Ingenito A C, Ennis R D, Hsu I C, Begg M D, Benson M C, Schiff P B
Department of Radiation Oncology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Urology. 1997 Jul;50(1):73-8. doi: 10.1016/S0090-4295(97)00202-1.
To evaluate the prognostic significance of prostate-specific antigen density (PSAD) in clinically localized prostate cancer and determine whether this index is independent of or superior to prostate-specific antigen (PSA) in predicting outcome of patients treated with external beam radiotherapy.
Between January 1989 and December 1993, 175 evaluable patients with clinically localized prostate cancer received definitive radiotherapy using computed tomography (CT)-guided conformal techniques. PSAD was defined as the ratio of the pretreatment serum PSA to the prostate volume measured from CT treatment planning scans by one investigator. All PSA values were determined using the Hybritech assay. Biochemical failure was defined as two consecutive elevations in PSA separated by at least 3 months and a final PSA value greater than 1 ng/mL.
Multivariate analysis including PSA and Gleason score revealed both to be statistically significant predictors of biochemical disease-free survival (P = 0.048 and P < 0.001, respectively). PSAD did not achieve significance on regression analysis. A direct multivariate analysis including PSA and PSAD required dichotomization in order to reduce high correlation. This analysis demonstrated a relative risk (RR) for failure of 1.27 (NS) for high PSA versus low PSA compared with a RR of 1.20 (NS) for high PSAD versus low PSAD. A regression model containing all three variables indicated only the Gleason score as significant in predicting biochemical failure.
These data do not suggest that PSAD is either an independent prognostic factor or a stronger discriminant of outcome than PSA in patients with clinically localized prostate cancer treated with definitive external beam radiotherapy. Larger patient numbers with longer follow-up data, use of a clinical end point, or an analysis restricted to the appropriate subgroup may demonstrate the utility of PSAD in the future.
评估前列腺特异性抗原密度（PSAD）在临床局限性前列腺癌中的预后意义，并确定该指标在预测接受外照射放疗患者的预后方面是否独立于前列腺特异性抗原（PSA）或优于PSA。
1989年1月至1993年12月期间，175例可评估的临床局限性前列腺癌患者接受了计算机断层扫描（CT）引导的适形技术的根治性放疗。PSAD定义为一名研究人员根据CT治疗计划扫描测量的治疗前血清PSA与前列腺体积之比。所有PSA值均使用Hybritech检测法测定。生化失败定义为PSA连续两次升高，间隔至少3个月，且最终PSA值大于1 ng/mL。
包括PSA和Gleason评分的多变量分析显示，两者均为生化无病生存的统计学显著预测因子（分别为P = 0.048和P < 0.001）。PSAD在回归分析中未达到显著性。包括PSA和PSAD的直接多变量分析需要进行二分法以降低高相关性。该分析显示，高PSA与低PSA相比，失败的相对风险（RR）为1.27（无统计学意义），而高PSAD与低PSAD相比，RR为1.20（无统计学意义）。包含所有三个变量的回归模型表明，只有Gleason评分在预测生化失败方面具有显著性。
这些数据并不表明PSAD在接受根治性外照射放疗的临床局限性前列腺癌患者中是一个独立的预后因素，也不比PSA更能区分预后。未来，更大规模的患者群体、更长的随访数据、使用临床终点或仅限于适当亚组的分析可能会证明PSAD的实用性。
