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Yoo S, Blitzblau R, Yin FF, Horton JK. Dosimetric comparison of preoperative single-fraction partial breast radiotherapy techniques: 3D CRT, noncoplanar IMRT, coplanar IMRT, and VMAT. J Appl Clin Med Phys 2015; 16:5126. [PMID: 25679170 PMCID: PMC4484297 DOI: 10.1120/jacmp.v16i1.5126] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 09/29/2014] [Accepted: 09/19/2014] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to compare dosimetric parameters of treatment plans among four techniques for preoperative single‐fraction partial breast radiotherapy in order to select an optimal treatment technique. The techniques evaluated were noncoplanar 3D conformal radiation therapy (3D CRT), noncoplanar intensity‐modulated radiation therapy (IMRTNC), coplanar IMRT (IMRTCO), and volumetric‐modulated arc therapy (VMAT). The planning CT scans of 16 patients in the prone position were used in this study, with the single‐fraction prescription doses of 15 Gy for the first eight patients and 18 Gy for the remaining eight patients. Six (6) MV photon beams were designed to avoid the heart and contralateral breast. Optimization for IMRT and VMAT was performed to reduce the dose to the skin and normal breast. All plans were normalized such that 100% of the prescribed dose covered greater than 95% of the clinical target volume (CTV) consisting of gross tumor volume (GTV) plus 1.5 cm margin. Mean homogeneity index (HI) was the lowest (1.05±0.02) for 3D CRT and the highest (1.11±0.04) for VMAT. Mean conformity index (CI) was the lowest (1.42±0.32) for IMRTNC and the highest (1.60±0.32) for VMAT. Mean of the maximum point dose to skin was the lowest (73.7±11.5%) for IMRTNC and the highest (86.5±6.68%) for 3D CRT. IMRTCO showed very similar HI, CI, and maximum skin dose to IMRTNC (differences<1%). The estimated mean treatment delivery time, excluding the time spent for patient positioning and imaging, was 7.0±1.0,8.3±1.1,9.7±1.0, and 11.0±1.5min for VMAT,IMRTCO,IMRTNC and 3D CRT, respectively. In comparison of all four techniques for preoperative single‐fraction partial breast radiotherapy, we can conclude that noncoplanar or coplanar IMRT were optimal in this study as IMRT plans provided homogeneous and conformal target coverage, skin sparing, and relatively short treatment delivery time. PACS numbers: 81.40.Wx, 87.55.D‐
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Affiliation(s)
- Sua Yoo
- Duke University Medical Center.
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Abstract
The investigational nature of partial breast irradiation (PBI) remains an area of controversy in the field of breast radiotherapy. While we have a long track record of conducting and strongly supporting the research in this area, we have chosen the more cautious approach of continuing to offer PBI only as part of a trial, open to selected breast cancer patients at low risk of local recurrence. This position reflects the fact that existing whole breast radiotherapy has revealed very successful in controlling local recurrences and it remains the safest choice for the patient. Our thinking has been reinforced by the recent data linking the prevention of recurrence to long term breast cancer survival: until more is known about PBI safety, its indiscriminate use may deprive some women from their best chance of fighting breast cancer. Considerations regarding the correct interpretation of the available evidence in view of the still limited duration of follow up and of the pattern of local recurrence of breast cancer sustain our position that PBI can be offered only in the context of a clinical trial. Unfortunately, more time and data are warranted for PBI to be legitimately recognized a standard radiotherapy approach in breast conservation therapy.
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Ng SK, Zygmanski P, Jeung A, Mostafavi H, Hesser J, Bellon JR, Wong JS, Lyatskaya Y. Optimal parameters for clinical implementation of breast cancer patient setup using Varian DTS software. J Appl Clin Med Phys 2012; 13:3752. [PMID: 22584175 PMCID: PMC5716556 DOI: 10.1120/jacmp.v13i3.3752] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 12/21/2011] [Accepted: 01/02/2012] [Indexed: 11/23/2022] Open
Abstract
Digital tomosynthesis (DTS) was evaluated as an alternative to cone‐beam computed tomography (CBCT) for patient setup. DTS is preferable when there are constraints with setup time, gantry‐couch clearance, and imaging dose using CBCT. This study characterizes DTS data acquisition and registration parameters for the setup of breast cancer patients using nonclinical Varian DTS software. DTS images were reconstructed from CBCT projections acquired on phantoms and patients with surgical clips in the target volume. A shift‐and‐add algorithm was used for DTS volume reconstructions, while automated cross‐correlation matches were performed within Varian DTS software. Triangulation on two short DTS arcs separated by various angular spread was done to improve 3D registration accuracy. Software performance was evaluated on two phantoms and ten breast cancer patients using the registration result as an accuracy measure; investigated parameters included arc lengths, arc orientations, angular separation between two arcs, reconstruction slice spacing, and number of arcs. The shifts determined from DTS‐to‐CT registration were compared to the shifts based on CBCT‐to‐CT registration. The difference between these shifts was used to evaluate the software accuracy. After findings were quantified, optimal parameters for the clinical use of DTS technique were determined. It was determined that at least two arcs were necessary for accurate 3D registration for patient setup. Registration accuracy of 2 mm was achieved when the reconstruction arc length was > 5° for clips with HU ≥ 1000°; larger arc length (≥ 8°) was required for very low HU clips. An optimal arc separation was found to be ≥ 20° and optimal arc length was 10°. Registration accuracy did not depend on DTS slice spacing. DTS image reconstruction took 10–30 seconds and registration took less than 20 seconds. The performance of Varian DTS software was found suitable for the accurate setup of breast cancer patients. Optimal data acquisition and registration parameters were determined. PACS numbers: 87.57.‐s, 87.57.nf, 87.57.nj
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Affiliation(s)
- Sook Kien Ng
- Department of Radiation Oncology, Brigham and Women's Hospital & Dana Faber Cancer Institute, Harvard Medical School, Boston, MA, USA.
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Interfractional target variations for partial breast irradiation. Int J Radiat Oncol Biol Phys 2011; 82:1594-604. [PMID: 21570200 DOI: 10.1016/j.ijrobp.2011.01.041] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 12/28/2010] [Accepted: 01/12/2011] [Indexed: 11/23/2022]
Abstract
PURPOSE In this work, we quantify the interfractional variations in the shape of the clinical target volume (CTV) by analyzing the daily CT data acquired during CT-guided partial breast irradiation (PBI) and compare the effectiveness of various repositioning alignment strategies considered to account for the variations. METHODS AND MATERIALS The daily CT data for 13 breast cancer patients treated with PBI in either prone (10 patients) or supine (3 patients) with daily kV CT guidance using CT on Rails (CTVision, Siemens, Malvern, PA) were analyzed. For approximately 25 points on the surface of the CTV, deformation vectors were calculated by means of deformable image registration and verified by visual inspection. These were used to calculate the distances along surface normals (DSN), which directly related to the required margin expansions for each point. The DSN values were determined for seven alignment methods based on volumetric imaging and also two-dimensional projections (portal imaging). RESULTS The margin expansion necessary to cover 99% of all points for all days was 2.7 mm when utilizing the alignment method based on deformation field data (the best alignment method). The center-of-mass based alignment yielded slightly worse results (a margin of 4.0 mm), and shifts obtained by operator placement (7.9 mm), two-dimensional-based methods (7.0-10.1 mm), and skin marks (13.9 mm) required even larger margin expansions. Target shrinkage was evident for most days by the negative values of DSN. Even with the best alignment, the range of DSN values could be as high as 7 mm, resulting in a large amount of normal tissue irradiation, unless adaptive replanning is employed. CONCLUSION The appropriate alignment method is important to minimize the margin requirement to cover the significant interfractional target deformations observed during PBI. The amount of normal tissue unnecessarily irradiated is still not insignificant, and can be minimized if adaptive radiotherapy is applied.
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Zhao X, Wong EK, Wang Y, Lymberis S, Wen B, Formenti S, Chang J. A support vector machine (SVM) for predicting preferred treatment position in radiotherapy of patients with breast cancer. Med Phys 2010; 37:5341-50. [DOI: 10.1118/1.3483264] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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De Jean P, Beaulieu L, Fenster A. Three-dimensional ultrasound system for guided breast brachytherapy. Med Phys 2009; 36:5099-106. [DOI: 10.1118/1.3243865] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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MRI Guidance for Accelerated Partial Breast Irradiation in Prone Position: Imaging Protocol Design and Evaluation. Int J Radiat Oncol Biol Phys 2009; 75:285-93. [DOI: 10.1016/j.ijrobp.2009.03.063] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Revised: 01/08/2009] [Accepted: 03/24/2009] [Indexed: 11/20/2022]
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Buehler A, Ng SK, Lyatskaya Y, Stsepankou D, Hesser J, Zygmanski P. Evaluation of clip localization for different kilovoltage imaging modalities as applied to partial breast irradiation setup. Med Phys 2009; 36:821-34. [PMID: 19378743 DOI: 10.1118/1.3075904] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Surgical clip localization and image quality were evaluated for different types of kilovoltage cone beam imaging modalities as applied to partial breast irradiation (PBI) setup. These modalities included (i) clinically available radiographs and cone beam CT (CB-CT) and (ii) various alternative modalities based on partial/sparse/truncated CB-CT. An anthropomorphic torso-breast phantom with surgical clips was used for the imaging studies. The torso phantom had artificial lungs, and the attached breast phantom was a mammographic phantom with realistic shape and tissue inhomogeneities. Three types of clips of variable size were used in two orthogonal orientations to assess their in-/cross-plane characteristics for image-guided setup of the torso-breast phantom in supine position. All studies were performed with the Varian on-board imaging (OBI, Varian) system. CT reconstructions were calculated with the standard Feldkamp-Davis-Kress algorithm. First, the radiographs were studied for a wide range of viewing angles to characterize image quality for various types of body anatomy in the foreground/background of the clips. Next, image reconstruction quality was evaluated for partial/sparse/truncated CB-CT. Since these modalities led to reconstructions with strong artifacts due to insufficient input data, a knowledge-based CT reconstruction method was also tested. In this method, the input data to the reconstruction algorithm were modified by combining complementary data sets selected from the treatment and reference projections. Different partial/sparse/truncated CB-CT scan types were studied depending on the total are angle, angular increment between the consequent views (CT projections), orientation of the arc center with respect to the imaged breast and chest wall, and imaging field size. The central angles of the viewing arcs were either tangential or orthogonal to the chest wall. Several offset positions of the phantom with respect to the reference position were studied. The acquired and reconstructed image data sets were analyzed using home-built software focusing on the ability to localize clips in 3D. Streaking and leakage reconstruction artifacts and spatial distortions of breast surface were analyzed as well. Advantages and disadvantages of each kilovoltage CB imaging modality as applied to partial breast setup evaluation based on clips are presented. Because clips were found to be difficult to recognize in radiographs, 3D reconstructions were preferred. Even though it was possible to localize clips with about +/-1 mm accuracy based on reconstructions for short arcs of 40 degrees and incremental angle up to about 5 degrees, identification of clips in such reconstructions is difficult. Reconstructions obtained for arcs of as low as 80 degrees and incremental angle of as high as 3 degrees were suggested for easier clip identification. For more severely undersampled data, iterative CB-CT reconstruction is recommended to decrease the artifacts.
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Affiliation(s)
- Andreas Buehler
- University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer Ufer 1-3, D-68167 Mannheim, Germany
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Winey B, Zygmanski P, Lyatskaya Y. Evaluation of radiation dose delivered by cone beam CT and tomosynthesis employed for setup of external breast irradiation. Med Phys 2008; 36:164-73. [DOI: 10.1118/1.3036113] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Coverage of axillary lymph nodes in supine vs. prone breast radiotherapy. Int J Radiat Oncol Biol Phys 2008; 73:745-51. [PMID: 18687534 DOI: 10.1016/j.ijrobp.2008.04.040] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Revised: 04/24/2008] [Accepted: 04/29/2008] [Indexed: 11/22/2022]
Abstract
PURPOSE To compare the dosimetry of target and normal tissue when tangents with the breast tissue were applied in a subset of breast cancer patients who had undergone computed tomography (CT) planning both supine and prone. METHODS AND MATERIALS The CT images of 20 patients who had undergone simulation in supine and prone positions were used for planning. The axillary lymph node regions (level I-III), breast tissue, tumor bed, heart, and bilateral lungs were manually contoured. Standard tangent fields were designed for the whole breast to deliver a prescribed dose of 50 Gy. Dose-volume histograms were compared between the two sets. RESULTS In each patient, coverage of breast tissue and tumor bed was readily achieved by either technique. In either position, treatment of the nodal regions was inadequate. On average, the mean dose to the nodal regions for levels I-III was approximately 50% less in the prone as compared with the supine position. The mean ipsilateral lung volume receiving 95% of the prescribed dose was 6.3% in the supine position compared to 0.43% in the prone position. When planned supine, the mean heart volume receiving 30 Gy was 0.56% compared with 0.30% in the prone position. CONCLUSIONS Planning in either position was found to achieve adequate coverage of the breast tissue and tumor bed for all patients. Lung was better spared prone. Coverage of axillary nodes was inadequate in either position, but further reduced in the prone vs. supine position. The choice of optimal setup should take into considerations stage and risk of nodal recurrence.
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Formenti SC, Wernicke AG, DeWyngaert JK. External beam partial-breast radiotherapy: Crucial differences between NYU 00-23 and RTOG 0319: In regard to Vicini et al. (Int J Radiat Oncol Biol Phys 2005;63:1531–1537). Int J Radiat Oncol Biol Phys 2006; 66:630; author reply 630-1. [PMID: 16966007 DOI: 10.1016/j.ijrobp.2006.05.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Accepted: 05/11/2006] [Indexed: 11/30/2022]
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Accelerated partial breast irradiation: 3-dimensional conformal external beam radiotherapy. ACTA ACUST UNITED AC 2006. [DOI: 10.1017/s1470903105003639] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Dirbas FM, Jeffrey SS, Goffinet DR. The evolution of accelerated, partial breast irradiation as a potential treatment option for women with newly diagnosed breast cancer considering breast conservation. Cancer Biother Radiopharm 2005; 19:673-705. [PMID: 15665616 DOI: 10.1089/cbr.2004.19.673] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Breast conservation therapy (BCT) is a safe, effective alternative to mastectomy for many women with newly diagnosed breast cancer. This approach involves local excision of the malignancy with tumor-free margins, followed by 5-7 weeks of external beam whole breast (WB) radiotherapy (XRT) to minimize the risk of an in-breast tumor recurrence (IBTR). Though clearly beneficial, the extended course of almost daily postoperative radiotherapy interrupts normal activities and lengthens care. Additional options are now available that shorten the radiotherapy treatment time to 1-5 days (accelerated) and focus an increased dose of radiation on just the breast tissue around the excision cavity (partial breast). Recent trials with accelerated, partial breast irradiation (APBI) have shown promise as a potential replacement to the longer, whole breast treatments for select women with early-stage breast cancer. Current APBI approaches include interstitial brachytherapy, intracavitary (balloon) brachytherapy, and accelerated external beam (3-D conformal) radiotherapy, all of which normally complete treatment over 5 days, while intraoperative radiotherapy (IORT) condenses the entire treatment into a single dose delivered immediately after tumor excision. Each approach has benefits and limitations. This study covers over 2 decades of clinical trials exploring APBI, discusses treatment variables that appear necessary for successful implementation of this new form of radiotherapy, compares and contrasts the various APBI approaches, and summarizes current and planned randomized trials that will shape if and how APBI is introduced into routine clinical care. Some of the more important outcome variables from these trials will be local toxicity, local and regional recurrence, and overall survival. If APBI options are ultimately demonstrated to be as safe and effective as current whole breast radiotherapy approaches, breast conservation may become an even more appealing choice, and the overall impact of treatment may be further reduced for certain women with newly diagnosed breast cancer.
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Affiliation(s)
- Frederick M Dirbas
- Division of General Surgery, Department of Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA.
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Abstract
Although most studies treating patients with partial-breast irradiation have used brachytherapy, giving such treatment with external-beam techniques has many potential advantages. However, there is only limited published experience using this approach. These include a randomized trial of partial-breast and whole-breast irradiation performed at the Christie Hospital in Manchester, England, and pilot studies (using much more rigorous selection criteria and sophisticated treatment planning) from groups at the University of Southern California, New York University (using prone positioning of patients), and the William Beaumont Hospital (using the supine position). A multi-institutional pilot trial based on the latter technique has been completed, which was designed to test the feasibility of using this approach in the cooperative oncology group setting. The unprecedented rapidity with which the study completed its target accrual indicates the degree of interest in this approach. This review focuses on the rationale and the reported studies of external-beam partial-breast radiation and identifies some specific issues and remaining problems associated with this approach.
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Affiliation(s)
- Silvia C Formenti
- Departmetn of Radiation Oncology, New York University School of Medicine, New York, NY, USA.
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Rosenstein BS, Lymberis SC, Formenti SC. Biologic comparison of partial breast irradiation protocols. Int J Radiat Oncol Biol Phys 2004; 60:1393-404. [PMID: 15590170 DOI: 10.1016/j.ijrobp.2004.05.072] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Accepted: 05/28/2004] [Indexed: 11/18/2022]
Abstract
PURPOSE To analyze the dose/fractionation schedules currently used in ongoing clinical trials of partial breast irradiation (PBI) by comparing their biologically effective dose (BED) values to those of three standard whole breast protocols commonly used after segmental mastectomy in the treatment of breast cancer. METHODS AND MATERIALS The BED equation derived from the linear-quadratic model for radiation-induced cell killing was used to calculate the BEDs for three commonly used whole breast radiotherapy regimens, in addition to a variety of external beam radiotherapy, as well as high-dose-rate and low-dose-rate brachytherapy, PBI protocols. RESULTS The BED values of most PBI protocols resulted in tumor control BEDs roughly equivalent to a 50-Gy standard treatment, but consistently lower than the BEDs for regimens in which the tumor bed receives a total dose of either 60 Gy or 66 Gy. The BED values calculated for the acute radiation responses of erythema and desquamation were nearly all lower for the PBI schedules, and the late-response BEDs for most PBI regimens were in a similar range to the BEDs for the standard treatments. CONCLUSION Biologically effective dose modeling raises the concern that inadequate doses might be delivered by PBI to ensure optimal in-field tumor control.
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Affiliation(s)
- Barry S Rosenstein
- Department of Radiation Oncology, Mount Sinai School of Medicine, New York, NY 10029, USA.
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Formenti SC, Truong MT, Goldberg JD, Mukhi V, Rosenstein B, Roses D, Shapiro R, Guth A, Dewyngaert JK. Prone accelerated partial breast irradiation after breast-conserving surgery: preliminary clinical results and dose-volume histogram analysis. Int J Radiat Oncol Biol Phys 2004; 60:493-504. [PMID: 15380584 DOI: 10.1016/j.ijrobp.2004.04.036] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Revised: 04/13/2004] [Accepted: 04/13/2004] [Indexed: 11/18/2022]
Abstract
PURPOSE To report the clinical and dose-volume histogram results of the first 47 patients accrued to a protocol of accelerated partial breast irradiation. Patients were treated in the prone position with three-dimensional conformal radiotherapy after breast-conserving surgery. METHODS AND MATERIALS Postmenopausal women with Stage T1N0 breast cancer were eligible only after they had first refused to undergo 6 weeks of standard radiotherapy. Planning CT in the prone position was performed on a dedicated table. The postoperative cavity was defined as the clinical target volume, with a 1.5-cm margin added to determine the planning target volume. A total dose of 30 Gy at 6 Gy/fraction was delivered in five fractions within 10 days. RESULTS The median age of the patients was 67.5 years (range, 51-88 years). The median tumor diameter was 9 mm (range, 1.3-19 mm). In all patients, the prescribed dose encompassed the planning target volume. The mean volume of the ipsilateral breast receiving 100% of the prescription dose was 26% (range, 10-45%), and the mean volume contained within the 50% isodose surface was 47% (range, 23-75%). The lung and heart were spared by treating in the prone position. Acute toxicity was modest, limited mainly to Grade 1-2 erythema. With a median follow-up of 18 months, only Grade 1 late toxicity occurred, and no patient developed local recurrence. CONCLUSION These data suggest that this approach is well tolerated, with only mild acute side effects and sparing of the heart and lung.
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Affiliation(s)
- Silvia C Formenti
- Department of Radiation Oncology, New York University School of Medicine, New York, New York, USA.
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Truong MT, Hirsch AE, Formenti SC. Novel approaches to postoperative radiation therapy as part of breast-conserving therapy for early-stage breast cancer. Clin Breast Cancer 2004; 4:253-63. [PMID: 14651770 DOI: 10.3816/cbc.2003.n.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Breast-conserving therapy (BCT) consists of segmental mastectomy followed by postoperative radiation therapy (RT) to the whole breast. At least 6 prospective randomized trials have proven the equivalence of BCT to mastectomy. However, BCT remains underused and, most importantly, a sizable proportion of patients with invasive breast cancer fail to complete the recommended protocol of breast preservation by omitting postoperative RT. The inconvenience of complying with the standard 6-week radiation regimen, which includes approximately 30 daily visits, at least partially explains this lack of adherence. New clinical studies have generated preliminary evidence that more convenient, shorter radiation regimens might reveal equivalence to the current standard. Moreover, the availability of modern technology to deliver and target ionizing radiation by improving homogeneity of radiation dose has made it possible to safely explore the use of greater radiation doses per fraction. Finally, currently ongoing research trials will enable the identification of specific subsets of patients who are likely to be safely treated by partial-breast radiation (instead of radiation to the whole breast) with more accelerated regimens. This article reviews the available data and the current ongoing research on novel RT techniques and fractionation schedules in BCT for early-stage breast cancer.
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Affiliation(s)
- Minh Tam Truong
- Department of Radiation Oncology, New York University School of Medicine, New York, NY 10013, USA
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Abstract
PURPOSE Radiation source anisotropy causes about 10% of a spherically shaped planning target volume surrounding a MammoSite balloon to receive less than the prescribed dose. The principal dose-limiting factor for MammoSite therapy is the dose to the overlying skin. Additional limiting factors potentially include the dose to portions of the heart and lung. The goal of optimization is to deliver the prescribed dose to as much of the planning target volume as possible while avoiding toxicity to adjacent organs. METHODS AND MATERIALS An experimental CT-based high-dose-rate brachytherapy treatment planning system was used to investigate optimization strategies for MammoSite treatment. This system implements a linear optimization of high-dose-rate dwell times on the basis of constraints assigned to points of interest and a set of potential dwell positions. RESULTS The cylindrical symmetry of the MammoSite catheter limits the optimization process to creating spherical, ellipsoidal, or egg-shaped isodose distributions whose major axis is oriented along the catheter axis. If the dose to a limiting structure, such as skin, is not an issue, the use of multiple dwell positions can compensate for source anisotropy and create a more spherical isodose surface enclosing the planning target volume compared with a single dwell position. When skin becomes a dose-limiting factor, the catheter axis orientation, source anisotropy, dwell position, and dwell weighting can be exploited to limit the skin dose while simultaneously preserving the prescribed dose to as much of the target volume as possible. CONCLUSION Optimization of MammoSite therapy using multiple dwell positions within the balloon is both possible and practical.
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Affiliation(s)
- Melvin A Astrahan
- Department of Radiation Oncology, University of Southern California Norris Cancer Hospital, Los Angeles, CA 90033, USA.
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Formenti SC, Rosenstein B, Skinner KA, Jozsef G. T1 stage breast cancer: adjuvant hypofractionated conformal radiation therapy to tumor bed in selected postmenopausal breast cancer patients--pilot feasibility study. Radiology 2002; 222:171-8. [PMID: 11756722 DOI: 10.1148/radiol.2221010769] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To explore the feasibility of a short course of hypofractionated conformal radiation therapy to the tumor bed as part of a breast preservation protocol in postmenopausal patients with nonpalpable pT1N0 stage breast cancer. MATERIALS AND METHODS The tumor bed was imaged at computed tomography (CT) in the prone position on a dedicated table. The same table and position were used for treatment with a 4-MV linear accelerator. The planning target volume was the tumor bed plus a 1-2-cm margin defined at postmastectomy CT. A regimen of five fractions was tested in this pilot dose study. Cosmesis was assessed by patients and physicians before treatment and 36 months after treatment. RESULTS Ten consecutive patients who were eligible for the study were assigned to one of three dose-per-fraction regimens; nine were treatable with the proposed technique on the basis of CT findings. Patients received five fractions over 10 days (total dose range, 25-30 Gy): Three received 5.0 Gy per fraction; four, 5.5 Gy; and two, 6.0 Gy. At minimum follow-up of 36 months (range, 36-53 months), all patients were alive and disease free with good to excellent cosmesis. CONCLUSION Hypofractionated conformal breast radiation therapy is feasible. Further studies are warranted.
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Affiliation(s)
- Silvia C Formenti
- Department of Radiation Oncology, New York University School of Medicine, 566 First Ave, New York, NY 10016, USA
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