IsoRay公司研制成功用于治疗前列腺癌的铯-131放射源

医生首次将有活性的放射源植入前列腺癌患者体内，这是十五年来近距离放射治疗的一项重大革新。

美国IsoRay公司（Richland，WA，USA）研制成功了铯-131（Cesium-131）近距离放射植入活性源，为男性前列腺癌患者提供了一项实用的替代治疗手段。华盛顿大学医疗中心（Seattle，WA，USA）的助理教授Leroy Korb博士说：“铯-131活性放射源由IsoRay公司研制成功，该产品与目前市场上其它类型的放射源相比，具有半衰期较短、达到总放射剂量的时间较短的优点。我们相信它将成为男性前列腺癌患者近距离放射治疗的有效选择。”就是在该中心进行了放射源植入患者体内的操作程序。

铯-131放射源的半衰期是9.7天，而碘-125的半衰期是60天。它可以在不到33天的时间内达到总放射剂量的90％。Korb博士说：“新型铯-131放射源剂量比碘-125更高，在更短的时间内就可以达到更多的放射活性，从而产生最大的治疗效果。该治疗时间是碘放射源治疗的六分之一，而排出体外的时间则要快500天。”

研究者将首个铯-131放射源植入一位74岁的男性体内；操作持续了45～60分钟。操作者使用针管来植入放射源，这种放射源比一粒大米还小。操作无需切开或者缝合，是一种典型的门诊操作方案。患者一般在2～3天后恢复工作和日常活动。由于使用铯-131治疗持续时间较短，诸如泌尿系统急症、小便失禁、或者疼痛等副作用也相应较少。在华盛顿大学前列腺癌研究项目中，大约有50％的患者选择放射治疗而其余50％选择手术治疗。而在其它选择放射治疗患者人群中，大约有30％使用外源性辐射治疗，20％使用植入式放射源治疗。

Korb博士总结说：“做为IsoRay公司（该公司以华盛顿为基地）的合作伙伴，能够首次在UV医疗中心提供这种新型治疗手段，我们感到非常高兴。”

First Use of Cesium-131 to Treat Prostate Cancer

In the first major innovation in brachytherapy in more than 15 years, physicians have for the first time implanted a new kind of radioactive seed in a prostate cancer patient.

The cesium-131 (Cs-131) brachytherapy implant seed was developed by IsoRay (Richland, WA, USA; www.isoray.com) and provides another practical alternative for men with prostate cancer. “The Cs-131 seed developed by IsoRay offers a shorter half-life and faster delivery of the total radiation dose than the other types of seeds currently on the market. We believe it will be an effective option for men choosing brachytherapy to treat their prostate cancer,” said Dr. Leroy Korb, assistant professor of radiation oncology at the University of Washington Medical Center (Seattle, WA, USA; www.uwmedicine.org), where the implantation procedure was performed.

The Cs-131 seed has a half-life of 9.7 days, compared to 60 days for the iodine-125 seed. It delivers more than 90% of its total radiation dose in less than 33 days. “The new Cs-131 seed has a significantly higher dose rate than iodine, allowing for the delivery of more radiation in a shorter period of time to maximize its effectiveness. The treatment is over in one-sixth the time of iodine seeds and leaves the body 500 days faster,” said Dr. Korb.

The investigators will implant the first Cs-131 seeds in a 74-year-old man; the procedure takes about 45 to 60 minutes. Needles are used to implant the seeds, which are smaller than a grain of rice. No incision or suturing is necessary, and it is typically an outpatient procedure. The patient is usually back to work and daily activities within two to three days. Because of the shorter duration of treatment with Cs-131, side effects may be lessened, such as urinary urgency, incontinence, or pain. In the University of Washington prostate cancer program, approximately 50% have chosen radiation treatment and the other 50% have chosen surgery. Out of the group that chose radiation, approximately 30% had external beam radiation and 20% had implanted seeds.

“We are very pleased to be the first to offer this new type of treatment at UV Medical Center, and to partner with IsoRay, a Washington-based company,” concluded Dr. Korb.