Kavadi V S, Zagars G K, Pollack A
Department of Clinical Radiotherapy, University of Texas, M.D. Anderson Cancer Center, Houston 77030.
Int J Radiat Oncol Biol Phys. 1994 Sep 30;30(2):279-87. doi: 10.1016/0360-3016(94)90005-1.
Serum prostate-specific antigen (PSA) levels following definitive radiation for prostate cancer are increasingly recognized as the most sensitive means to monitor disease status. However, beyond general agreement that patients fare poorly when posttreatment PSA levels fail to normalize, many questions relative to postirradiation PSA remain unanswered. This study evaluates the potential prognostic value of postirradiation PSA in a large cohort of patients followed with serial PSA determinations.
We analyzed disease outcome in 427 patients with clinical stages T1 (122 men), T2 (147 men), T3 (152 men), and T4 (six men) prostate cancer receiving definitive external radiation as sole therapy and followed for times ranging from 9-73 months (median 30 months) with a total of 2260 posttreatment PSA values.
Excluding three patients who died due to intercurrent illness without a posttreatment PSA, postirradiation PSA fell in 416 of 424 men (98%). Prostate-specific antigen levels continued to fall for up to 12 months but there was no evidence of significant declines beyond that. The time to nadir PSA was: 3 months, 60 patients; 6 months, 68 patients, 9 months 148 patients; 12 months, 144 patients. Time to nadir was not a significant determinant of outcome. Prostate-specific antigen levels at 3 and 6 months and the nadir level were individually highly correlated with outcome. In multivariate analyses of posttreatment values, only the nadir value was independently significant, with increasing relapse rates as its value was higher. It retained significance when pretreatment PSA level was included in the model. Nadir values ranged from undetectable (52 patients) to 20.3 ng/ml with a median of 1.1 ng/ml. Nadir values down to 1 ng/ml were prognostic; below 1 ng/ml (182 patients) the nadir value no longer yielded prognostic information additional to that inherent in the pretreatment value. Only patients with nadir levels < 1 ng/ml fared well (5-year incidence of relapse or rising PSA 17%); however, if the pretreatment level exceeded 30 ng/ml, then even a nadir level < 1 ng/ml was associated with a 40% failure rate at 5 years.
The nadir PSA value after radiation is a significant posttreatment determinant of outcome and was second only to the pretreatment value. Surprisingly low nadir values were prognostically significant. Only patients whose nadir falls below 1 ng/ml can be said to have achieved a biochemical complete remission. However, even such low nadir values do not portend durable disease control for patients with high pretreatment PSA levels.
前列腺癌根治性放疗后的血清前列腺特异性抗原（PSA）水平日益被视为监测疾病状态的最敏感手段。然而，除了普遍认为治疗后PSA水平未恢复正常的患者预后较差外，许多与放疗后PSA相关的问题仍未得到解答。本研究评估了在一大群接受连续PSA测定随访的患者中，放疗后PSA的潜在预后价值。
我们分析了427例临床分期为T1（122例男性）、T2（147例男性）、T3（152例男性）和T4（6例男性）的前列腺癌患者的疾病转归，这些患者接受了根治性外照射作为唯一治疗，并随访了9至73个月（中位时间30个月），共获得2260个治疗后PSA值。
排除3例因并发疾病死亡且未进行治疗后PSA检测的患者，424例男性中有416例（98%）放疗后PSA下降。前列腺特异性抗原水平持续下降长达12个月，但之后没有显著下降的证据。PSA最低点出现的时间为：3个月，60例患者；6个月，68例患者；9个月，148例患者；12个月，144例患者。最低点出现的时间不是转归的重要决定因素。3个月和6个月时的PSA水平以及最低点水平分别与转归高度相关。在对治疗后值进行多变量分析时，只有最低点值具有独立显著性，其值越高复发率越高。当模型中纳入治疗前PSA水平时，该值仍具有显著性。最低点值范围从不可检测（52例患者）到20.3 ng/ml，中位值为1.1 ng/ml。最低点值降至1 ng/ml具有预后意义；低于1 ng/ml（182例患者）时，最低点值不再提供超出治疗前值固有信息的额外预后信息。只有最低点水平<1 ng/ml的患者预后良好（5年复发或PSA升高发生率为17%）；然而，如果治疗前水平超过30 ng/ml，那么即使最低点水平<1 ng/ml，5年时的失败率仍为40%。
放疗后的PSA最低点值是治疗后转归的重要决定因素，仅次于治疗前值。令人惊讶的是，极低的最低点值具有预后意义。只有最低点降至低于1 ng/ml的患者才能被认为实现了生化完全缓解。然而，即使是如此低的最低点值，对于治疗前PSA水平高的患者也并不预示着疾病能得到持久控制。
