前列腺癌的高剂量率近距离放射治疗

放疗是前列腺癌根治的重要治疗手段，前列腺癌的近距离放射是近20年来前列腺癌治疗领域的研究热点。多年来早期局限性前列腺癌的近距离放射以低剂量率放射粒子植入为主，但近年来美国各肿瘤治疗中心已逐渐开展了针对局限性前列腺癌的高剂量率（hish-dose-rate，HDR）近距离放射。多项研究结果显示前列腺癌具有低α/β比值，故大分割放射的高剂量率近距离放射对前列腺癌可能更具疗效。HDR近距离放射治疗通常与外放疗联合应用于局部晚期的前列腺癌根治，临床研究结果已初步证实了这一治疗方案的疗效；另外，单一HDR近距离放射治疗也可用于早期前列腺癌的治疗，但其疗效仍需临床研究的进一步支持。HDR近距离放射技术需要经过特殊训练的医师方能操作，以保证良好的治疗结果。     

前列腺癌近距离治疗进展

前列腺癌治疗主要包括根治性手术、外放疗和近距离放射治疗、内分泌治疗。近距离治疗兴起于20世纪80年代,成为前列腺癌治疗的热点。目前主要有永久性放射性粒子植入及高剂量率（highdose—rate,HDR）近距离治疗。     

高剂量率近距离放射治疗在前列腺癌治疗中的应用

20世纪80年代欧洲和美国开始运用高剂量率(high dose rate,HDR)近距离放射疗法治疗中高危前列腺癌。HDR作为剂量提升的有效方法可与外照射联合应用。William Beaumont医院剂量提升研究证实这种联合治疗安全有效。研究表明前列腺癌α/β比值远低于之前的认识,前列腺癌放射生物学认识发生巨大转变。单次剂量高于常规剂量照射的大分割模式应运而生。低毒和联合外照射治疗临床研究,使高剂量率近距离放射治疗趋于成为低中危前列腺癌治疗唯一有效的器官保留治疗方式,开启前列腺癌治疗器官保留治疗新时代,本文旨在对HDR联合外照射疗法和单一HDR疗法的文献进行回顾,对临床结果及毒性反应进行分析。     

放射性粒子组织间近距离治疗早期前列腺癌

前列腺癌治疗包括根治性手术、外放疗和组织间近距离治疗。组织间近距离治疗由于具有局部剂量高和副作用轻而易于被患者接受,目前已经成为美国早期前列腺癌的标准治疗手段之一。本文综述了前列腺癌近距离治疗的历史、技术方法、适应证和并发证。     

高剂量率支气管内近距离放疗根治局限性支气管内肺癌

随着小型化放射源~(192)Ir及后装机技术的发展,目前 已能对支气管腔内肺癌进行近距离放疗。现在提倡的高剂量率(HDR)(>10Gy/h)支气管内近距离放疗具有下列优点:缩短治疗时间。便于门诊病人;剂量与放射源距离呈反平方关系。迅速衰减,故治疗区严格限制于肿瘤及其周边组织,给予病人以最大的放射保护。该方法已面功应用于解除肿瘤性支气管阻塞及联合外照射根治支气管腔内肺癌,但用于支气管内小病灶的根治性治疗仅适用于少数病例。本文旨在研究HDR支气管内近距离放疗对于因严重呼吸衰竭或原先已经治疗而不适合采用其他治疗的局限性支气管内肿瘤患者作为单一治疗的应用价值。     

近距离放疗剂量学方法(一)——放射源的刻度方法

源外观活度的刻度是近距离放疗剂量学基本内容,刻度精度直接影响治疗剂量准确性。本文着重介绍核通公司micro selectron—HDR后装机微型192Ir源的刻度方法。     

经会阴永久性近距离治疗前列腺癌指南解读

前列腺癌治疗方法主要包括根治性前列腺切除术、冷冻治疗、外放疗、调强放射治疗以及组织间近距离治疗。经会阴前列腺近距离放疗是治疗前列腺癌的有效方法,完善的病例选择标准及质量保证体系对于手术成功实施必不可少,基于此,本文对经会阴永久性近距离治疗前列腺癌指南进行了分析。     

编者的话

本期刊登了肺癌、食管癌、胰腺癌、直肠癌、前列腺癌、鼻咽癌、舌癌等恶性肿瘤,应用微型多功能高剂量率后装治疗机(Micro—Selectron—HDR),通过腔内或组织间插植的近距离放射治疗,取得了明显的近期临床效果。对这些恶性肿瘤从单纯体外放射治疗走向体内与体外联合放疗,这是放射治疗手段一项重大进展。近距离的放射治疗的作用提高了肿瘤的局部控制率,降低放射治疗的并发症,保留了某些主要器官功能,提高了病人的生存质量。本期仅仅介绍了应用微型多功能后装机治疗几种恶性肿瘤的近期临床效果是一良好开端。但是一项新技术的开发,尚需进行较多病种的临床探索,开展近距离放疗的基础研究,制定合理的     

高剂量率~(192)Ir后装近距离放疗中晚期直肠癌(附38例分析)

目的:分析高剂量率192Ir后装近距离放疗在中晚期直肠癌治疗中的价值。方法:38例中晚期直肠癌,综合组高剂量率192Ir后装近距离放疗结合外照射放疗20例,对照组单纯外照射18例。高剂量率192Ir后装近距离放疗根据肿瘤形态采用组织间插植术和腔内放疗,2周4次完成,总剂量24Gy～28Gy。1周后加外照射。对照组外照射盆腔野总剂量45Gy～50Gy,2次/d。结果:临床证状改善、局部肿瘤消退情况综合组高剂量率192Ir后装近距离放疗2周疗效与对照组外照射40Gy无明显差异。综合组较单纯外照组提高了1a、3a生存率。结论:高剂量率192Ir后装近距离放疗在晚期直肠癌治疗中有较好的疗较。提高生存率需结合盆腔野外照射放疗。     

近距离放射治疗的临床应用进展

近距离放疗是现代放射肿瘤学的初始技术和不可缺少的组成部分。近年来，除了在妇科肿瘤和头颈部等肿瘤中仍继续被广泛应用外，单纯放射性粒子组织间放疗已成为早期前列腺癌的标准治疗手段之一，单纯近距离放疗可成为早期乳腺癌保乳术后放疗主要选择方法之一。本文重点介绍2005年美国放射肿瘤治疗学年会（ASTRO）中关于近距离放疗临床应用的现状，展望未来发展的方向。     

High dose rate afterloading brachytherapy for prostate cancer: catheter and gland movement between fractions.

Fractionated high dose rate afterloading brachytherapy for prostate cancer requires a robust means of catheter fixation with good quality assurance. Catheter position and dosimetry has been formally evaluated in 20 consecutive patients representing a total of 332 catheters undergoing two HDR afterloading brachytherapy fractions over 36 h. The mean interfraction movement of catheters as measured by external length was less than 1 mm, but within the prostate on consecutive CT scans there was a mean interfraction movement of 11.5 mm away from the prostate base. This has a significant impact on implant dosimetry as measured by D90 and the COIN index, unless corrected by repositioning the catheters.     

Iodine‐125 brachytherapy for prostate cancer: First published Australian experience

With the emergence of new imaging and implant techniques, prostate brachytherapy has become increasingly popular over the last decade. Brachytherapy promises to deliver twice the biologically effective dose as conventional external beam treatments without increasing the dose to tissues surrounding the prostate. However, there are few or no published Australian series of its efficacy in the clinic. We present the experience of one of the first centres in Australia to offer this service to its patients: a series from Sir Charles Gairdner Hospital in Western Australia. We present data on the efficacy of brachytherapy in maintaining prostate specific antigen levels, as well as the rate of urinary, rectal and sexual complications. Our results compare favourably with other brachytherapy and external beam treatment series. We believe that with the increasing trend towards dose escalation and novel therapies, standardized measurements of success and failure need to be better defined, and that randomized trials comparing modalities are needed to improve the management of prostate cancer.     

Interstitial implantation techniques in prostate cancer

Brachytherapy is a radiotherapeutic technique that allows the physician to implant radioactive isotopes into a body cavity or directly into tissue. Different radioisotopes have unique characteristics that the brachytherapist may utilize for a particular situation. The use of brachytherapy is part of standard radiation oncology practice in gynecological and head and neck cancer management. The prostate is approachable for interstitial implantation due to its close proximity to the perineum. Over 20 years ago, primitive methods of brachytherapy were utilized in the treatment of prostate cancer. However, poor results due to inconsistency in achieving adequate coverage of the entire prostate and poor patient selection caused this treatment modality to fall out of favor. Technological advances over the last decade have restored attention to brachytherapy for prostate cancer. Particularly important has been the development of transrectal ultrasound, new radioisotopes such as palladium-103, computer tomography, computerized dosimetry systems, and earlier diagnosis. Modern interstitial implantation utilizing transperineal template and transrectal ultrasound guidance has resulted in improved consistency in radiation dose delivery to the entire prostate. Early results are encouraging in terms of the relatively low morbidity of the procedure, improved local control rates, and biochemical progression free survival. This has resulted in an outpatient treatment that has high patient acceptance. J. Surg. Oncol. 1997;66:65–75. © 1997 Wiley-Liss, Inc.     

High dose rate brachytherapy for prostate cancer: Standard of care and future direction

High dose rate brachytherapy is a highly conformal method of radiation dose escalation for prostate cancer and one of several treatment options for men with localised disease. The large doses per fraction exploit the low alpha/beta ratio of prostate cancer cells so that biological radiation dose delivered is substantially greater than that achieved with conventional external beam delivery. This review article presents contemporary data on the rationale for high dose rate brachytherapy including treatment technique and future directions.     

The Role of Magnetic Resonance Imaging in Brachytherapy

The application of magnetic resonance imaging (MRI) in image-guided brachytherapy has expanded rapidly over the past two decades. In cervix cancer, significant improvements in overall survival, local control and long-term morbidity have been shown in patients treated with MRI-guided brachytherapy, changing clinical practice and directing an international approach to standardise the technique; unifying adaptive target volume definition and dose reporting. MRI-guided prostate brachytherapy has significantly improved the accuracy of tumour and organ-at-risk delineation, facilitating targeted implantation and dose optimisation. It also has potential to improve clinical outcomes through enhancement of the therapeutic ratio and the identification of dominant lesions that can be the targets of sub-volume boosting and salvage therapy. However, MRI-guided brachytherapy presents a number of logistical and financial challenges in modern healthcare systems, requiring technologically advanced imaging and planning techniques, as well as robust safety and quality assurance procedures. A collaborative, multidisciplinary approach involving clinical oncologists, radiologists, medical physicists, therapy radiographers, nurses and technical staff is therefore critical to its successful incorporation into any clinical brachytherapy workflow. In this overview we evaluate the current role of MRI in image-guided brachytherapy, primarily in cervix and prostate cancer, but also in other tumour sites, and review its potential future developments in the context of both clinical and research spheres.     

High Dose Rate Brachytherapy in High-Risk Localised Disease – Why Do Anything Else?

The management of high-risk prostate cancer is challenging, as patients have a high risk of both local and distant relapse. Although adjuvant systemic treatment remains an important component of management, for those receiving radiotherapy, optimal local treatment should include a brachytherapy boost. This may be given by low dose rate (LDR) or high dose rate (HDR) techniques, but HDR has several advantages over LDR by virtue of more consistent dose optimisation, ability to treat outside the prostate and lower toxicity. A significant body of evidence now supports the use of HDR brachytherapy in addition to supplementary pelvic external beam radiotherapy for men with high-risk disease. Consistent evidence has emerged from randomised clinical trials, meta-analyses, and from institutional and multicentre cohort studies. It has been shown to improve local disease control and possibly reduce metastases and improve cancer-specific survival compared with external beam radiotherapy alone. It should be considered as standard treatment.     

Ultrahypofractionated Radiotherapy for Localised Prostate Cancer: How Far Can We Go?

Following adoption of moderately hypofractionated radiotherapy as a standard for localised prostate cancer, ultrahypofractioned radiotherapy delivered in five to seven fractions is rapidly being embraced by clinical practice and international guidelines. However, the question remains: how low can we go? Can radiotherapy for prostate cancer be delivered in fewer than five fractions? The current review summarises the evidence that radiotherapy for localised prostate cancer can be safely and effectively delivered in fewer than five fractions using high dose rate brachytherapy or stereotactic body radiotherapy. We also discuss important lessons learned from the single-fraction high dose rate brachytherapy experience.     

Present and future in brachytherapy--from the discovery of radium to the 21st century]

Brachytherapy can deliver high doses of radiation to a tumor with only low doses to the normal tissue. Brachytherapy can be classified as intracavitary, intraluminar and interstitial radiotherapy. It can be also divided into three groups according to dose rate: low (LDR), medium (MDR) and high (HDR) dose rates. In recent years, HDR remotely controlled afterloading systems are widespread in Japan. HDR brachytherapy has solved the problem of radiation exposure for medical staff, and patients need not be isolated in highly sealed rooms. Local control rates of T1 and T2 tongue cancer treated with LDR interstitial radiation using 226Ra and 192Ir were 80% and 67%. A phase III trial of HDR versus LDR interstitial brachytherapy for early tongue cancer revealed the same local control rates between the two groups. For uterine cervix cancer, the cause-specific survival rates of patients treated with HDR intracavitary brachytherapy were almost the same as those treated with LDR. HDR brachytherapy can be applied against recurrent tumors. Almost half of recurrent tumors can be controlled with HDR treatment. Brachytherapy is widely used for prostate cancer in the USA. LDR brachytherapy using 125I seeds is used for prostate cancer. In Japan, 125I seeds can not be used because of the regulation of radioisotopes, so we treat prostate cancer patients with HDR brachytherapy. The two-year biochemical NED rate is 83%. Brachytherapy has a long history of nearly 100 years. In recent years, the development of an HDR remotely controlled afterloading system and treatment planning system allows us to make a precise treatment plan and a uniform dose distribution. In the next century, HDR-brachytherapy will continue to play an important role in the field of radiotherapy.     

Permanent prostate brachytherapy in men with clinically localised prostate cancer

Permanent prostate brachytherapy techniques are associated with excellent biochemical control for patients with localised prostate cancer. Ten-year data show that permanent prostate brachytherapy is compatible with external beam irradiation or radical prostatectomy. However, treatment protocols and techniques for prostate brachytherapy vary between centres and there is little conformity of treatment protocols. The selection of patients for monotherapy or combined external beam irradiation and brachytherapy is controversial. The role of neoadjuvant androgen deprivation also remains unanswered in patients with localised prostate cancer. In addition, post-implant dosimetry may in fact be more significant for predicting outcome than the addition of adjuvant therapies, and should be a requirement when performing prostate brachytherapy. Data now seem to support specific computed tomography (CT)-based criteria to evaluate implant quality and delivered dose to the prostate. Unfortunately, prostate oedema and poor imaging techniques are limiting factors for evaluating implant dosimetry. Treatment planning techniques that use new treatment planning computers may assist in improving the implant procedure and dosimetry and are now available.     

Advances in brachytherapy--focusing on the permanent implant for early prostate carcinoma

Even in the modern era of advanced external radiotherapy, brachytherapy is an important and useful modality of radiotherapy. In North America and Europe, it has been noted that the proportion of prostate cancer patients treated by HDR or LDR interstitial brachytherapy is rapidly increasing, as it offers several practical and theoretical advantages over external radiotherapy. HDR treatment with 192Ir remote afterloader provides an optimized dose distribution controlled by an accurate dwell time and position of 192Ir source. LDR brachytherapy is a simple, minimally invasive, and outpatient based procedure that avoids hospitalization and allows the patient an early recovery and rapid return to normal activities. It has produced good 10-year outcome with relatively low morbidity. Although in Japan this treatment was behind North America and Europe, the 125I-seed source was approved by the Japanese FDA and a rule for patient discharge was developed recently. The first case was treated in September 2003 and this treatment is expected to become an important option for early prostate cancer. Several areas of brachytherapy including treatment planning, choice of radionuclide, treatment procedure, and treatment outcome are discussed in this paper.