醫生首次將有活性的放射源植入前列腺癌患者體內，這是十五年來近距離放射治療的一項重大革新。

美國IsoRay公司（Richland，WA，USA）研制成功了銫-131（Cesium-131）近距離放射植入活性源，為男性前列腺癌患者提供了一項實用的替代治療手段。華盛頓大學醫療中心（Seattle，WA，USA）的助理教授Leroy Korb博士說：“銫-131活性放射源由IsoRay公司研制成功，該產品與目前市場上其它類型的放射源相比，具有半衰期較短、達到總放射劑量的時間較短的優點。我們相信它將成為男性前列腺癌患者近距離放射治療的有效選擇。”就是在該中心進行了放射源植入患者體內的操作程序。

銫-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天的時間內達到總放射劑量的90％。Korb博士說：“新型銫-131放射源劑量比碘-125更高，在更短的時間內就可以達到更多的放射活性，從而產生最大的治療效果。該治療時間是碘放射源治療的六分之一，而排出體外的時間則要快500天。”

研究者將首個銫-131放射源植入一位74歲的男性體內；操作持續了45～60分鐘。操作者使用針管來植入放射源，這種放射源比一粒大米還小。操作無需切開或者縫合，是一種典型的門診操作方案。患者一般在2～3天后恢復工作和日常活動。由于使用銫-131治療持續時間較短，諸如泌尿系統急癥、小便失禁、或者疼痛等副作用也相應較少。在華盛頓大學前列腺癌研究項目中，大約有50％的患者選擇放射治療而其余50％選擇手術治療。而在其它選擇放射治療患者人群中，大約有30％使用外源性輻射治療，20％使用植入式放射源治療。

Korb博士總結說：“做為IsoRay公司（該公司以華盛頓為基地）的合作伙伴，能夠首次在UV醫療中心提供這種新型治療手段，我們感到非常高興。”

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.