Schmid H P, McNeal J E, Stamey T A
Department of Urology, Stanford University School of Medicine, California.
Cancer. 1993 Mar 15;71(6):2031-40. doi: 10.1002/1097-0142(19930315)71:6<2031::aid-cncr2820710618>3.0.co;2-q.
The serum marker prostate-specific antigen (PSA) has been shown to be proportional to the volume of prostate cancer (Yang polyclonal assay). One gram of cancer on average produces 3.5 ng/ml of PSA elevation. Thus, changes in PSA in untreated patients should reflect tumor growth rate and the shape of the growth curve.
Forty-three patients with previously untreated prostate cancer had serial PSA determinations during a period of at least 12 months (mean, 30 months; range, 12-63 months). There was no treatment between the initial and final PSA. PSA was measured five or more times in half of these patients. Log-PSA values were plotted versus time, tested for linearity, and compared between different clinical stages and histologic grades.
PSA values increased with time in 86% of patients but remained stable in 14%. The increase of PSA was exponential (log-linear) throughout the measured interval. Doubling times were faster in patients with higher disease stages and grades. Seventy-nine percent of all patients had a doubling time of more than 24 months. Twenty of 28 cancers thought to be clinically organ confined doubled at rates exceeding 48 months. Tumor doubling times were overestimated in patients with large-volume benign prostatic hyperplasia because hyperplasia increases serum PSA at an average rate of 0.3 ng/ml.
The authors conclude that prostate cancer has a constant (log-linear) growth rate that is very slow. This extraordinarily slow doubling time has substantial consequences for therapeutic decisions and for screening programs.
血清标志物前列腺特异性抗原（PSA）已被证明与前列腺癌体积成正比（杨多克隆检测法）。平均每克癌组织可使PSA升高3.5 ng/ml。因此，未经治疗患者的PSA变化应反映肿瘤生长速率及生长曲线形态。
43例未经治疗的前列腺癌患者在至少12个月（平均30个月；范围12 - 63个月）内进行了系列PSA测定。初始和末次PSA测定期间未进行治疗。其中一半患者进行了5次或更多次PSA测量。将对数PSA值与时间作图，检测线性关系，并在不同临床分期和组织学分级之间进行比较。
86%的患者PSA值随时间升高，但14%的患者保持稳定。在整个测量区间内，PSA升高呈指数形式（对数线性）。疾病分期和分级较高的患者倍增时间更快。所有患者中有79%的倍增时间超过24个月。28例临床认为局限于器官内的癌中有20例倍增速率超过48个月。前列腺体积较大的良性前列腺增生患者的肿瘤倍增时间被高估，因为增生使血清PSA平均以0.3 ng/ml的速率升高。
作者得出结论，前列腺癌具有恒定（对数线性）的生长速率，且非常缓慢。这种异常缓慢的倍增时间对治疗决策和筛查计划具有重大影响。
