How is PSA used to monitor prostate cancer?
Editor's note: second of two parts; read part one here .
编者注：两部分中的第二部分；在这里阅读第一部分。
In the first part of our series, we described how PSA is used as a screening tool to help detect prostate cancer in men who don't have symptoms.
在我们系列的第一部分中，我们描述了如何使用 PSA 作为筛查工具来帮助检测无症状男性的前列腺癌。
PSA screening can save lives, but it frequently finds slow-growing cancer that might not ever become deadly.
PSA 筛查可以挽救生命，但它经常发现生长缓慢的癌症，这些癌症可能永远不会致命。
Sometimes PSA rises for reasons unrelated to cancer, including inflammation in the prostate, or a benign enlargement of the gland that often occurs with age.
有时 PSA 升高的原因与癌症无关，包括前列腺炎症或随年龄增长而发生的良性腺体肿大。
There are longstanding concerns that PSA screening leads to unnecessary tests and overdiagnosis of prostate cancer.
长期以来，人们担心 PSA 筛查会导致不必要的测试和前列腺癌的过度诊断。
Doctors also measure PSA to check for disease progression in men who have an established cancer diagnosis.
医生还测量 PSA，以检查已确诊癌症的男性的疾病进展情况。
But where PSA screening often yields ambiguous findings, using PSA to monitor cancer progression "is one of the most useful tools we have," says Dr. Marc B.
但是，当 PSA 筛查经常产生不明确的结果时，使用 PSA 监测癌症进展“是我们拥有的最有用的工具之一”，Marc B.
Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and editor-in-chief of the Harvard Medical School Guide to Prostate Diseases .
加尼克是哈佛医学院和贝斯以色列女执事医疗中心的戈尔曼兄弟医学教授，也是哈佛医学院前列腺疾病指南的主编。
Men on active surveillance for low-risk prostate cancer might need treatment if their PSA levels start to rise.
正在积极监测低风险前列腺癌的男性如果 PSA 水平开始上升，可能需要治疗。
Doctors also measure PSA to check for recurring cancer in men who were already treated with surgery or radiation.
医生还测量 PSA，以检查已接受手术或放射治疗的男性是否复发癌症。
But use of the test in such cases differs in important ways
但在这种情况下测试的使用在重要方面有所不同
PSA should be undetectable after a man has his prostate surgically removed.
男性手术切除前列腺后，PSA 应该检测不到。
That's because all PSA-releasing cells should have been taken out.
那是因为所有释放 PSA 的细胞都应该被取出。
If PSA rises during follow-up monitoring, then men have what is called a biochemical recurrence.
如果 PSA 在后续监测期间升高，则男性出现所谓的生化复发。
This means that cancer cells still lurk somewhere in the body.
这意味着癌细胞仍然潜伏在体内的某个地方。
Radiation treatments destroy cancer in the prostate, but leave the rest of the gland intact.
放射治疗可以消灭前列腺中的癌症，但使腺体的其余部分完好无损。
Instead of falling to zero, PSA therefore drops toward what doctors call the nadir, which is the lowest level reached after radiation treatment.
因此，PSA 不会降至零，而是降至医生所说的最低点，即放射治疗后达到的最低水平。
Ideally, the nadir will be less than 1 nanogram of PSA per milliliter of blood (ng/mL), or preferably less than 0.5 ng/mL.
理想情况下，最低点应低于每毫升血液 1 纳克 PSA (ng/mL)，或优选低于 0.5 ng/mL。
A biochemical recurrence in radiation-treated men is diagnosed if their PSA rises by at least 2 ng/mL over the nadir.
如果接受放射治疗的男性 PSA 比最低点上升至少 2 ng/mL，则诊断为生化复发。
Doctors have traditionally looked for cancer after biochemical recurrence by giving men bone scans and computed tomography scans of the abdomen and pelvis.
传统上，医生通过对男性进行骨扫描以及腹部和骨盆的计算机断层扫描来寻找生化复发后的癌症。
If the scans show no evidence of metastases, then men have what's referred to as nonmetastatic prostate cancer.
如果扫描没有显示转移的证据，那么男性就患有所谓的非转移性前列腺癌。
It's called that because rising PSA reveals cancer that the traditional scans are unable to find.
之所以这样称呼，是因为 PSA 的升高可以揭示传统扫描无法发现的癌症。
If the PSA doubles every few years, then such patients can often be followed without need for specific treatments.
如果 PSA 每隔几年翻一番，那么通常可以对此类患者进行随访，而无需特殊治疗。
But if the PSA levels double more rapidly, say every six to eight months, "then we get concerned," Dr. Garnick says.
但如果 PSA 水平更快地翻倍，比如每六到八个月，“那么我们就会担心，”加尼克博士说。
This example illustrates how PSA kinetics -the rate of PSA change over time - can play a very important role in helping doctors determine if there's a need for additional treatment.
这个例子说明了 PSA 动力学（PSA 随时间变化的速率）如何在帮助医生确定是否需要额外治疗方面发挥非常重要的作用。
More recently, doctors have begun using a different test to look for cancer in men with biochemical recurrence.
最近，医生开始使用不同的测试来寻找生化复发男性的癌症。
The test scans for a protein called prostate-specific membrane antigen (PSMA) that most prostate cancer cells have on their surfaces.
该测试扫描大多数前列腺癌细胞表面都有的一种称为前列腺特异性膜抗原（PSMA）的蛋白质。
Doctors start by giving an intravenous tracer that travels the bloodstream, finding and sticking to PSMA.
医生首先给予静脉内示踪剂，该示踪剂会在血液中流动，找到并粘附 PSMA。
Specialized imaging techniques can zero in on the tagged cells, which glow like lit matches in a dark room.
专门的成像技术可以将标记的细胞归零，这些细胞会像暗室中点燃的火柴一样发光。
PSMA is valuable because it can detect tiny metastases that are still too small to see with traditional imaging methods.
PSMA 很有价值，因为它可以检测到传统成像方法仍然太小而无法看到的微小转移。
Doctors measure PSA every three months or so to evaluate how well treatments for metastatic cancer are working.
医生每三个月左右测量一次 PSA，以评估转移性癌症治疗的效果。
If the levels fall or stabilize, then the treatments are effective.
如果水平下降或稳定，则治疗有效。
It used to be that all men with metastatic prostate cancer got lifelong treatment, but therapies are steadily improving.
过去，所有患有转移性前列腺癌的男性都接受终身治疗，但治疗方法正在稳步改进。
Today, long-term treatments can be suspended - sometimes indefinitely - "if PSA remains consistently undetectable and the metastases are no longer visible," Dr. Garnick says.
如今，“如果 PSA 始终检测不到并且转移不再可见，”加尼克博士说，长期治疗可以暂停 - 有时无限期暂停。
PSA is also crucial for evaluating experimental therapies for very advanced forms of prostate cancer.
PSA 对于评估非常晚期前列腺癌的实验疗法也至关重要。
Such therapies can include new drugs or drug combinations that haven't yet been approved by the FDA.
此类疗法可能包括尚未获得 FDA 批准的新药或药物组合。
"A significant drop in PSA of 50% or more is considered a positive indicator of treatment response," Dr. Garnick says.
“PSA 显着下降 50% 或更多被认为是治疗反应的积极指标，”加尼克博士说。
"PSA monitoring continues to be one of the most important evaluations that physicians and clinicians can perform to determine the best treatments for men with prostate cancer."
“PSA 监测仍然是医生和临床医生可以进行的最重要的评估之一，以确定男性前列腺癌的最佳治疗方法。”
C.W.
C.W.
Schmidt , Editor, Harvard Medical School Annual Report on Prostate Diseases
施密特，哈佛医学院前列腺疾病年度报告编辑
Marc B.
马克·B.
Garnick, MD , Editor in Chief, Harvard Medical School Annual Report on Prostate Diseases; Editorial Advisory Board Member, Harvard Health Publishing
Garnick，医学博士，哈佛医学院前列腺疾病年度报告主编；哈佛健康出版社编辑顾问委员会成员
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作为为读者提供的一项服务，哈佛健康出版社提供对我们存档内容库的访问。
Please note the date of last review or update on all articles.
请注意所有文章的最后审查或更新日期。
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
本网站上的任何内容，无论日期如何，都不应替代您的医生或其他合格临床医生的直接医疗建议。
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