Accelerated partial breast irradiation using interstitial high dose rate brachytherapy: preliminary clinical and dosimetric results after 61 patients

PURPOSE: Among all the accelerated and partial breast irradiation (APBI) techniques, low then high dose rate, interstitial brachytherapy (HDIB) was the first to be used in this field. This study presents the preliminary clinical and dosimetric results of the APBI using HDIB, performed in Antoine Lacassagne Cancer Center of Nice. PATIENTS AND METHODS: From June 2004 to March 2008, 61 patients (37 primary tumors and 24 second conservative treatments after local recurrence) presenting with T1-2 pN0 non-lobular invasive breast carcinoma, underwent lumpectomy with sentinel lymph node dissection and intraoperative tube placement for HDIB. Dose distribution analysis, using dose-volume histograms, was achieved based on a postoperative CT scan. A comparative dosimetric study was performed between optimized (O) and non-optimized (NO) dose distribution. Then, based on conformal index calculation, a novel index was proposed taking into account not only the conformity but also the homogeneity of HDIB implant. An analysis of dose gradient impact on HDIB biological equivalence dose was also conducted. Statistical analysis used T test confirmed by Wilcoxon test for cohort including less than 30 patients. RESULTS: The comparative dosimetric analysis between O and NO dose distributions shown that conformity indexes (conformal index, conformal number, and D90%) were significantly increased after optimization. Improving conformity leads to increasing hyperdosage volumes (V150% and V200%). A new index named conformity and homogeneity index (CHI) including V150% values, modified the conformal index. A total dose of 34 Gy, delivered through HDIB in 10 fractions over five days was biologically equivalent to 41.93 Gy assuming alpha/beta = 4 Gy and 75.76 Gy if the dose gradient was considered in the calculation. CONCLUSIONS: HDIB is considered as one of the best IPAS technique. HDIB allows dose distribution optimization, skin spearing and accurate clinical target volume definition. Furthermore, HDIB dose gradient could play a key role for breast cancer local control.     

Initial dosimetric experience using simple three-dimensional conformal external-beam accelerated partial-breast irradiation

PURPOSE: Several accelerated partial-breast irradiation (APBI) techniques are being investigated in patients with early-stage breast cancer. We present our initial experience using three-dimensional conformal radiation therapy (3D-CRT). METHODS AND MATERIALS: Sixty-one patients with tumors of 2 cm or less and negative axillary nodes were treated with 3D-CRT accelerated partial-breast irradiation (APBI) between August 2003 and March 2005. The prescribed radiation dose was 32 Gy in 4-Gy fractions given twice daily. Efforts were made to minimize the number of beams required to achieve adequate planning target volume (PTV) coverage. RESULTS: A combination of photons and electrons was used in 85% of patients. A three-field technique that consisted of opposed, conformal tangential photons and enface electrons was employed in 43 patients (70%). Nine patients (15%) were treated with a four-field arrangement, which consisted of three photon fields and enface electrons. Mean PTV volumes that received 100%, 95%, and 90% of the prescribed dose were 93% +/- 7%, 97% +/- 4%, and 98% +/- 2%, respectively. Dose inhomogeneity exceeded 10% in only 7 patients (11%). Mean doses to the ipsilateral lung and heart were 1.8 Gy and 0.8 Gy, respectively. CONCLUSIONS: Simple 3D-CRT techniques of APBI can achieve appropriate PTV coverage while offering significant normal-tissue sparing. Therefore, this noninvasive approach may increase the availability of APBI to patients with early-stage breast cancer.     

Indications potentielles de la tomothérapie hélicoïdale dans les cancers du sein

PurposeTo evaluate the dosimetric gain obtained in either the planning target volume or organs at risk coverage by the use of intensity-modulated radiation therapy in some particular postoperative breast cancers.Patients and methodProspective dosimetric comparison between monoisocentric conformal radiotherapy and intensity-modulated radiation therapy in nine patient files.ResultsUsing intensity-modulated radiation therapy was shown to improve in each case, at least one conformity, homogeneity, and coverage index either for planning target volumes or for organs at risk. Intensity-modulated radiation therapy was therefore always chosen rather than conformal monoisocentric radiotherapy.ConclusionsIndications to retain intensity-modulated radiation therapy would consist of bilateral lesions, pectus excavatum, past thoracic irradiation (Hodgkin's disease) and complex volumes in obese or overweight patients.     

Accelerated partial breast irradiation

Whole breast irradiation (WBI) is the standard after breast conservation surgery. However, WBI in selected patients has been questioned. Accelerated partial breast irradiation (APBI) focuses treatment on the lumpectomy bed. Many modalities of delivering APBI have been developed: multicatheter interstitial brachytherapy, MammoSite balloon catheter, single insertion multicatheter devices, three-dimensional conformal external-beam radiation therapy and intraoperative techniques. Numerous studies of APBI have demonstrated excellent local control and cosmetic outcomes in early-stage breast cancer patients.     

Current status of accelerated partial breast irradiation

Accelerated partial breast irradiation (APBI) is a radiotherapy method used in breast-conserving therapy. In APBI, the tumor bed is topically irradiated over a short period after breast-conserving surgery. The fundamental concept underlying APBI is that more than 70% of ipsilateral breast tumor recurrence occurs in the neighborhood of the original tumor, and that hypofractionated radiotherapy can be applied safely when the irradiated volume is small enough. It is expected to reduce the time and cost required for conventional whole breast irradiation while maintaining equivalent local control. Several techniques including multicatheter interstitial brachytherapy, intracavitary brachytherapy, intraoperative radiation therapy, and 3D conformal external beam radiation therapy have been proposed, and each of them has its own advantages and drawbacks. Although APBI is increasingly used in the United States and Europe, and the short-term results are promising, its equivalence with whole breast radiation therapy is not fully established. In addition, because the average breast size in Japan is considerably smaller than in the West world, the application of APBI to Japanese patients is technically more challenging. At this point, APBI is still an investigational treatment in Japan, and the optimal method of radiation delivery as well as its long-term efficacy and safety should be clarified in clinical trials.     

Evaluating target coverage and normal tissue sparing in the adjuvant radiotherapy of malignant pleural mesothelioma: helical tomotherapy compared with step-and-shoot IMRT.

PURPOSE: To evaluate the potential of helical tomotherapy in the adjuvant treatment of malignant pleural mesothelioma and compare target homogeneity, conformity and normal tissue dose with step-and-shoot intensity-modulated radiotherapy. METHODS AND MATERIALS: Ten patients with malignant pleural mesothelioma who had undergone neoadjuvant chemotherapy with cisplatin and permetrexed followed by extrapleural pneumonectomy (EPP) were treated in our department with 54 Gy to the hemithorax delivered by step-and-shoot IMRT. A planning comparison was performed by creating radiation plans for helical tomotherapy. The different plans were compared by analysing target homogeneity using the homogeneity indices HI(max) and HI(min) and target conformity by using the conformity index CI(95). To assess target coverage and normal tissue sparing TV(90), TV(95) and mean and maximum doses were compared. RESULTS: Both modalities achieved excellent dose distributions while sparing organs at risk. Target coverage and homogeneity could be increased significantly with helical tomotherapy compared with step-and-shoot IMRT. Mean dose to the contralateral lung could be lowered beyond 5 Gy. CONCLUSIONS: Our planning study showed that helical tomotherapy is an excellent option for the adjuvant intensity-modulated radiotherapy of MPM. It is capable of improving target coverage and homogeneity.     

乳腺癌保乳术后加速部分乳腺照射的研究进展

传统的乳腺癌保乳术后放疗是对全乳腺进行5周-6周的放疗。随着放射治疗技术的发展,加速部分乳腺照射可能会成为另一选择。该文就加速部分乳腺照射在乳腺癌治疗中的研究进展作一综述。     

乳腺癌保乳术后加速部分乳腺照射研究进展

保乳手术加术后全乳腺放疗(whole breast irradiation, WBI)已成为早期乳腺癌的标准治疗模式之一, 但是传统的WBI照射范围大, 疗程长。近年来, 缩小照射范围、缩短总疗程的加速部分乳腺照射(accelerated partial breast irradiation, APBI)作为保乳术后WBI的替代治疗方法, 得到了广泛的认同。APBI常用的治疗方式有术中放疗、外照射和近距离放疗三种。术中放疗为保乳手术中给予一次性照射, 照射范围准确, 但是对设备的要求较高。外照射由专业的放疗科医师和物理师执行, 相对容易实现, 而且可以通过治疗计划系统使靶区剂量均匀分布。近距离治疗目前常用的有组织间插植和mammosite球囊治疗, mammosite设备技术简单、实施容易, 目前应用较广泛。然而, 由于APBI技术应用时间尚短、临床随访数据有限, 应用时必须进行严格的病例筛选以及合理的计划, 以降低局部复发的风险。      

Tumor bed delineation for external beam accelerated partial breast irradiation: A systematic review

In recent years, accelerated partial breast irradiation (APBI) has been considered an alternative to whole breast irradiation for patients undergoing breast-conserving therapy. APBI delivers higher doses of radiation in fewer fractions to the post-lumpectomy tumor bed with a 1–2 cm margin, targeting the area at the highest risk of local recurrence while sparing normal breast tissue. However, there are inherent challenges in defining accurate target volumes for APBI. Studies have shown that significant interobserver variation exists among radiation oncologists defining the lumpectomy cavity, which raises the question of how to improve the accuracy and consistency in the delineation of tumor bed volumes. The combination of standardized guidelines and surgical clips significantly improves an observer’s ability in delineation, and it is the standard in multiple ongoing external-beam APBI trials. However, questions about the accuracy of the clips to mark the lumpectomy cavity remain, as clips only define a few points at the margin of the cavity. This paper reviews the techniques that have been developed so far to improve target delineation in APBI delivered by conformal external beam radiation therapy, including the use of standardized guidelines, surgical clips or fiducial markers, pre-operative computed tomography imaging, and additional imaging modalities, including magnetic resonance imaging, ultrasound imaging, and positron emission tomography/computed tomography. Alternatives to post-operative APBI, future directions, and clinical recommendations were also discussed.     

Update on accelerated partial-breast irradiation

Progress in radiotherapy technology, particularly the advent of CT-guided simulation and three-dimensional conformal planning, has given the radiation oncologist the ability to precisely treat part of the breast, instead of the whole breast, using either brachytherapy or external-beam techniques. Treating such a limited area may allow the course of treatment for patients with earlystage breast cancer to be drastically shortened and could reduce toxicity to other organs. This article summarizes the rationale for accelerated partial-breast irradiation (APBI), techniques for performing it, and outcome to date of studies of APBI.     

早期乳腺癌保乳术后4种放疗技术的剂量参数比较

目的：比较早期乳腺癌保乳术后常规切线野（TW）、野中野调强（FIF - IMRT）、切线逆向调强（T -IMRT）和容积调强（VMAT）4种放射治疗技术的靶区和危及器官的剂量参数。方法：15例左侧早期（pT1-2 N0 M0）乳腺癌患者保乳术后接受放疗。CT 模拟定位扫描后勾画靶区和危及器官,在同一患者 CT 影像上分别做 TW、FIF - IMRT、T - IMRT 和 VMAT 4种治疗计划设计。PTV 剂量为50Gy,V47.5≥95%。4种计划的剂量限制相同。在剂量-体积直方图中读取4种计划靶区剂量的分布参数,心脏、双侧肺脏及对侧乳腺受照剂量和体积,对各参数的均数进行比较,并比较4组平均机器跳数差异。结果：4种计划都满足 V47.5≥95%。VMAT 与 T - IMRT、FIF - IMRT 和 TW 计划相比,明显提高了靶区适行指数（CI,P ﹤0.05）。VMAT、T - IMRT和 FIF - IMRT 与 TW 相比,明显改善了靶区均匀性指数（HI,P ﹤0.05）。VMAT 增加了危及器官（心脏和同侧肺脏）V 5、V10和 V20的受照射体积,但是没有增加﹥ V30的照射体积。VMAT 明显增加了右侧乳腺和右侧肺脏照射剂量（P ﹤0.05）,T - IMRT 和 FIF - IMRT 明显降低了右侧乳腺和右侧肺脏照射剂量（P ﹤0.05）。VMAT 与T - IMRT、FIF - IMRT 和 TW 相比,明显增加了机器跳数（P ﹤0.05）。结论：早期乳腺癌保乳术后放射治疗4种计划比较,VMAT 明显提高了靶区的适行性和均匀性,增加了正常组织的受照射剂量和机器跳数,延长了治疗时间。T - IMRT 和 FIF - IMRT 也提高了靶区的适行性和均匀性,降低了正常组织的受照射剂量。     

Five-field IMRT class solutions and dosimetric planning guidelines for implementing accelerated partial breast irradiation

Purpose

A comprehensive set of planning guidelines was developed to aid in achieving reproducible dosimetric results for external beam accelerated partial breast irradiation (APBI). The methodology for the development of class solutions for dosimetric planning of the APBI technique, including dose constraint recommendations, is presented for target coverage and conformity as well as normal tissues.

Workshop on partial breast irradiation: state of the art and the science, Bethesda, MD, December 8-10, 2002

Breast conserving surgery followed by radiation therapy has been accepted as an alternative to mastectomy in the management of patients with early-stage breast cancer. Over the past decade there has been increasing interest in a variety of radiation techniques designed to treat only the portion of the breast deemed to be at high risk for local recurrence (partial-breast irradiation [PBI]) and to shorten the duration of treatment (accelerated partial-breast irradiation [APBI]). To consider issues regarding the equivalency of the various radiation therapy approaches and to address future needs for research, quality assurance, and training, the National Cancer Institute, Division of Cancer Treatment and Diagnosis, Radiation Research Program, hosted a Workshop on PBI in December 2002. Although 5- to 7-year outcome data on patients treated with PBI and APBI are now becoming available, many issues remain unresolved, including clinical and pathologic selection criteria, radiation dose and fractionation and how they relate to the standard fractionation for whole breast irradiation, appropriate target volume, local control within the untreated ipsilateral breast tissue, and overall survival. This Workshop report defines the issues in relation to PBI and APBI, recommends parameters for consideration in clinical trials and for reporting of results, serves to enhance dialogue among the advocates of the various radiation techniques, and emphasizes the importance of education and training in regard to results of PBI and APBI as they become emerging clinical treatments.     

直肠癌放射治疗方案剂量学比较

目的：研究直肠癌不同放射治疗计划的剂量学差异。方法：对18例直肠癌患者分别设计三维适形（3DCRT）和调强放射治疗计划（IMRT）,利用剂量体积直方图来比较2种计划中靶区、危机器官的剂量学差异。结果：IMRT与3DCRT相比,靶区适合度指数（CI）、靶区剂量不均匀性指数（HI）均更接近1,Dmean也更接近处方剂量,差异有统计学意义（P〈0.05）;与3 DCRT相比,IMRT中小肠的D30%、Dmean、Dmax,膀胱的D30%、D50%、Dmean更低;IMRT中小肠的D50%,股骨头的D5%、Dmean比3DCRT高,但仍远低于剂量限值。结论：IMRT技术对直肠癌进行治疗时,靶区适合度和靶区剂量均匀性更好,危及器官受量能够得到很好的控制。     

Hybrid IMRT plans--concurrently treating conventional and IMRT beams for improved breast irradiation and reduced planning time

PURPOSE: To evaluate a hybrid intensity modulated radiation therapy (IMRT) technique as a class solution for treatment of the intact breast. METHODS AND MATERIALS: The following five plan techniques were compared for 10 breast patients using dose-volume histogram analysis: conventional wedged-field tangents (Tangents), forward-planned field-within-a-field tangents (FIF), IMRT-only tangents (IMRT tangents), conventional open plus IMRT tangents (4-field hybrid), and conventional open plus IMRT tangents with 2 anterior oblique IMRT beams (6-field hybrid). RESULTS: The 4-field hybrid and FIF achieved dose distributions better than Tangents and IMRT tangents. The volume of tissue outside the planning target volume receiving > or =110% of prescribed dose was largest for IMRT tangents (average 158 cc) and least for 6-field hybrid (average 1 cc); the FIF and 4-field hybrid were comparable (average 15 cc). Heart volume > or =30 Gy averaged 13 cc for all techniques, except Tangents, for which it was 32 cc. Average total lung volume > or =20 Gy was 7% for all. Contralateral breast doses were < 3% for all. Planning time for hybrid techniques was significantly less than for conventional FIF technique. CONCLUSIONS: The 4-field hybrid technique is a viable class solution. The 6-field hybrid technique creates the most conformal dose distribution at the expense of more normal tissue receiving low dose.     

A dosimetric comparison between 3D-conformal radiation therapy and intensity modulated radiation therapy plans in the treatment of posterior fossa boost in children with high risk medulloblastom

Objective:The work is a comparative study between two modalities of radiation therapy, the aim of which is to compare 3D conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) in treating posterior fossa boost in children with high risk medul oblastoma;dosimetrical y evaluating and comparing both techniques as regard target coverage and doses to organs at risk (OAR). Methods:Twenty patients with high risk medul oblastoma were treated by 3D-CRT technique. A dosimetric comparison was done by performing two plans for the posterior fossa boost, 3D-CRT and IMRT plans, for the same patient using Eclipse planning system (version 8.6). Results:IMRT had a better conformity index compared to 3D-CRT plans (P value of 0.000). As for the dose homogeneity it was also better in the IMRT plans, yet it hasn’t reached the statistical significant value. Also, doses received by the cochleae, brainstem and spinal cord were significantly less in the IMRT plans than those of 3D-CRT (P value<0.05). Conclusion:IMRT technique was clearly able to improve conformity and homogeneity index, spare the cochleae, reduce dose to the brainstem and spinal cord in comparison to 3D-CRT technique.     

Feasibility of accelerated partial breast irradiation using three-dimensional conformal radiation therapy for Japanese women: a theoretical plan using six patients’ CT data

Background Several methods have been reported for accelerated partial breast irradiation (APBI), but in Japan, there are few facilities where brachytherapy or intra-operative radiotherapy is available. Japanese women have smaller physiques than American women in general. Thus, we developed external beam plans for APBI using computed tomography (CT) data of Japanese patients, to investigate whether APBI using three-dimensional conformal radiation therapy is safely applicable for Japanese women, while verifying the dose distributions. Methods We used CT data from six Japanese patients with early breast cancer, which were obtained in routine clinical practice during whole breast irradiation (WBI) after wide excision, and made 32 APBI plans according to the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-39 and the Radiation Therapy Oncology Group (RTOG) 0413 protocol, which compared APBI with WBI. We then investigated the compliance to the dose constraints of the protocol. Results None of 16 plans for the medial regions met the dose constraints regardless of laterality of the breast. The major reason was overdosage to the contralateral breast. Thirteen of 16 plans (81%) for the lateral regions met the dose constraints. The remaining three plans (19%) did not meet the dose limitation of the uninvolved normal breast, suggesting that a large ratio of the target to the breast was problematic. Conclusions In Japanese women, patients with a laterally located small tumor can be candidates for APBI using three-dimensional conformal radiation therapy.