Critz F A, Levinson A K, Williams W H, Holladay D A
Dekalb Medical Center, Atlanta, GA, USA.
J Clin Oncol. 1996 Nov;14(11):2893-900. doi: 10.1200/JCO.1996.14.11.2893.
The prostate-specific antigen (PSA) nadir that reflects potential cure of prostate cancer by irradiation has not been established. This report attempts to demonstrate the PSA nadir goal for radiotherapy.
From January 1984 through April 1994, 536 stage T1T2NO prostate cancer patients were treated with radioactive iodine 125 (125I) prostate implants followed by external-beam radiation. All were staged node-negative: 68% by pelvic node dissection and the remainder by computed tomographic (CT) scan. The mean pretreatment PSA level was 12.4 ng/mL (median, 8.4 ng/mL; range, 0.3 to 188 ng/mL). The median follow-up duration is 40 months (range, 12 to 138). An increasing posttreatment PSA level defined recurrence.
Patients who achieved a PSA nadir < or = 0.5 ng/mL had a 95% (+/- 4%) 5-year and an 84% (+/- 12%) 10-year disease-free survival rate, compared with a 5-year disease-free survival rate of 29% (+/- 30%) for those who reached a nadir of 0.6 to 1.0 ng/mL (P = .0001). All patients with a nadir greater than 1.0 ng/mL ultimately failed. Eighty percent of all 536 patients are projected to achieve a nadir < or = 0.5 ng/mL and 90% of patients who achieve this PSA level do so within 48 months of treatment (median, 18 months). Compared with pretreatment PSA level and histologic grade, the PSA nadir is the most significant factor associated with disease-free survival.
For most patients to be successfully treated for prostate cancer with radiotherapy, at least with this combination technique, the PSA nadir should become undetectable (< or = 0.5 ng/mL), similar to that after radical prostatectomy. A PSA nadir of < or = 0.5 ng/mL after radiotherapy for prostate cancer may be used as a reasonable indicator of 10-year disease-free survival.
反映前列腺癌放疗潜在治愈情况的前列腺特异性抗原（PSA）最低点尚未确定。本报告试图论证放疗的PSA最低点目标。
1984年1月至1994年4月，536例T1T2NO期前列腺癌患者接受了放射性碘125（125I）前列腺植入，随后进行外照射。所有患者均分期为淋巴结阴性：68%通过盆腔淋巴结清扫确定，其余通过计算机断层扫描（CT）检查确定。治疗前PSA平均水平为12.4 ng/mL（中位数为8.4 ng/mL；范围为0.3至188 ng/mL）。中位随访时间为40个月（范围为12至138个月）。治疗后PSA水平升高定义为复发。
PSA最低点≤0.5 ng/mL的患者5年无病生存率为95%（±4%），10年无病生存率为84%（±12%）；而PSA最低点为0.6至1.0 ng/mL的患者5年无病生存率为29%（±30%）（P = 0.0001）。所有最低点大于1.0 ng/mL的患者最终均治疗失败。预计536例患者中有80%的PSA最低点≤0.5 ng/mL，达到该PSA水平的患者中有90%在治疗后48个月内达到此水平（中位数为18个月）。与治疗前PSA水平和组织学分级相比，PSA最低点是与无病生存相关的最显著因素。
对于大多数接受放疗成功治疗的前列腺癌患者，至少采用这种联合技术时，PSA最低点应不可检测（≤0.5 ng/mL），类似于根治性前列腺切除术后的情况。前列腺癌放疗后PSA最低点≤0.5 ng/mL可作为10年无病生存的合理指标。
