Biomedical subjects

Ming-Hui Chen

Publications and source records attributed to Ming-Hui Chen.

9 recordsLinked to original sources

PubMed2003

Advanced age at diagnosis is an independent predictor of time to death from prostate carcinoma for patients undergoing external beam radiation therapy for clinically localized prostate carcinoma.

BACKGROUND: Whether age at diagnosis is predictive of time to prostate carcinoma specific death after external beam radiation therapy (RT) for patients who are diagnosed with clinically localized prostate carcinoma during the prostate specific antigen (PSA) era has not been investigated previously. METHODS: A multivariate Cox regression analysis was used to evaluate the ability of pretreatment risk group and age at diagnosis to predict time to all causes of death and time to death from prostate carcinoma for 381 patients who underwent RT for clinically localized prostate carcinoma. RESULTS: Age at diagnosis, as a continuous variable (P(continuous) = 0.04), and risk group (P(categorical) = 0.02) were independent predictors of time to death from prostate carcinoma, whereas only age at diagnosis (P(continuous) = 0.01) was a predictor of time to all causes of death. When analyzed as a categorical variable, beginning at age 73 years, age at diagnosis was an independent predictor (P(categorical) < 0.04) of time to death from prostate carcinoma. Upon further analysis, this finding was limited to high-risk patients. For example, age > or = 75 years at diagnosis predicted for a shorter median time to death from prostate carcinoma (6.3 years vs. 9.7 years; P = 0.002) in high-risk patients. CONCLUSIONS: Patients with clinically localized, high-risk prostate carcinoma who were diagnosed at age > or = 73 years and were treated with RT had a worse prognosis compared with patients who were diagnosed age < 73 years, raising the possibility that a more aggressive prostate carcinoma biology may develop during andropause.

Age Factors↗

PubMed2002

Changing prostate-specific antigen outcome after surgery or radiotherapy for localized prostate cancer during the prostate-specific antigen era.

PURPOSE: To evaluate the change in prostate-specific antigen (PSA) outcome after radical prostatectomy (RP) or external beam radiotherapy (EBRT), controlling for follow-up during the PSA era. METHODS AND MATERIALS: The study cohort consisted of 1440 patients with clinically localized prostate cancer managed with RP (n = 1059) or EBRT (n = 381) between 1989 and 2000. A single genitourinary pathologist reviewed all pathology specimens. For patients with a 2-year minimal follow-up, the 2-year actual PSA outcome stratified by risk group (low vs. high) was calculated for three periods (January 1, 1989 to December 31, 1992; January 1, 1993 to December 31, 1996; and January 1, 1997 to December 31, 2000) and compared for each treatment modality. PSA failure was defined using the American Society for Therapeutic Radiology and Oncology consensus definition for all patients, and comparisons were made using a chi-square metric. RESULTS: During the study period, the proportion of patients treated with RP and EBRT with low-risk disease increased significantly (p <0.0001) from 60% to 89% and from 26% to 76%, respectively. In addition, the 2-year actual PSA outcome also improved from 60% to 82% (RP: p < 0.0001) and from 67% to 91% (RT: p = 0.0008). The 2-year actual PSA outcome was not significantly different in the low-risk patients but improved during the three periods in the high-risk patients treated with RP (from 20% to 39% to 75%, p = 0.0004) or EBRT (from 50% to 59% to 83%, p = 0.01). This improvement in PSA outcome could be explained by a shift toward a more favorable PSA level (RP: p = 0.0002; RT: p = 0.006) and clinical T stage (RP: p = 0.0008, RT: p < 0.0001) distribution for patients with biopsy Gleason score >or=7 disease. CONCLUSION: Improved PSA outcome during the PSA era after RP or EBRT has resulted from a shift in presentation toward low-risk disease and earlier detection of high-grade disease.

Aged↗

PubMed2002

Biochemical outcome after radical prostatectomy or external beam radiation therapy for patients with clinically localized prostate carcinoma in the prostate specific antigen era.

BACKGROUND: To the authors' knowledge, consensus is lacking regarding the relative long-term efficacy of radical prostatectomy (RP) versus conventional-dose external beam radiation therapy (RT) in the treatment of patients with clinically localized prostate carcinoma. METHODS: A retrospective cohort study of 2635 men treated with RP (n = 2254) or conventional-dose RT (n = 381) between 1988-2000 was performed. The primary endpoint was prostate specific antigen (PSA) survival stratified by treatment received and high-risk, intermediate-risk, or low-risk group based on the serum PSA level, biopsy Gleason score, 1992 American Joint Commission on Cancer clinical tumor category, and percent positive prostate biopsies. RESULTS: Estimates of 8-year PSA survival (95% confidence interval [95% CI]) for low-risk patients (T1c,T2a, a PSA level < or = 10 ng/mL, and a Gleason score < or = 6) were 88% (95% CI, 85, 90) versus 78% (95% CI, 72, 83) for RP versus patients treated with RT, respectively. Eight-year estimates of PSA survival also favored RP for intermediate-risk patients (T2b or Gleason score 7 or a PSA level > 10 and < or = 20 ng/mL) with < 34% positive prostate biopsies, being 79% (95% CI, 73, 85) versus 65% (95% CI, 58, 72), respectively. Estimates of PSA survival in high-risk (T2c or PSA level > 20 ng/mL or Gleason score > or = 8) and intermediate-risk patients with at least 34% positive prostate biopsies initially favored RT, but were not significantly different after 8 years. CONCLUSIONS: Intermediate-risk and low-risk patients with a low biopsy tumor volume who were treated with RP appeared to fare significantly better compared with patients who were treated using conventional-dose RT. Intermediate-risk and high-risk patients with a high biopsy tumor volume who were treated with RP or RT had long-term estimates of PSA survival that were not found to be significantly different.

Carcinoma↗

PubMed2002

Initial decline in hemoglobin during neoadjuvant hormonal therapy predicts for early prostate specific antigen failure following radiation and hormonal therapy for patients with intermediate and high-risk prostate cancer.

BACKGROUND: Declines in serum hemoglobin (Hgb) levels occur from the use of androgen suppression therapy (AST) in the treatment of prostate cancer patients. We studied whether time to prostate specific antigen (PSA) failure following external beam radiation therapy (RT) and AST could be predicted by the rate of decline in the Hgb level following the administration of neoadjuvant AST or by the Hgb level at presentation or at the start of RT. METHODS: The study cohort comprised 110 intermediate or high-risk prostate cancer patients who were managed using three-dimensional conformal RT (70 Gy) and 6 months of AST (2 months neoadjuvant, concurrent, and adjuvant). A Cox regression multivariable analysis was performed to evaluate the ability of the rate of decline of the Hgb from baseline to the start of RT, baseline PSA level, Gleason score, percent positive biopsies, and T-category to predict time to PSA failure. RESULTS: A decline in the Hgb level of 1 g/dL or more during the first month of AST was the only significant predictor of time to PSA failure (P = 0.02) on multivariable analysis. The relative risk of PSA failure (95% confidence interval) for patients with a decline in Hgb level during the first month (> or = 1 g/dL vs. < 1 g/dL) was 6.3 (2.4, 8.3) and the 3-year estimate of PSA outcome was 66% versus 82% (P = 0.04), respectively. There were no imbalances in the pretreatment prognostic factors or length of follow-up in each of these groups. CONCLUSION: A decline of 1 g/dL or more in Hgb level during the first month of neoadjuvant AST was a predictor of early PSA failure following RT and AST in intermediate and high-risk prostate cancer patients.

Aged↗

PubMed2002

Lower prostate specific antigen outcome than expected following radical prostatectomy in patients with high grade prostate and a prostatic specific antigen level of 4 ng/ml. Or less.

PURPOSE: We report the estimates of 10-year prostate specific antigen (PSA) outcome following radical prostatectomy in patients with or without grade 4 or 5 disease in the needle biopsy or prostatectomy specimen stratified by the presenting PSA level. MATERIALS AND METHODS: From 1989 to 2001, 2,254 patients treated with radical prostatectomy for clinically localized prostate cancer comprised the study cohort. PSA outcome was estimated using the actuarial method of Kaplan and Meier, and was stratified by the presenting PSA level and needle biopsy and prostatectomy Gleason score. RESULTS: The 10-year estimates of PSA outcome declined significantly (p </=0.002) for patients with biopsy or prostatectomy Gleason score 6 or less as the presenting PSA level increased. This trend was observed for biopsy and prostatectomy Gleason score 7 or higher except for the PSA 4 or less group which did significantly worse (46% versus 62%, p = 0.03) compared to the PSA greater than 4 to 10 ng./ml. group. This finding may be explained by a low serum free testosterone level and the presence of a significantly higher proportion of prostatectomy Gleason score 8 to 10 disease (25% versus 16%, p = 0.03) in the PSA 4 or less versus greater than 4 to 10 ng./ml. group. CONCLUSIONS: Patients with Gleason grade 4 or 5 disease in the radical prostatectomy specimen and a presenting PSA of 4 ng./ml. or less may be androgen deficient and have a significantly lower estimate of 10-year PSA outcome then expected based on the presenting PSA level.

Adult↗

PubMed2002

Percentage of core lengths involved with prostate cancer: does it add to the percentage of positive prostate biopsies in predicting postoperative prostate-specific antigen outcome for men with intermediate-risk prostate cancer?

OBJECTIVES: To evaluate whether the percentage of core lengths involved with prostate cancer added clinically significant information concerning the time to postoperative prostate-specific antigen (PSA) failure in the intermediate-risk patient beyond what is provided by the percentage of positive biopsies. METHODS: Cox regression multivariable analysis was performed to compare the ability of the two measurements of biopsy cancer volume to predict the time to PSA failure from a series of 184 surgically treated intermediate-risk patients. PSA outcome was estimated using the actuarial method of Kaplan and Meier, and comparisons were made using the log-rank test. RESULTS: Both the percentage of core lengths involved with prostate cancer (P = 0.01) and the percentage of positive biopsies (P = 0.002) were significant predictors of the time to PSA failure on univariable analysis. The 4-year PSA outcome was 83% versus 47% (P = 0.0008) and 83% versus 53% (P = 0.007) for the percentage of positive biopsies stratified by 50% or less versus greater than 50% and the percentage of core lengths involved with prostate cancer stratified by 25% or less versus greater than 25%, respectively. However, only the percentage of positive biopsies remained significant (P = 0.03) on multivariable analysis. CONCLUSIONS: The percentage of core lengths involved with prostate cancer did not provide additional clinically relevant information to the percentage of positive biopsies for patients with intermediate-risk prostate cancer. Therefore, the routine measurement of core involvement may not be necessary in this patient population.

Analysis of Variance↗

PubMed2002

Predictive factor analysis as the basis for the clinical utility of percent positive prostate biopsies in patients with intermediate-risk prostate cancer.

OBJECTIVES: To define the clinical reason for the further refinement of stratification of prostate-specific antigen (PSA) outcome using percent positive prostate biopsies in intermediate-risk patients. METHODS: A chi-square metric was used to compare the distribution of pretreatment clinical and post-treatment pathologic factors for patients with intermediate-risk prostate cancer with 50% or less versus greater than 50% positive prostate biopsies. The PSA outcome stratified by the percent positive biopsies was calculated according to the Kaplan-Meier actuarial method. Comparisons of actuarial PSA failure-free survival were performed using the log-rank test. RESULTS: The group with greater than 50% positive biopsies for prostate cancer had a significantly higher proportion of patients with pretreatment PSA values greater than 10 to 20 ng/mL (P = 0.01), biopsy Gleason score 4+3 (P = 0.05), and 1992 American Joint Committee on Cancer clinical category T2b (P = 0.01) than did the group with less than 50% positive biopsies. The group with greater than 50% positive biopsies also had a significantly higher proportion of patients with prostatectomy Gleason score 4+3 or higher (P = 0.001), pathologic Stage T3b (P <0.0001), and rate of positive surgical margins (P = 0.002) than did the group of patients with less than 50% positive biopsies. CONCLUSIONS: The results of this study provide an explanation on the basis of the pretreatment and post-treatment predictive factors for the difference in PSA outcome for intermediate-risk patients when stratified by the percent positive biopsies.

Biopsy↗

PubMed2002

Evolution of the presentation and pathologic and biochemical outcomes after radical prostatectomy for patients with clinically localized prostate cancer diagnosed during the PSA era.

OBJECTIVES: To demonstrate the evolution of the clinical presentation and pathologic and biochemical outcomes for patients with clinically localized prostate cancer treated with radical prostatectomy during the prostate-specific antigen (PSA) era. METHODS: One thousand fifty-nine consecutive men treated with radical prostatectomy from January 1989 to December 2000 comprised the study cohort. A chi-squared metric was used to compare the proportions of patients during three intervals (1989 to 1992, 1993 to 1996, and 1997 to 2000) by categories of PSA level, biopsy Gleason score, clinical T stage, percent positive biopsy cores, age, and risk group, as well as pathologic T stage, Gleason score, margin status, and lymph node status. Actual 2-year PSA recurrence-free survival rates are reported for patients with a minimal follow-up of 24 months, stratified by the interval and preoperative risk group. RESULTS: There was a significant shift in the preoperative characteristics toward younger patients (P <0.0001) with nonpalpable disease (P <0.0001), lower PSA levels (P <0.0001), fewer percent positive biopsies (P <0.0001), and lower preoperative risk group classification (P <0.0001). Pathologically, a significant downward stage migration was found toward organ-confined disease (P <0.0001) and improvement in surgical margin status (P <0.001). The actual 2-year PSA recurrence-free survival rates improved during the three intervals spanning the PSA era from 60% to 78% and 82% (P <0.0001). CONCLUSIONS: With the introduction of serum PSA as a screening tool, we have noted an evolution toward a lower pathologic stage, grade, and improved PSA outcome. These findings provide further support that serum PSA screening increases the proportion of patients potentially curable after radical prostatectomy.

Disease-Free Survival↗

PubMed2002

Bayesian methods for missing covariates in cure rate models.

We propose methods for Bayesian inference for missing covariate data with a novel class of semiparametric survival models with a cure fraction. We allow the missing covariates to be either categorical or continuous and specify a parametric distribution for the covariates that is written as a sequence of one dimensional conditional distributions. We assume that the missing covariates are missing at random (MAR) throughout. We propose an informative class of joint prior distributions for the regression coefficients and the parameters arising from the covariate distributions. The proposed class of priors are shown to be useful in recovering information on the missing covariates especially in situations where the missing data fraction is large. Properties of the proposed prior and resulting posterior distributions are examined. Also, model checking techniques are proposed for sensitivity analyses and for checking the goodness of fit of a particular model. Specifically, we extend the Conditional Predictive Ordinate (CPO) statistic to assess goodness of fit in the presence of missing covariate data. Computational techniques using the Gibbs sampler are implemented. A real data set involving a melanoma cancer clinical trial is examined to demonstrate the methodology.

Bayes Theorem↗