Leon Sun

BACKGROUND: The relationship between prostate-specific antigen (PSA)-defined recurrence and prostate cancer-specific mortality remains unclear. Therefore, we evaluated the hypothesis that a short post-treatment PSA doubling time (PSA-DT) after radiation therapy is a surrogate end point for prostate cancer-specific mortality by analyzing two multi-institutional databases. METHODS: Baseline, treatment, and follow-up information was compiled on a cohort of 8669 patients with prostate cancer treated with surgery (5918 men) or radiation (2751 men) from January 1, 1988, through January 1, 2002, for localized or locally advanced, non-metastatic prostate cancer. We used a Cox regression analysis to test whether the post-treatment PSA-DT was a prognostic factor that was independent of treatment received. All statistical tests were two-sided. RESULTS: The post-treatment PSA-DT was statistically significantly associated with time to prostate cancer-specific mortality and with time to all-cause mortality (all P(Cox)<.001). However, the treatment received was not statistically significantly associated with time to prostate cancer-specific mortality after PSA-defined disease recurrence for patients with a PSA-DT of less than 3 months (P(Cox) =.90) and for patients with a PSA-DT of 3 months or more (P(Cox) =.28) when controlling for the specific value of the PSA-DT. Furthermore, after a PSA-defined recurrence, a PSA-DT of less than 3 months was statistically significantly associated with time to prostate cancer-specific mortality (median time = 6 years; hazard ratio = 19.6, 95% confidence interval = 12.5 to 30.9). CONCLUSION: A post-treatment PSA-DT of less than 3 months and the specific value of the post-treatment PSA-DT when it is 3 months or more appear to be surrogate end points for prostate cancer-specific mortality after surgery or radiation therapy. We recommend that consideration be given to initiating androgen suppression therapy at the time of a PSA-defined recurrence when the PSA-DT is less than 3 months to delay the imminent onset of metastatic bone disease.

PURPOSE: To determine whether pretreatment risk groups shown to predict time to prostate cancer-specific mortality (PCSM) after treatment at a single institution retained that ability in a multi-institutional setting. PATIENTS AND METHODS: From 1988 to 2002, 7,316 patients treated in the United States at 44 institutions with either surgery (n = 4,946) or radiation (n = 2,370) for clinical stage T1c-2, N0 or NX, M0 prostate cancer made up the study cohort. A Cox regression analysis was performed to determine the ability of pretreatment risk groups to predict time to PCSM after treatment. The relative risk (RR) of PCSM and 95% confidence intervals (CIs) were calculated for the intermediate- and high-risk groups relative to the low-risk group. RESULTS: Estimates of non-PCSM 8 years after prostate-specific antigen (PSA) failure were 4% v 15% (surgery versus radiation; Plog rank =.002) compared with 13% v 18% (surgery versus radiation; Plog rank =.35) for patients whose age at the time of PSA failure was less than 70 as compared with >or= 70 years, respectively. The RR of PCSM after treatment for surgery-managed patients with high- or intermediate-risk disease was 14.2 (95% CI, 5.0 to 23.4; PCox <.0001) and 4.9 (95% CI, 1.7 to 8.1; PCox =.0037), respectively. These values were 14.3 (95% CI, 5.2 to 24.0; PCox <.0001) and 5.6 (95% CI, 2.0 to 9.3; PCox =.0012) for radiation-managed patients. CONCLUSION: This study provided evidence to support the prediction of time to PCSM after surgery or radiation on the basis of pretreatment risk groups for patients with clinically localized prostate cancer managed during the PSA era.

PURPOSE: To determine if obesity is associated with higher prostate specific antigen recurrence rates after radical prostatectomy (RP), and to explore racial differences in body mass index (BMI) as a potential explanation for the disparity in outcome between black and white men. PATIENTS AND METHODS: A retrospective, multi-institutional pooled analysis of 3,162 men undergoing RP was conducted at nine US military medical centers between 1987 and 2002. Patients were initially categorized as obese (BMI > or = 30 kg/m(2)), overweight (BMI 25 to 30 kg/m(2)), or normal (BMI < or = 25 kg/m(2)). For analysis, normal and overweight groups were combined (BMI < 30 kg/m(2)) and compared with the obese group (BMI > or = 30 kg/m(2)) with regard to biochemical recurrence (prostate-specific antigen > or = 0.2 ng/mL) after RP. RESULTS: Of 3,162 patients, 600 (19.0%) were obese and 2,562 (81%) were not obese. BMI was an independent predictor of higher Gleason grade cancer (P <.001) and was associated with a higher risk of biochemical recurrence (P =.027). Blacks had higher BMI (P <.001) and higher recurrence rates (P =.003) than whites. Both BMI (P =.028) and black race (P =.002) predicted higher prostate specific antigen recurrence rates. In multivariate analysis of race, BMI, and pathologic factors, black race (P =.021) remained a significant independent predictor of recurrence. CONCLUSION: Obesity is associated with higher grade cancer and higher recurrence rates after RP. Black men have higher recurrence rates and greater BMI than white men. These findings support the hypothesis that obesity is associated with progression of latent to clinically significant prostate cancer (PC) and suggest that BMI may account, in part, for the racial variability in PC risk.

CONTEXT: Recent studies have suggested that obese men have lower serum prostate-specific antigen (PSA) concentrations than nonobese men. Because men with higher body mass index (BMI) have greater circulating plasma volumes, lower PSA concentrations among obese men may be due to hemodilution. OBJECTIVE: To determine the association between hemodilution and PSA concentration in obese men with prostate cancer. DESIGN, SETTING, AND PARTICIPANTS: Retrospective study of men who underwent radical prostatectomy for prostate adenocarcinoma from 1988 to 2006, using data from the databases of the Shared Equal Access Regional Cancer Hospital (n = 1373), Duke Prostate Center (n = 1974), and Johns Hopkins Hospital (n = 10 287). Multivariate linear regression models adjusting for clinicopathological characteristics were used to analyze the main outcome measures. MAIN OUTCOME MEASURES: Associations between BMI and mean adjusted PSA concentrations, mean plasma volume, and mean adjusted PSA mass (total circulating PSA protein, calculated as PSA concentration multiplied by plasma volume), assessed by determining P values for trend. RESULTS: After controlling for clinicopathological characteristics, higher BMI was significantly associated with higher plasma volume (P < .001 for trend) and lower PSA concentrations (P < or = .02 for trend) in all cohorts. In 2 of the 3 cohorts, PSA mass did not change significantly with increasing BMI. In the third cohort, higher BMI was associated with increased PSA mass (P < .001 for trend), but only between BMI category less than 25 and the other categories. CONCLUSIONS: In men undergoing radical prostatectomy, higher BMI was associated with higher plasma volume; hemodilution may therefore be responsible for the lower serum PSA concentrations among obese men with prostate cancer. Prospective studies are needed to evaluate this association in screened populations.