D'Amico A V, Hanks G E
Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.
Cancer. 1993 Nov 1;72(9):2638-43. doi: 10.1002/1097-0142(19931101)72:9<2638::aid-cncr2820720919>3.0.co;2-n.
This study was undertaken to calculate the prostate-specific antigen doubling time (PSA-DT) of prostate cancers recurrent after external beam radiation therapy and to investigate if a correlation exists between the PSA-DT and the clinical behavior of prostate cancer as a possible reflection of the tumor doubling time.
Twenty-two patients treated with external beam radiation between October 1985 and October 1990 for clinical stages B1, B2, and C (T2a, T2b, T3) prostate cancer experienced PSA elevation as their only sign of failure. Serial PSA determinations are available before initiation of any secondary treatment and these have been used to calculate PSA-DT.
The results of this study reveal that the PSA-DT is a constant (r > or = 0.98). Mathematically, this means the PSA value is growing exponentially and may represent tumor growth in the exponential phase. Second, the PSA-DT was found to be linearly correlated (r = 0.86) with the interval to clinical relapse after PSA failure. Graphically, the slope of this correlation is equal to the number of PSA-DT (4.5 with 95% confidence interval [3.6]) required before clinical disease manifests after PSA failure. Using this relationship, one can delineate those patients with aggressive tumor biology (PSA-DT < 3.8 months) who require immediate therapeutic intervention versus a relatively indolent tumor biology (PSA-DT > or = 3.8 months) who can be spared the morbidity and expense of androgen deprivation therapy until clinical recurrence manifests. Furthermore, in the pretreatment setting, observation rather than treatment may be indicated for patients with PSA-DT for 18 months or more, because the disease may not become clinically apparent during the patient's lifetime.
PSA-DT after radiation therapy may reflect the tumor doubling time and has implications in the posttherapy setting regarding the optimal time of intervention with androgen deprivation and in the pretreatment setting regarding the necessity for treatment rather than observation.
本研究旨在计算外照射放疗后复发的前列腺癌的前列腺特异性抗原倍增时间（PSA-DT），并探讨PSA-DT与前列腺癌临床行为之间是否存在相关性，以此作为肿瘤倍增时间的一种可能反映。
1985年10月至1990年10月期间，22例接受外照射放疗的临床分期为B1、B2和C期（T2a、T2b、T3）前列腺癌患者，其唯一的失败迹象是PSA升高。在开始任何二次治疗之前可获得系列PSA测定值，并已用于计算PSA-DT。
本研究结果显示PSA-DT是恒定的（r≥0.98）。从数学角度来看，这意味着PSA值呈指数增长，可能代表肿瘤处于指数生长期。其次，发现PSA-DT与PSA失败后至临床复发的间隔呈线性相关（r = 0.86）。从图表上看，这种相关性的斜率等于PSA失败后临床疾病出现前所需的PSA-DT数量（4.5，95%置信区间[3.6]）。利用这种关系，可以区分出具有侵袭性肿瘤生物学行为（PSA-DT<3.8个月）的患者，这些患者需要立即进行治疗干预，而对于具有相对惰性肿瘤生物学行为（PSA-DT≥3.8个月）的患者，可以避免雄激素剥夺治疗的 morbidity 和费用，直到临床复发出现。此外，在治疗前的情况下，对于PSA-DT为18个月或更长时间的患者，可能建议观察而非治疗，因为在患者的一生中疾病可能不会变得临床上明显。
放疗后的PSA-DT可能反映肿瘤倍增时间，在治疗后关于雄激素剥夺的最佳干预时间以及治疗前关于治疗而非观察的必要性方面具有重要意义。
