate the capability of a time and prostate-specific antigen (PSA) threshold model to prognosticate overall survival (OS) and disease-specific survival (DSS) based on early PSA kinetics after radiotherapy for prostate cancer by retrospective review of outcomes in 918 patients. Crossing below analyzed PSA thresholds at specific defined time points reduced disease-specific death hazard ratios to relative to the cohort above threshold. The time and PSA threshold model demonstrates the ability to prognosticate OS and DSS as early as 3 months post-radiotherapy for prostate cancer.

Early prostate-specific antigen (PSA) kinetics following prostate carcinoma radiotherapy

BACKGROUND

The goal of the current study was to analyze the prognostic value of early prostate-specific antigen (PSA) kinetics, with PSA assessed as reaching or failing to reach discrete threshold values at fixed time points during follow-up after external-beam radiotherapy (EBRT) for prostate carcinoma.

METHODS

The authors conducted a retrospective review of PSA follow-up for 839 patients treated between May 1987 and December 2000 at the Cleveland Clinic Foundation (Cleveland, OH). They also assessed the impact on bRFS of PSA levels lower than defined threshold values at given time points during follow-up.

RESULTS

During a median follow-up of 74 months (range, 24-189 months), 540 patients (64.4%) maintained bRFS, whereas 299 patients (35.6%) did not maintain bRFS. The median nadir among patients with sustained bRFS was 0.4 ng/mL, with a median time to nadir of 28.9 months. Patients who did not maintain bRFS reached a median nadir of 1.3 ng/mL at a median of 15 months (P < 0.0001 for both nadir level and time to nadir). Reaching PSA thresholds of 3.0, 2.0, 1.0, 0.5, and 0.2 ng/mL at any time during follow-up was correlated with improved bRFS (P < 0.0001, each threshold). Patients whose PSA levels crossed the appropriate thresholds within 3 and 6 months of follow-up, irrespective of the time or level of eventual nadir, exhibited significantly improved bRFS when compared with patients whose PSA levels reached those thresholds at any time during follow-up and patients whose PSA levels never reached those thresholds (all thresholds: P < 0.0001).

CONCLUSIONS

Despite previous conclusions that early PSA assessment may lack prognostic value, the data obtained in the current study suggest that the kinetics of early PSA decline is predictive of long-term bRFS when assessed using a time-and-PSA threshold model. After EBRT for prostate carcinoma, PSA levels below various discrete PSA thresholds were indicative of statistically meaningful long-term outcome differences between experimental arms as early as 90 days after radiotherapy. If the time-and-PSA threshold model is shown to be predictive of prostate carcinoma mortality as well, then it may allow the scientific community to evaluate promising treatment concepts and technologies at a highly accelerated pace.

Recent advances in chemotherapy for advanced prostate cancer

Recently, several important studies have validated prostate-specific antigen (PSA) as a reliable measure of response to chemotherapeutic treatment in advanced hormone-refractory prostate cancer. Furthermore, although chemotherapy in this setting has always been considered palliative, several analyses of recent clinical trials have demonstrated a significant association between declines in PSA values of 50% or more and prolonged survival. Mitoxantrone, in combination with prednisone, has been shown to provide significant palliation and improved quality of life. The use of combinations of chemotheraputic agents also seems to provide significantly superior objective and subjective responses compared with single-agent regimens. In particular, estramustine has been shown to synergize many of the agents used in prostate cancer treatment and has been demonstrated to provide significant palliation and decline in PSA levels in combination with vinblastine, vinorelbine, etoposide, paclitaxel, and docetaxel. The results of several important trials of the taxanes both as single agents and in combination with estramustine have been completed in the past year and have demonstrated that these agents are very effective in the treatment of hormone-refractory prostate cancer.