Prone accelerated partial breast irradiation after breast-conserving surgery: preliminary clinical results and dose-volume histogram analysis

Predicting the risk of secondary lung malignancies associated with whole-breast radiation therapy

PURPOSE

The risk of secondary lung malignancy (SLM) is a significant concern for women treated with whole-breast radiation therapy after breast-conserving surgery for early-stage breast cancer. In this study, a biologically based secondary malignancy model was used to quantify the risk of secondary lung malignancies (SLMs) associated with several common methods of delivering whole-breast radiation therapy (RT).

METHODS AND MATERIALS

Both supine and prone computed tomography simulations of 15 women with early breast cancer were used to generate standard fractionated and hypofractionated whole-breast RT treatment plans for each patient. Dose-volume histograms (DVHs) of the ipsilateral breast and lung were calculated for each patient on each plan. A model of spontaneous and radiation-induced carcinogenesis was used to determine the relative risks of SLMs for the different treatment techniques.

RESULTS

A higher risk of SLMs was predicted for supine breast irradiation when compared with prone breast irradiation for both the standard fractionation and hypofractionation schedules (relative risk [RR] = 2.59, 95% confidence interval (CI) = 2.30-2.88, and RR = 2.68, 95% CI = 2.39-2.98, respectively). No difference in risk of SLMs was noted between standard fractionation and hypofractionation schedules in either the supine position (RR = 1.05, 95% CI = 0.97-1.14) or the prone position (RR = 1.01, 95% CI = 0.88-1.15).

CONCLUSIONS

Compared with supine whole-breast irradiation, prone breast irradiation is associated with a significantly lower predicted risk of secondary lung malignancy. In this modeling study, fractionation schedule did not have an impact on the risk of SLMs in women treated with whole-breast RT for early breast cancer.

Automated beam placement for breast radiotherapy using a support vector machine based algorithm

PURPOSE

To develop an automated beam placement technique for whole breast radiotherapy using tangential beams. We seek to find optimal parameters for tangential beams to cover the whole ipsilateral breast (WB) and minimize the dose to the organs at risk (OARs).

METHODS

A support vector machine (SVM) based method is proposed to determine the optimal posterior plane of the tangential beams. Relative significances of including/avoiding the volumes of interests are incorporated into the cost function of the SVM. After finding the optimal 3-D plane that separates the whole breast (WB) and the included clinical target volumes (CTVs) from the OARs, the gantry angle, collimator angle, and posterior jaw size of the tangential beams are derived from the separating plane equation. Dosimetric measures of the treatment plans determined by the automated method are compared with those obtained by applying manual beam placement by the physicians. The method can be further extended to use multileaf collimator (MLC) blocking by optimizing posterior MLC positions.

RESULTS

The plans for 36 patients (23 prone- and 13 supine-treated) with left breast cancer were analyzed. Our algorithm reduced the volume of the heart that receives >500 cGy dose (V5) from 2.7 to 1.7 cm(3) (p = 0.058) on average and the volume of the ipsilateral lung that receives >1000 cGy dose (V10) from 55.2 to 40.7 cm(3) (p = 0.0013). The dose coverage as measured by volume receiving >95% of the prescription dose (V95%) of the WB without a 5 mm superficial layer decreases by only 0.74% (p = 0.0002) and the V95% for the tumor bed with 1.5 cm margin remains unchanged.

CONCLUSIONS

This study has demonstrated the feasibility of using a SVM-based algorithm to determine optimal beam placement without a physician's intervention. The proposed method reduced the dose to OARs, especially for supine treated patients, without any relevant degradation of dose homogeneity and coverage in general.

Why is partial-breast irradiation still investigational

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.

[Conformal accelerated partial breast irradiation: state of the art]

Breast conserving treatment (breast conserving surgery followed by whole breast irradiation) has commonly been used in early breast cancer since many years. New radiation modalities have been recently developed in early breast cancers, particularly accelerated partial breast irradiation. Three-dimensional conformal accelerated partial breast irradiation is the most commonly used modality of radiotherapy. Other techniques are currently being developed, such as intensity-modulated radiotherapy, arctherapy, and tomotherapy. The present article reviews the indications, treatment modalities and side effects of accelerated partial breast irradiation.

Prone accelerated partial breast irradiation after breast-conserving surgery: five-year results of 100 patients

PURPOSE

To report the 5-year results of a prospective trial of three-dimensional conformal external beam radiotherapy (3D-CRT) to deliver accelerated partial breast irradiation in the prone position.

METHODS AND MATERIALS

Postmenopausal patients with Stage I breast cancer with nonpalpable tumors <2 cm, negative margins and negative nodes, positive hormone receptors, and no extensive intraductal component were eligible. The trial was offered only after eligible patients had refused to undergo standard whole-breast radiotherapy. Patients were simulated and treated on a dedicated table for prone setup. 3D-CRT was delivered at a dose of 30 Gy in five 6-Gy/day fractions over 10 days with port film verification at each treatment. Rates of ipsilateral breast failure, ipsilateral nodal failure, contralateral breast failure, and distant failure were estimated using the cumulative incidence method. Rates of disease-free, overall, and cancer-specific survival were recorded.

RESULTS

One hundred patients were enrolled in this institutional review board-approved prospective trial, one with bilateral breast cancer. One patient withdrew consent after simulation, and another patient elected to interrupt radiotherapy after receiving two treatments. Ninety-eight patients were evaluable for toxicity, and, in 1 case, both breasts were treated with partial breast irradiation. Median patient age was 68 years (range, 53-88 years); in 55% of patients the tumor size was <1 cm. All patients had hormone receptor-positive cancers: 87% of patients underwent adjuvant antihormone therapy. At a median follow-up of 64 months (range, 2-125 months), there was one local recurrence (1% ipsilateral breast failure) and one contralateral breast cancer (1% contralateral breast failure). There were no deaths due to breast cancer by 5 years. Grade 3 late toxicities occurred in 2 patients (one breast edema, one transient breast pain). Cosmesis was rated good/excellent in 89% of patients with at least 36 months follow-up.

CONCLUSIONS

Five-year efficacy and toxicity of 3D-CRT delivered in prone partial breast irradiation are comparable to other experiences with similar follow-up.

Dosimetric evaluation of 3Dconformal acceleratedpartial-breast irradiation vs. whole-breast irradiation: A comparative study

Background:

Conventional early breast cancer treatment consists of lumpectomy followed by whole-breast irradiation (WBI) therapy. Accelerated partial-breast irradiation (APBI) is also an approach to post-lumpectomy radiation for early breast cancer.

Aim:

The purpose of this study is to compare two different external-beam APBI techniques using three-dimensional (3D) conformal radiation therapy (3DCRT), with conventional whole-breast irradiation based on the radiation conformity index, dose homogeneity index, and dose to organs at risk.

Materials and Methods:

WBI treatment plans were compared with two different 3DCRT APBI plans for each of 15 patients (8 with right sided lesions, 7 with left sided lesions). The first APBI plan (APBI 1) used two small coplanar fields conformed to the planning target volume (PTV) using multileaf collimators (MLCs) and wedges, while the other APBI plan (APBI 2) used three non-coplanar fields conformed to the PTV using MLCs and wedges.

Results:

Both the APBI techniques improved the conformity index significantly over whole-breast tangents while maintaining dose homogeneity and not causing significant increase in dose to organs at risk.

Conclusion:

Both the 3DCRT APBI techniques are technically feasible and dosimetrically appealing,with better target coverage and relative sparing of normal critical organs

Prone whole-breast irradiation using three-dimensional conformal radiotherapy in women undergoing breast conservation for early disease yields high rates of excellent to good cosmetic outcomes in patients with large and/or pendulous breasts

PURPOSE

To report our institution's experience using prone positioning for three-dimensional conformal radiotherapy (3D-CRT) to deliver post-lumpectomy whole breast irradiation (WBI) in a cohort of women with large and/or pendulous breasts, to determine the rate of acute and late toxicities and, more specifically, cosmetic outcomes. We hypothesized that using 3D-CRT for WBI in the prone position would reduce or eliminate patient and breast size as negative prognostic indicators for toxicities associated with WBI.

METHODS AND MATERIALS

From 1998 to 2006, 110 cases were treated with prone WBI using 3D-CRT. The lumpectomy, breast target volumes, heart, and lung were contoured on all computed tomography scans. A dose of 45-50 Gy was prescribed to the breast volume using standard fractionation schemes. The planning goals were ≥95% of prescription to 95% of the breast volume, and 100% of boost dose to 95% of lumpectomy planning target volume. Toxicities and cosmesis were prospectively scored using the Common Terminology Criteria for Adverse Effects Version 3.0 and the Harvard Scale. The median follow-up was 40 months.

RESULTS

The median body mass index (BMI) was 33.6 kg/m(2), and median breast volume was 1396 cm(3). The worst toxicity encountered during radiation was Grade 3 dermatitis in 5% of our patient population. Moist desquamation occurred in 16% of patients, with only 2% of patients with moist desquamation outside the inframammary/axillary folds. Eleven percent of patients had Grade ≥2 late toxicities, including Grade 3 induration/fibrosis in 2%. Excellent to good cosmesis was achieved in 89%. Higher BMI was associated with moist desquamation and breast pain, but BMI and breast volume did not impact fibrosis or excellent to good cosmesis.

CONCLUSION

In patients with higher BMI and/or large-pendulous breasts, delivering prone WBI using 3D-CRT results in favorable toxicity profiles and high excellent to good cosmesis rates. Higher BMI was associated with moist desquamation, but prone positioning removed BMI and breast size as factors for poorer cosmetic outcomes. This series adds to the growing literature demonstrating that prone WBI may be advantageous in select patients.

Partial breast irradiation techniques in early breast cancer

Whole breast irradiation represents an integral part of combined breast-conserving treatment of early breast cancer. A new concept includes replacing traditionally fractionated whole breast postoperative radiotherapy by accelerated partial breast irradiation. The latter involves a variety of techniques and may be applied intraoperatively or shortly after the surgery. The intraoperative techniques include photon or electron external beam irradiation and interstitial high dose rate (HDR) brachytherapy, whereas the postoperative techniques comprise interstitial brachytherapy, be it HDR, pulse dose rate (PDR) or low dose rate (LDR), intracavitary brachytherapy and external beam radiotherapy using electrons, photons or protons. This article presents accelerated partial breast irradiation techniques, ongoing phase III trials evaluating their value and recommendations for clinical practice.

The role of a prone setup in breast radiation therapy

Most patients undergoing breast conservation therapy receive radiotherapy in the supine position. Historically, prone breast irradiation has been advocated for women with large pendulous breasts in order to decrease acute and late toxicities. With the advent of CT planning, the prone technique has become both feasible and reproducible. It was shown to be advantageous not only for women with larger breasts but in most patients since it consistently reduces, if not eliminates, the inclusion of heart and lung within the field. The prone setup has been accepted as the best localizing position for both MRI and stereotactic biopsy, but its adoption has been delayed in radiotherapy. New technological advances including image-modulated radiation therapy and image-guided radiation therapy have made possible the exploration of accelerated fractionation schemes with a concomitant boost to the tumor bed in the prone position, along with better imaging and verification of reproducibility of patient setup. This review describes some of the available techniques for prone breast radiotherapy and the available experience in their application. The NYU prone breast radiotherapy approach is discussed, including a summary of the results from several prospective trials.

Video surface image guidance for external beam partial breast irradiation

OBJECTIVE

Accelerated partial breast irradiation is an emerging treatment option for early stage breast cancer. With accelerated partial breast irradiation, patient setup, and target registration accuracy is vital. The current study compared various methods for isocenter placement accuracy.

METHODS AND MATERIALS

Twenty-three patients treated on an institutional-approved partial breast irradiation protocol were monitored at each treatment fraction. All patients included in this study underwent clip placement at the time of surgery. Patients underwent computed tomographic simulation and surface contours were used to reconstruct a reference surface map. At the treatment machine, patients were initially positioned by laser alignment to tattoos. Orthogonal kilovoltage imaging of the chest wall, followed by video surface mapping of the breast, was performed. This video surface map was matched to the reference surface map to adjust the couch position. Verification orthogonal chest wall imaging and video surface mapping was again performed. The accuracy of setup by laser, orthogonal imaging of the chest wall, and surface alignment was retrospectively compared using the centroid clip position as the reference standard. The impact of setup error by surface alignment and by orthogonal kilovoltage imaging on planning target volume coverage was then calculated.

RESULTS

Laser-based positioning resulted in a residual setup error of 3.9 ± 3.7 mm, 4.6 ± 3.9 mm, and 4.3 ± 4.5 mm in the posterior-anterior (P-A), inferior-superior (I-S), and left-right (L-R) directions, respectively, using clips as the reference standard. Setup based on bony anatomy with orthogonal imaging resulted in residual setup error of 3.2 ± 2.9 (P-A), 4.2 ± 3.5 (I-S), and 4.7 ± 5.3 mm (L-R). Setup with video surface mapping resulted in a residual setup error of 1.9 ± 2.2, 1.8 ± 1.9, and 1.8 ± 2.1 mm in the P-A, I-S, and L-R directions, respectively. Vector spatial deviation was 8.8 ± 4.2, 8.3 ± 3.8, and 4.0 ± 2.3 mm with laser, chest wall on board imaging, and video surface mapping based setup, respectively. Setup by video surface mapping resulted in improved dosimetric coverage of the planning target volume when compared with orthogonal imaging of the chest wall (V100 96.0% ± 0.1% vs 89.3% ± 0.2%; V95 99.7% ± 0.01% vs 98.6% ± 0.01%, P < .05).

CONCLUSIONS

Video surface mapping of the breast is a more accurate method for isocenter placement in comparison to conventional laser-based alignment or orthogonal kilovoltage imaging of the chest wall.

Impact of residual and intrafractional errors on strategy of correction for image-guided accelerated partial breast irradiation

BACKGROUND

The cone beam CT (CBCT) guided radiation can reduce the systematic and random setup errors as compared to the skin-mark setup. However, the residual and intrafractional (RAIF) errors are still unknown. The purpose of this paper is to investigate the magnitude of RAIF errors and correction action levels needed in cone beam computed tomography (CBCT) guided accelerated partial breast irradiation (APBI).

METHODS

Ten patients were enrolled in the prospective study of CBCT guided APBI. The postoperative tumor bed was irradiated with 38.5 Gy in 10 fractions over 5 days. Two cone-beam CT data sets were obtained with one before and one after the treatment delivery. The CBCT images were registered online to the planning CT images using the automatic algorithm followed by a fine manual adjustment. An action level of 3 mm, meaning that corrections were performed for translations exceeding 3 mm, was implemented in clinical treatments. Based on the acquired data, different correction action levels were simulated, and random RAIF errors, systematic RAIF errors and related margins before and after the treatments were determined for varying correction action levels.

RESULTS

A total of 75 pairs of CBCT data sets were analyzed. The systematic and random setup errors based on skin-mark setup prior to treatment delivery were 2.1 mm and 1.8 mm in the lateral (LR), 3.1 mm and 2.3 mm in the superior-inferior (SI), and 2.3 mm and 2.0 mm in the anterior-posterior (AP) directions. With the 3 mm correction action level, the systematic and random RAIF errors were 2.5 mm and 2.3 mm in the LR direction, 2.3 mm and 2.3 mm in the SI direction, and 2.3 mm and 2.2 mm in the AP direction after treatments delivery. Accordingly, the margins for correction action levels of 3 mm, 4 mm, 5 mm, 6 mm and no correction were 7.9 mm, 8.0 mm, 8.0 mm, 7.9 mm and 8.0 mm in the LR direction; 6.4 mm, 7.1 mm, 7.9 mm, 9.2 mm and 10.5 mm in the SI direction; 7.6 mm, 7.9 mm, 9.4 mm, 10.1 mm and 12.7 mm in the AP direction, respectively.

CONCLUSIONS

Residual and intrafractional errors can significantly affect the accuracy of image-guided APBI with nonplanar 3DCRT techniques. If a 10-mm CTV-PTV margin is applied, a correction action level of 5 mm or less is necessary so as to maintain the RAIF errors within 10 mm for more than 95% of fractions. Pre-treatment CBCT guidance is not a guarantee for safe delivery of the treatment despite its known benefits of reducing the initial setup errors. A patient position verification and correction during the treatment may be a method for the safe delivery.

Accelerated Partial Breast Irradiation (APBI): A review of available techniques

Breast conservation therapy (BCT) is the procedure of choice for the management of the early stage breast cancer. However, its utilization has not been maximized because of logistics issues associated with the protracted treatment involved with the radiation treatment. Accelerated Partial Breast Irradiation (APBI) is an approach that treats only the lumpectomy bed plus a 1-2 cm margin, rather than the whole breast. Hence because of the small volume of irradiation a higher dose can be delivered in a shorter period of time. There has been growing interest for APBI and various approaches have been developed under phase I-III clinical studies; these include multicatheter interstitial brachytherapy, balloon catheter brachytherapy, conformal external beam radiation therapy and intra-operative radiation therapy (IORT). Balloon-based brachytherapy approaches include Mammosite, Axxent electronic brachytherapy and Contura, Hybrid brachytherapy devices include SAVI and ClearPath. This paper reviews the different techniques, identifying the weaknesses and strength of each approach and proposes a direction for future research and development. It is evident that APBI will play a role in the management of a selected group of early breast cancer. However, the relative role of the different techniques is yet to be clearly identified.

Initial efficacy results of RTOG 0319: three-dimensional conformal radiation therapy (3D-CRT) confined to the region of the lumpectomy cavity for stage I/ II breast carcinoma

PURPOSE

This prospective study (Radiation Therapy Oncology Group 0319) examines the use of three-dimensional conformal external beam radiotherapy (3D-CRT) to deliver accelerated partial breast irradiation (APBI). Initial data on efficacy and toxicity are presented.

METHODS AND MATERIALS

Patients with Stage I or II breast cancer with lesions < or =3 cm, negative margins and with < or =3 positive nodes were eligible. The 3D-CRT was 38.5 Gy in 3.85 Gy/fraction delivered 2x/day. Ipsilateral breast, ipsilateral nodal, contralateral breast, and distant failure (IBF, INF, CBF, DF) were estimated using the cumulative incidence method. Mastectomy-free, disease-free, and overall survival (MFS, DFS, OS) were recorded. The National Cancer Institute Common Terminology Criteria for Adverse Events, version 3, was used to grade acute and late toxicity.

RESULTS

Fifty-eight patients were entered and 52 patients are eligible and evaluable for efficacy. The median age of patients was 61 years with the following characteristics: 46% tumor size <1 cm; 87% invasive ductal histology; 94% American Joint Committee on Cancer Stage I; 65% postmenopausal; 83% no chemotherapy; and 71% with no hormone therapy. Median follow-up is 4.5 years (1.7-4.8). Four-year estimates (95% CI) of efficacy are: IBF 6% (0-12%) [4% within field (0-9%)]; INF 2% (0-6%); CBF 0%; DF 8% (0-15%); MFS 90% (78-96%); DFS 84% (71-92%); and OS 96% (85-99%). Only two (4%) Grade 3 toxicities were observed.

CONCLUSIONS

Initial efficacy and toxicity using 3D-CRT to deliver APBI appears comparable to other experiences with similar follow-up. However, additional patients, further follow-up, and mature Phase III data are needed to evaluate the extent of application, limitations, and value of this particular form of APBI.

Accelerated Partial Breast Irradiation: Potential Roles following Breast-Conserving Surgery

Background

Multiple randomized trials comparing mastectomy to lumpectomy and whole breast irradiation (WBI) have shown equivalent survival outcomes in early-stage breast cancer. WBI requires a treatment course of several weeks, which has resulted in limited access to breast-conserving therapy in certain populations. A shorter accelerated course of partial breast irradiation (APBI) has been investigated recently.

Methods

This article reviews the current medical literature, including randomized trials and prospective institutional studies of APBI and the current recommendations regarding the use of this emerging technique.

Results

Several APBI techniques have been developed, including brachytherapy and external beam methods. The longest follow-up data are available for multicatheter interstitial brachytherapy, a technique that is not commonly used. Other methods, including balloon brachytherapy and external beam three-dimensional conformal techniques, have limited follow-up that shows similar local control rates to whole breast irradiation in highly selected patients. Guidelines for the appropriate use of APBI have been published.

Conclusions

While APBI may increase access to breast conservation therapy for some women with early-stage breast cancer, follow-up data demonstrating the efficacy of this relatively new treatment approach are limited. Therefore, strict evidence-based selection criteria should be applied when evaluating patients who may be appropriate for APBI.

Continuous arc rotation of the couch therapy for the delivery of accelerated partial breast irradiation: a treatment planning analysis

PURPOSE

We present a novel form of arc therapy: continuous arc rotation of the couch (C-ARC) and compare its dosimetry with three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT) for accelerated partial breast irradiation (APBI). C-ARC, like VMAT, uses a modulated beam aperture and dose rate, but with the couch, not the gantry, rotating.

METHODS AND MATERIALS

Twelve patients previously treated with APBI using 3D-CRT were replanned with (1) C-ARC, (2) IMRT, and (3) VMAT. C-ARC plans were designed with one medial and one lateral arc through which the couch rotated while the gantry was held stationary at a tangent angle. Target dose coverage was normalized to the 3D-CRT plan. Comparative endpoints were dose to normal breast tissue, lungs, and heart and monitor units prescribed.

RESULTS

Compared with 3D-CRT, C-ARC, IMRT, and VMAT all significantly reduced the ipsilateral breast V50% by the same amount (mean, 7.8%). Only C-ARC and IMRT plans significantly reduced the contralateral breast maximum dose, the ipsilateral lung V5Gy, and the heart V5%. C-ARC used on average 40%, 30%, and 10% fewer monitor units compared with 3D-CRT, IMRT, and VMAT, respectively.

CONCLUSIONS

C-ARC provides improved dosimetry and treatment efficiency, which should reduce the risks of toxicity and secondary malignancy. Its tangent geometry avoids irradiation of critical structures that is unavoidable using the en face geometry of VMAT.

Cosmetic outcomes for accelerated partial breast irradiation before surgical excision of early-stage breast cancer using single-dose intraoperative radiotherapy

PURPOSE

Determine cosmetic outcome and toxicity profile of intraoperative radiation delivered before tumor excision for patients with early-stage breast cancer.

METHODS AND MATERIALS

Patients age 48 or older with ultrasound-visible invasive ductal cancers <3 cm and clinically negative lymph nodes were eligible for treatment on this institutional review board-approved Phase II clinical trial. Treatment planning ultrasound was used to select an electron energy and cone size sufficient to cover the tumor plus a 1.5- to 2.0-cm circumferential margin laterally and a 1-cm-deep margin with the 90% isodose line. The dose was prescribed to a nominal 15 Gy and delivered using a Mobetron electron irradiator before tumor excision by segmental mastectomy. Physician- and patient-assessed cosmetic outcome and patient satisfaction were determined by questionnaire.

RESULTS

From March 2003 to July 2007, 71 patients were treated with intraoperative radiation therapy. Of those, 56 patients were evaluable, with a median follow-up of 3.1 years (minimum 1 year). Physician and patient assessment of cosmesis was "good or excellent" (Radiation Therapy Oncology Group cosmesis scale) in 45/56 (80%) and 32/42 (76%) of all patients, respectively. Eleven patients who received additional whole breast radiation had similar rates of good or excellent cosmesis: 40/48 (83%) and 29/36 (81%), respectively). Grade 1 or 2 acute toxicities were seen in 4/71 (6%) patients. No Grade 3 or 4 toxicities or serious adverse events have been seen.

CONCLUSION

Intraoperative radiotherapy delivered to an in situ tumor is feasible with acceptable acute tolerance. Patient and physician assessment of the cosmetic outcome is good to excellent.

Partial breast irradiation: a review of techniques and indications

The addition of whole-breast external beam radiotherapy (EBRT) to breast-conserving surgery results in a significant reduction in the risk of death due to breast cancer, but this may be offset by an increase in deaths from other causes and toxicity to surrounding organs. Because of this, and with a view to patterns of local recurrence, irradiation of the tumour bed has been explored in selected patients with early breast cancer using a variety of radiotherapeutic modalities. This review article explores the treatment options for partial breast irradiation and examines their role within the field of breast cancer treatment.

Unacceptable cosmesis in a protocol investigating intensity-modulated radiotherapy with active breathing control for accelerated partial-breast irradiation

PURPOSE

To report interim cosmetic results and toxicity from a prospective study evaluating accelerated partial-breast irradiation (APBI) administered using a highly conformal external beam approach.

METHODS AND MATERIALS

We enrolled breast cancer patients in an institutional review board-approved prospective study of APBI using beamlet intensity-modulated radiotherapy (IMRT) at deep-inspiration breath-hold. Patients received 38.5 Gy in 3.85 Gy fractions twice daily. Dosimetric parameters in patients who maintained acceptable cosmesis were compared with those in patients developing unacceptable cosmesis in follow-up, using t-tests.

RESULTS

Thirty-four patients were enrolled; 2 were excluded from analysis because of fair baseline cosmesis. With a median follow-up of 2.5 years, new unacceptable cosmesis developed in 7 patients, leading to early study closure. We compared patients with new unacceptable cosmesis with those with consistently acceptable cosmesis. Retrospective analysis demonstrated that all but one plan adhered to the dosimetric requirements of the national APBI trial. The mean proportion of a whole-breast reference volume receiving 19.25 Gy (V50) was lower in patients with acceptable cosmesis than in those with unacceptable cosmesis (34.6% vs. 46.1%; p = 0.02). The mean percentage of this reference volume receiving 38.5 Gy (V100) was also lower in patients with acceptable cosmesis (15.5% vs. 23.0%; p = 0.02).

CONCLUSIONS

The hypofractionated schedule and parameters commonly used for external beam APBI and prescribed by the ongoing national trial may be suboptimal, at least when highly conformal techniques such as IMRT with management of breathing motion are used. The V50 and V100 of the breast reference volume seem correlated with cosmetic outcome, and stricter limits may be appropriate in this setting.

3D-conformal accelerated partial breast irradiation treatment planning: the value of surgical clips in the delineation of the lumpectomy cavity

BACKGROUND

Accurate localisation of the lumpectomy cavity (LC) volume is one of the most critical points in 3D-conformal Partial breast irradiation (3D-APBI) treatment planning because the irradiated volume is restricted to a small breast volume. Here, we studied the role of the placement of surgical clips at the 4 cardinal points of the lumpectomy cavity in target delineation.

METHODS

Forty CT-based 3D-APBI plans were retrieved on which a total of 4 radiation oncologists, two trainee and two experienced physicians, outlined the lumpectomy cavity. The inter-observer variability of LC contouring was assessed when the CTV was defined as the delineation that encompassed both surgical clips and remodelled breast tissue.

RESULTS

The conformity index of tumour bed delineation was significantly improved by the placement of surgical clips within the LC (median at 0.65). Furthermore, a better conformity index of LC was observed according to the experience of the physicians (median CI = 0.55 for trainee physicians vs 0.65 for experienced physicians).

CONCLUSIONS

The placement of surgical clips improved the accuracy of lumpectomy cavity delineation in 3D-APBI. However, a learning curve is needed to improve the conformity index of the lumpectomy cavity.

Radiation techniques and toxicities for locally advanced breast cancer

Radiation therapy is used in the management of locally advanced breast cancer in the postmastectomy or neoadjuvant chemotherapy and breast-conservation setting to improve local-regional control and survival. Using modern-day technology, the therapeutic ratio has increased and the potential morbidity has decreased. This article reviews the technical aspects of radiation therapy for locally advanced breast cancer with emphasis on 3-dimensional radiotherapy techniques and discusses potential toxicities and how to reduce them.

Lung Dose-Volume Parameters and the Risk of Pneumonitis for Patients Treated With Accelerated Partial-Breast Irradiation Using Three-Dimensional Conformal Radiotherapy

Purpose

There are no data on how complication rates after accelerated partial-breast irradiation delivered by three-dimensional conformal radiotherapy are affected by treatment technique. We therefore examined the risk of pneumonitis in relation to lung dose-volume parameters.

Patients and Methods

Our prospective dose-escalation trial enrolled 198 treated patients from 2003 to 2007. Patients received 32 or 36 Gy in 4-Gy fractions, given twice daily: 29 (14%) were treated with pure photons; 149 (77%) with mixed photons and electrons; and 20 (10%) with protons.

Results

There were four cases of pneumonitis at 4, 4, 7, and 9 months after treatment. All were in the 36-Gy cohort and were treated with pure photons. The risk of pneumonitis for the two cohorts combined was: 17% (four of 24) for an ipsilateral lung volume (ILV) receiving 20 Gy or higher (ILV, 20 Gy) of 3% or higher (P = .0002 for comparison to ILV 20 Gy < 3%, Fisher's exact test); 20% (four of 20) for an ILV 10 Gy of 10% or higher (P = .0001); and 15% (four of 26) for an ILV 5 Gy of 20% or higher (P = .0002).

Conclusion

The risk of pneumonitis appeared related to the ILV treated. This volume can be reduced by using mixed photons and electron when possible. We recommend that the ILV 20 Gy should be lower than 3%, the ILV 10 Gy lower than 10%, and the ILV 5 Gy lower than 20% when purely coplanar techniques are used.

Accelerated partial breast irradiation consensus statement from the American Society for Radiation Oncology (ASTRO)

PURPOSE

To present guidance for patients and physicians regarding the use of accelerated partial-breast irradiation (APBI), based on current published evidence complemented by expert opinion.

METHODS AND MATERIALS

A systematic search of the National Library of Medicine's PubMed database yielded 645 candidate original research articles potentially applicable to APBI. Of these, 4 randomized trials and 38 prospective single-arm studies were identified. A Task Force composed of all authors synthesized the published evidence and, through a series of meetings, reached consensus regarding the recommendations contained herein.

RESULTS

The Task Force proposed three patient groups: (1) a "suitable" group, for whom APBI outside of a clinical trial is acceptable, (2) a "cautionary" group, for whom caution and concern should be applied when considering APBI outside of a clinical trial, and (3) an "unsuitable" group, for whom APBI outside of a clinical trial is not generally considered warranted. Patients who choose treatment with APBI should be informed that whole-breast irradiation (WBI) is an established treatment with a much longer track record that has documented long-term effectiveness and safety.

CONCLUSION

Accelerated partial-breast irradiation is a new technology that may ultimately demonstrate long-term effectiveness and safety comparable to that of WBI for selected patients with early breast cancer. This consensus statement is intended to provide guidance regarding the use of APBI outside of a clinical trial and to serve as a framework to promote additional clinical investigations into the optimal role of APBI in the treatment of breast cancer.

Accelerated partial breast irradiation: what is dosimetric effect of advanced technology approaches?

PURPOSE

The present treatment planning study compared whole breast radiotherapy (WBRT) to accelerated partial breast irradiation (APBI) for different external beam techniques and geometries (e.g., free breathing [FB] and deep inspiration breath hold [DIBH]).

METHODS AND MATERIALS

After approval by our institutional review board, a treatment planning study was performed of 10 patients with left-sided Stage 0-I breast cancer enrolled in a Phase I-II study of APBI using intensity-modulated radiotherapy (IMRT). After lumpectomy, patients underwent planning computed tomography scans during FB and using an active breathing control device at DIBH. For the FB geometry, standard WBRT and three-dimensional conformal radiotherapy (3D-CRT) APBI plans were created. For the DIBH geometry with active breathing control, WBRT, 3D-CRT, and IMRT APBI plans were created.

RESULTS

All APBI techniques had excellent planning target volume coverage. The maximal planning target volume dose was reduced from 116% of the prescription dose to 108% with the IMRT(DIBH) APBI plan. The maximal heart dose was >30 Gy for the WBRT techniques, 8.2 Gy for 3D-CRT(FB), and <5.0 Gy for 3D-CRT(DIBH) and IMRT(DIBH) techniques. The mean left anterior descending artery dose was significantly reduced from 11.4 Gy with WBRT(FB) to 4.2 with WBRT(DIBH) and <2.0 Gy with all APBI techniques.

CONCLUSION

Although planning target volume coverage was acceptable with all techniques, the plans using the DIBH geometry resulted in a marked reduction in the normal tissue dose compared with WBRT planned in the absence of cardiac blocking. Additional study is needed to determine whether these techniques result in clinical benefits.

Four-year efficacy, cosmesis, and toxicity using three-dimensional conformal external beam radiation therapy to deliver accelerated partial breast irradiation

PURPOSE

This prospective study examines the use of three-dimensional conformal external beam radiation therapy (3D-CRT) to deliver accelerated partial breast irradiation (APBI). Four-year data on efficacy, cosmesis, and toxicity are presented.

METHODS

Patients with Stage O, I, or II breast cancer with lesions </=3 cm, negative margins, and negative nodes were eligible. The 3D-CRT delivered was 38.5 Gy in 3.85 Gy/fraction. Ipsilateral breast, ipsilateral nodal, contralateral breast, and distant failure (IBF, INF, CBF, DF) were estimated using the cumulative incidence method. Disease-free, overall, and cancer-specific survival (DFS, OS, CSS) were recorded. The National Cancer Institute Common Terminology Criteria for Adverse Events (version 3) toxicity scale was used to grade acute and late toxicities.

RESULTS

Ninety-four patients are evaluable for efficacy. Median patient age was 62 years with the following characteristics: 68% tumor size <1 cm, 72% invasive ductal histology, 77% estrogen receptor (ER) (+), 88% postmenopausal; 88% no chemotherapy and 44% with no hormone therapy. Median follow-up was 4.2 years (range, 1.3-8.3). Four-year estimates of efficacy were IBF: 1.1% (one local recurrence); INF: 0%; CBF: 1.1%; DF: 3.9%; DFS: 95%; OS: 97%; and CSS: 99%. Four (4%) Grade 3 toxicities (one transient breast pain and three fibrosis) were observed. Cosmesis was rated good/excellent in 89% of patients at 4 years.

CONCLUSIONS

Four-year efficacy, cosmesis, and toxicity using 3D-CRT to deliver APBI appear comparable to other experiences with similar follow-up. However, additional patients, further follow-up, and mature Phase III data are needed to evaluate thoroughly the extent of application, limitations, and complete value of this particular form of APBI.