Surgical clips in planning the electron boost in breast cancer: a qualitative and quantitative evaluation

Master Breast Radiation Planning: Simple Guide for Radiation Oncology Residents

This article focuses on various aspects of breast radiation treatment planning, from simulation to field design. It covers the most common techniques including tangents, mono isocentric, dual isocentric, electron-photon match, and VMAT. This can serve as a guide for radiation oncology residents and medical students to advance their understanding of key aspects of breast radiation treatment and planning processes.

Stabilised Hyaluronic Acid (sHA) gel as a novel marker for breast cancer tumour bed cavity: Surgical feasibility

Introduction

Consistent delineation of the breast conserving surgery (BCS) tumour bed (TB) for breast cancer remains a challenge for radiation oncologists. Accurate delineation allows for better local control and reduces toxicity when planning partial breast or TB boost radiation therapy (RT).

Methods

In the operating theatre (OT) breast surgeons inserted stabilised hyaluronic acid (sHA) gel as small drops approximately one cm into the walls surrounding the resection cavity. Surgical feasibility was determined by the rate of successful sHA gel insertion procedure, the ease of insertion as rated by surgeons, the time required for insertion procedure, the quantity used, and any adverse events (AE) relating to sHA gel insertion.

Results

Thirty-five patients were enrolled. All patients underwent sHA gel insertion successfully. The procedure added a median of 2.8 min to the OT time and was rated as 'easy' in 89 % of patients. There were no immediate AE in OT. Five (14 %) patients experienced a grade 2 or higher AE. Three of the five patients were prescribed oral antibiotics for breast infection. Two of the five patients experienced a grade 3 AE - haematoma which required evacuation in OT day 1 post-BCS, and infected seroma which required drainage and washout in OT 2 months post-BCS. All five patients recovered and underwent the planned adjuvant therapies for their BC. The AE data reflects common risks with standard BCS and are not clearly attributed to sHA gel insertion alone.

Conclusion

We show that sHA gel is surgically feasible as a marker to help define the TB cavity for post-BCS adjuvant MRI-based RT planning.

Comparison of Tumor Bed Delineation Using a Novel Radiopaque Filament Marker Versus Surgical Clips for Targeting Breast Cancer Radiotherapy

BACKGROUND

Accuracy of tumor bed (TB) delineation is essential for targeting boost doses or partial breast irradiation. Multiple studies have shown high interobserver variability with standardly used surgical clip markers (CMs). We hypothesize that a radiopaque filament marker (FM) woven along the TB will improve TB delineation consistency.

METHODS

An FDA-approved FM was intraoperatively used to outline the TB of patients undergoing lumpectomy. Between January 2020 and January 2022, consecutive patients with FM placed after either (1) lumpectomy or (2) lumpectomy with oncoplastic reconstruction were identified and compared with those with CM. Six "experts" (radiation oncologists specializing in breast cancer) across 2 institutions independently defined all TBs. Three metrics (volume variance, dice coefficient, and center of mass [COM] deviation). Two-tailed paired samples t tests were performed to compare FM and CM cohorts.

RESULTS

Twenty-eight total patients were evaluated (14 FM and 14 CM). In aggregate, differences in volume between expert contours were 29.7% (SD ± 58.8%) with FM and 55.4% (SD ± 105.9%) with CM ( P < 0.001). The average dice coefficient in patients with FM was 0.54 (SD ± 0.15), and with CM was 0.44 (SD ± 0.22) ( P < 0.001). The average COM deviation was 0.63 cm (SD ± 0.53 cm) for FM and 1.05 cm (SD ± 0.93 cm) for CM; ( P < 0.001). In the subset of patients who underwent lumpectomy with oncoplastic reconstruction, the difference in average volume was 21.8% (SD ± 20.4%) with FM and 52.2% (SD ± 64.5%) with CM ( P <0.001). The average dice coefficient was 0.53 (SD ± 0.12) for FM versus 0.39 (SD ± 0.24) for CM ( P < 0.001). The average COM difference was 0.53 cm (SD ± 0.29 cm) with FM versus 1.25 cm (SD ± 1.08 cm) with CM ( P < 0.001).

CONCLUSION

FM consistently outperformed CM in the setting of both standard lumpectomy and complex oncoplastic reconstruction. These data suggest the superiority of FM in TB delineation.

The role of the radiation therapy breast boost in the 2020s

Given that most local relapses of breast cancer occur proximal to the original location of the primary, the delivery of additional radiation dose to breast tissue that contained the original primary cancer (known as a "boost") has been a standard of care for some decades. In the context of falling relapse rates, however, it is an appropriate time to re-evaluate the role of the boost. This article reviews the evolution of the radiotherapy boost in breast cancer, discussing who to boost and how to boost in the 2020s, and arguing that, in both cases, less is more.

Quality assurance program and early toxicities in the phase III BONBIS randomized trial evaluating the role of a localized radiation boost in ductal carcinoma in situ

PURPOSE

To describe the quality assurance (QA) program and early toxicities in the phase III randomized trial BONBIS (NCT00907868) on the role of a localized radiation boost in ductal carcinoma in situ (DCIS).

MATERIALS AND METHODS

From November 2008 to July 2014, 2004 patients were randomized in arm A (only whole breast radiotherapy, WBRT) and arm B (WBRT + boost). The QA program involved 44 participant centers that performed the dummy run (DR). Compliance and uniformity of clinical target volume (CTV) delineations, and dose prescription and delivery according to the BONBIS trial radiotherapy guidelines were analyzed. Acute toxicities (during and up to 3 months after radiotherapy completion, NCI-CTCAE v3.0 classification) were evaluated in 1929 patients.

RESULTS

The differences in whole breast CTV (CTV1) and planning target volume (PTV1) were ≤10%, and the differences in boost CTV (CTV2) and PTV (PTV2) were ≥20% compared with the reference DR values; 95% of the prescribed dose encompassed 98.7% and 100% of the median CTV1 and CTV2. Grade ≥2 breast erythema (38.3% vs. 22.4% of grade 2 and 5.4% vs. 2.1% of grade 3, p < 0.001), grade ≥2 dermatitis (2.8% vs. 0.7%, p < 0.001), and grade 2 hyperpigmentation (6.9% vs. 3.6%, p = 0.005) were more frequent in arm B than arm A. No acute lung or cardiac toxicity was observed. Smoking history, large breast size, and large breast CTV were strong predictive factors of grade ≥2 acute skin toxicities.

CONCLUSIONS

The QA program showed deviations in breast and tumor bed delineation. The boost significantly increased acute skin toxicities.

Intraoperative marking of the tumour resection surface for improved radiation therapy planning in head and neck cancer: preclinical evaluation of a novel liquid fiducial marker

OBJECTIVE

To evaluate a novel liquid fiducial marker for intraoperative marking of the tumour resection surface in oral cancer patients to facilitate precise postoperative delineation of the interface between the tumour resection border and reconstructed tissue for intensity-modulated radiation therapy.

METHODS

A total of 200 markers were created by injecting the volumes of 10 µl, 20 µl, 30 µl, 40 µl and 50 µl of a liquid marker composed of sucrose acetoisobutyrate (SAIB) and iodinated sucrose acetoisobutyrate (x-SAIB) into the soft tissue of porcine mandible segments. Visibility of the resulting markers was quantified by threshold-based segmentation of the marker volume in CT- and CBCT imaging and by a comparison of signal intensities in MRI.

RESULTS

Even the lowest volume of SAIB-/x-SAIB investigated (10 µl) resulted in a higher visibility (CT_{Soft tissue}: 88.18 ± 13.23 µl; CT_Bone: 49.55 ± 7.62 µl; CBCT: 54.65 ± 12.58 µl) than observed with the incorporation of titanium ligature clips (CT_{Soft tissue}: 50.15 ± 7.50 mm³; CT_Bone: 23.90 ± 3.39 mm³; CBCT: 33.80 ± 9.20 mm³). Markers created by the injection of 10 µl and 20 µl could reliably be delineated from markers created by the injection of higher volumes.

CONCLUSION

SAIB/x-SAIB, which has recently become available as a Conformité Européenne (CE)-marked fiducial marker, provides an option for fast and reliable production of markers with excellent visibility in imaging modalities used in oral cancer radiation therapy (RT) planning routine.

A Three-Dimensional Bioabsorbable Tissue Marker for Volume Replacement and Radiation Planning: A Multicenter Study of Surgical and Patient-Reported Outcomes for 818 Patients with Breast Cancer

Background

Accurate identification of the tumor bed after breast-conserving surgery (BCS) ensures appropriate radiation to the tumor bed while minimizing normal tissue exposure. The BioZorb^® three-dimensional (3D) bioabsorbable tissue marker provides a reliable target for radiation therapy (RT) planning and follow-up evaluation while serving as a scaffold to maintain breast contour.

Methods

After informed consent, 818 patients (826 breasts) implanted with the BioZorb^® at 14 U.S. sites were enrolled in a national registry. All the patients were prospectively followed with the BioZorb^® implant after BCS. The data collected at 3, 6, 12, and 24 months included all demographics, treatment parameters, and provider/patient-assessed cosmesis.

Results

The median follow-up period was 18.2 months (range, 0.2–53.4 months). The 30-day breast infection rate was 0.5 % of the patients (n = 4), and re-excision was performed for 8.1 % of the patients (n = 66), whereas 2.6 % of the patients (n = 21) underwent mastectomy. Two patients (0.2 %) had local recurrence. The patient-reported cosmetic outcomes at 6, 12, and 24 months were rated as good-to-excellent by 92.4 %, 90.6 %, and 87.3 % of the patients, respectively and similarly by the surgeons. The radiation oncologists reported planning of target volume (PTV) reduction for 46.2 % of the patients receiving radiation boost, with PTV reduction most commonly estimated at 30 %.

Conclusions

This report describes the first large multicenter study of 818 patients implanted with the BioZorb^® tissue marker during BCS. Radiation oncologists found that the device yielded reduced PTVs and that both the patients and the surgeons reported good-to-excellent long-term cosmetic outcomes, with low adverse effects. The BioZorb^® 3D tissue marker is a safe adjunct to BCS and may add benefits for both surgeons and radiation oncologists.

Electronic supplementary material

The online version of this article (10.1245/s10434-020-09271-2) contains supplementary material, which is available to authorized users.

Contribution of Magnetic Resonance Imaging in Determining Lumpectomy Cavity in Breast Radiotherapy

BACKGROUND

Accurate localization of the lumpectomy cavity is important for breast cancer radiotherapy after breast-conserving surgery (BCS), but the LC localization based on CT is often difficult to delineate accurately. The study aimed to compare CT-defined LC planning to MRI-defined findings in the supine position for higher soft-tissue resolution of MRI.

METHODS

Fifty-nine breast cancer patients underwent radiotherapy CT planning in supine position followed by MR imaging on the same day. LC was contoured by the radiologist and radiation oncologist together by CT and MRI separately. T2 weighted MR images and tomography findings were combined and the LC volume, mean diameter and the longest axis length were measured after contouring. Subsequently, patients were divided into two groups according to seroma in LC and the above-mentioned parameters were compared.

RESULTS

We did not find any statistically significant difference in the LC volume, mean diameter and length at the longest axis between CT and MRI but based on the presence or absence of seroma, statistically significant differences were found in the LC volumes and the length at the longest axis of LC volumes.

CONCLUSION

We believe that the supine MRI in the same position with CT will be more effective for radiotherapy planning, particularly in patients without a seroma in the surgical cavity.

Comparison of postoperative CT- and preoperative MRI-based breast tumor bed contours in prone position for radiotherapy after breast-conserving surgery

Objectives

To compare the target volume of tumor bed defined by postoperative computed tomography (post-CT) in prone position registered with or without preoperative magnetic resonance imaging (pre-MRI).

Methods

A total of 22 patients were included with early-stage breast invasive ductal cancer, who have undergone breast-conservative surgery and received the pre-MRI and post-CT in prone position. The MRI sequences (T1W, T2W, T2W-SPAIR, DWI, dyn-eTHRIVE, sdyn-eTHRIVE) were delineated and manually registered to CT, respectively. The clinical target volumes (CTVs) and planning target volumes (PTVs) were contoured on CT and different MRI sequences, respectively. Differences were measured in terms of consistence index (CI), dice coefficient (DC), geographical miss index (GMI), and normal tissue index (NTI).

Results

The differences of delineation volumes among CT and MRIs were significant, both in the CTVs (p = 0.035) and PTVs (p < 0.001). The values of CI and DC for sdyn-eTHRIVE registration to CT were the largest among all MRI sequences, but GMI and NTI were the smallest. No obvious linear correlation (p > 0.05) between the CI derived from the registration of CT and sdyn-eTHRIVE of CTV with the breast volume, the cavity visualization score (CVS) of CT, time interval from surgery to CT simulation, the maximum diameter of the intraoperative mass, and the number of titanium clips, respectively.

Conclusions

The CTVs and PTVs in MRI sequences were all smaller than those in CT. The pre-MRI, especially the sdyn-eTHRIVE, could be used to optimize the post-CT-based target delineation of breast cancer.

Key Points

• Registered pre-MRI to post-CT in order to improve the accuracy of target volume delineation of breast cancer.

• The CTVs and PTVs in MRI sequences were all smaller than those in CT.

• The sdyn-eTHRIVE of pre-MRIs may be a better choice to improve the delineation of CT-based CTV and PTV.

Electronic supplementary material

The online version of this article (10.1007/s00330-020-07085-0) contains supplementary material, which is available to authorized users.

Oncoplastic Repair in Breast Conservation: Comprehensive Evaluation of Techniques and Oncologic Outcomes of 937 Patients

BACKGROUND

Breast-conserving surgery, especially with oncoplastic breast surgery (OBS), is becoming the standard of care in the surgical management of breast cancer. We investigated the applied technique of OBS and oncologic outcomes in a large series of patients.

PATIENTS AND METHODS

This study was conducted between January 2008 and June 2018 in two centers in Iran. Patients underwent OBS. Early and late postoperative complications, oncologic outcomes, and follow-up data were documented.

RESULTS

Nine hundred thirty-seven patients with a mean ± standard deviation age of 48.1 ± 11.3 underwent OBS. Most of the patients were diagnosed with early-stage disease, of which the most common pathology was invasive ductal carcinoma (83.3%). Lateral oncoplasty was the most commonly used OBS technique (324 cases, 34.6%). The most common complication was seroma formation. Reduction-type OBS technique had the highest rate of complications (13.1%). Thirty-four patients (5.4%) experienced local recurrence, with a median recurrence time of 26.4 months. Nine patients (1.3%) died from cancer recurrence.

CONCLUSION

OBS is a safe procedure with minor complications and good oncologic outcomes. These techniques can be applied to most patients who are candidates for breast-conserving surgery.

Comparing Breast Conservation Surgery Seromas Contoured by Radiation Therapists versus those Contoured by a Radiation Oncologist in Radiation Therapy Planning for Early-Stage Breast Cancer

INTRODUCTION

In the management of early-stage breast cancer using radiation therapy, computed tomography (CT) simulation is used to identify the breast conservation surgery (BCS) seroma as a proxy for the tumour bed. The delineation or contouring of the seroma is generally a task performed by a radiation oncologist (RO). With increasing patient numbers and other demands placed on ROs, the scope of practice for radiation therapists (RTs) is continually expanding, and the need for skills transfer from one profession to another has been investigated in recent years. This study aims to compare the BCS seroma volumes contoured by RTs with those contoured by ROs to add evidence in support of expanding the RTs' role in the treatment planning process in the management of early-stage breast cancer.

METHODS

A study was undertaken using the CT-simulation (CT-sim) data sets of patients with early-stage breast cancer treated in 2013. The CT-sim data sets had BCS seromas contoured by 1 of 5 ROs as part of routine clinical management. This study involved 4 RTs who each used the patient information to identify and contour breast seromas on 50 deidentified CT-sim data sets. Metrics used to compare RT versus RO contours included volume size, overlap between volumes, and geographical distance from the centre of volumes.

RESULTS

There were 50 CT-sim data sets with 1 RO contour and 4 RT contours analysed. The contour volumes of the 4 RTs and the ROs were assessed. Although there were 50 CT-sim data sets presented to each RT, analysis was carried out on 45, 43, 46, and 45 CT-sim data sets. There were no comparisons made where contours were not delineated. The contour volumes of the 4 RTs and the ROs were assessed with an interclass correlation coefficient, with a result of excellent reliability (0.975, 95% [0.963, 0.985]). The DICE similarity coefficient was used to compare the overlap of each RT contour with the RO contour; the results were favourable with mean (95% CI) DSCs 0.685, 0.640, 0.678, and 0.681, respectively. Comparing the RT and RO geographical centre of the seroma volumes, good to excellent reliability between the RTs and ROs was demonstrated (95% CI mean RO vs RT distances (mm): 3.75, 4.99, 7.71, and 3.39). There was no statistically significant difference between the distances (P = 0.65).

CONCLUSION

BCS seromas contoured by RTs compared well with those contoured by an RO. This research has provided further evidence to support RTs in assuming additional contouring responsibilities in radiation therapy planning for patients with early-stage breast cancer.

Daily localization of partial breast irradiation patients with three-dimensional ultrasound imaging

Purpose

Accurate localization of the lumpectomy cavity during accelerated partial breast radiation (APBR) is essential for daily setup to ensure the prescribed dose encompasses the target and avoids unnecessary irradiation to surrounding normal tissues. Three-dimensional ultrasound (3D-US) allows direct visualization of the lumpectomy cavity without additional radiation exposure. The purpose of this study was to evaluate the feasibility of 3D-US in daily target localization for APBR.Materials and methods: Forty-seven patients with stage I breast cancer who underwent breast conserving surgery were treated with a 2-week course of APBR. Patients with visible lumpectomy cavities on high quality 3D-US images were included in this analysis. Prior to each treatment, X-ray and 3D-US images were acquired and compared to images from simulation to confirm accurate position and determine shifts. Volume change of the lumpectomy cavity was determined daily with 3D-US.

Results

A total of 118 images of each modality from 12 eligible patients were analyzed. The average change in cavity volume was 7.8% (range, -24.1% to 14.4%) on 3D-US from simulation to the end-of-treatment. Based on 3D-US, significantly larger shifts were necessary compared to portal films in all three dimensions: anterior/posterior (p = 7E-11), left/right (p = 0.002), and superior/inferior (p = 0.004).

Conclusion

Given that the lumpectomy cavity is not directly visible via X-ray images, accurate positioning may not be fully achieved by X-ray images. Therefore, when the lumpectomy cavity is visible on US, 3D-US can be considered as an alternative to X-ray imaging during daily positioning for selected patients treated with APBR, thus avoiding additional exposure to ionizing radiation.

Displacement of Surgical Clips in Patients with Human Acellular Dermal Matrix in the Excision Cavity during Whole Breast Irradiation Following Breast-Conserving Surgery

PURPOSE

The purpose of this study was to investigate the displacement of surgical clips in the excision cavity during whole breast irradiation following breast-conserving surgery (BCS) with or without acellular dermal matrix (ADM) insertion, and to analyze clinicopathologic factors associated with the displacement of surgical clips.

MATERIALS AND METHODS

From 2016 to 2017, 100 consecutive breast cancer patients who underwent BCS with the placement of surgical clips (superior, inferior, medial, lateral, and deep sides) in the tumor bed were included in this study. All patients took first planning computed tomography (CT) scan (CT 1) before whole breast irradiation and second CT scan (CT 2) before boost irradiation. Between two sets of planning CT, the displacement of surgical clips was calculated from the ΔX (lateral-medial), ΔY (anterior-posterior), ΔZ (superior-inferior), and three-dimensional (3D) directions. Patients were divided into two groups according to the breast volume replacement with ADM: group A with ADM and group B without ADM.

RESULTS

The means and 1 standard deviations of 3D displacement for superior, inferior, medial, lateral and deep clips were 5.2±2.9, 5.2±3.2, 5.6±4.5, 5.6±4.3, and 4.9±4.9 mm in entire cohort (n=100); 5.6±2.6, 6.0±3.5, 6.7±5.8, 6.7±5.7, and 6.1±7.4 mm in group A (n=38); 4.9±3.1, 4.8±3.0, 5.0±3.5, 5.0±2.9, and 4.3±2.8 mm in group B (n=62), respectively. The 3D displacements of group A were longer than those of group B, but only significant difference was observed in lateral clip (p=0.047).

CONCLUSION

This study demonstrated displacement of surgical clips during whole breast irradiation in patients with ADM insertion. For patients who had breast volume replacement using ADM, adaptive boost planning should be considered.

Interobserver variability (between radiation oncologist and radiation therapist) in tumor bed contouring after breast-conserving surgery

PURPOSE

To examine interobserver variability between the radiation oncologist (RTO) and the radiation therapist (RTT) in delineating the tumor bed (TB) in early breast cancer (BC).

METHODS

We retrospectively analyzed patients who received a radiotherapy boost to the TB. In a first group, the clinical target volume (CTV) for the boost was the surgical bed, defined by using surgical clips. In a second group, the CTV was defined by identifying a seroma cavity or a metallic find on the scar. These contours were compared in terms of volume, number of slices, and Dice similarity coefficient (DSC).

RESULTS

Forty patients were assessed: 20 had surgical clips (group 1) while the other 20 had none (group 2). There was no difference in the number of slices contoured by the 2 operators for group 1, but a statistically significant difference emerged in the volumes: the RTT identified a TB that was a mean 45% smaller than the one identified by the RTO. Random differences were found between the 2 operators for group 2. The TBs delineated for this group were significantly larger (P<0.05) than those identified by the RTT for group 1. The mean Dice value between the RTO's and the RTT's TBs was 0.69±0.07 (range 0.53-0.81) for group 1 and 0.37±0.18 (range 0-0.58) for group 2 (P<0.05).

CONCLUSIONS

This study showed that the use of clips coincided with less interoperator variability. With appropriate training, the RTT may play an important part in the multidisciplinary radiotherapy team.

Tumour bed localisation after oncoplastic breast conservative surgery: a comparative contouring study

Purpose

To investigate the modalities of tumour bed (TB) localisation of target volume delineation [clinically computed tomography (CT), ultrasound (US) compared with surgical clips-guided] and the impact of their differences in delineated TB volumes.

Material and methods

In total, 27 patients who underwent oncoplastic breast conservative surgery with surgical clips insertion (at least three) were included. CT and US imaging for TB localisation were done 3–4 weeks post-operatively in the same treatment position. TB was delineated four times, guided by surgical clips, clinical data, CT (seroma) and US. A plan was done for each TB delineated. The four delineated volumes were compared regarding the volumetric differences, the geographical miss index (GMI) and the overlap index.

Results

Comparing the four modalities, median TB volume was for clinical (60.7), CT (60.8) and US (49.3) cm3, in comparison with 59.7 cm3 for clips, p=0.05. Median of GMI (represented the tissue at risk of recurrence and not had been treated) was for clinical (61.8), CT (45) and US (62.4)%, with significant difference of p=0.02. Median of normal tissue index (normal tissue has been included unnecessarily) was for clinical (59.5), CT (49.6) and US (62.3)%, p=0.17. Overlap index with clips-guided was for clinical (0.36), CT (0.42) and US (0.35) with significance of p=0.04. Median superior/inferior direction was 0.72, −0.03 and −0.2 cm for clinical, CT and US, respectively, with significant value of p=0.02, whereas the anterior–posterior was −0.07, −0.15 and −0.09 cm, p-value=0.45 and the medio–lateral was 0.4, −0.13 and 0.09 cm, p=0.60.

Conclusion

Significant differences in shifts and indices were detected between each of modalities compared with surgical clips. Thus, in the setting of oncoplastic breast surgery, surgical clips should be routinely used for TB localisation. In view of the larger volumes of breast tissue excised and the extensive remodelling that are inherent to oncoplastic procedures, the concept of TB boost irradiation should be re-challenged.

Improving oncoplastic breast tumor bed localization for radiotherapy planning using image registration algorithms

Knowledge about tumor bed localization and its shape analysis is a crucial factor for preventing irradiation of healthy tissues during supportive radiotherapy and as a result, cancer recurrence. The localization process is especially hard for tumors placed nearby soft tissues, which undergo complex, nonrigid deformations. Among them, breast cancer can be considered as the most representative example. A natural approach to improving tumor bed localization is the use of image registration algorithms. However, this involves two unusual aspects which are not common in typical medical image registration: the real deformation field is discontinuous, and there is no direct correspondence between the cancer and its bed in the source and the target 3D images respectively. The tumor no longer exists during radiotherapy planning. Therefore, a traditional evaluation approach based on known, smooth deformations and target registration error are not directly applicable. In this work, we propose alternative artificial deformations which model the tumor bed creation process. We perform a comprehensive evaluation of the most commonly used deformable registration algorithms: B-Splines free form deformations (B-Splines FFD), different variants of the Demons and TV-L¹ optical flow. The evaluation procedure includes quantitative assessment of the dedicated artificial deformations, target registration error calculation, 3D contour propagation and medical experts visual judgment. The results demonstrate that the currently, practically applied image registration (rigid registration and B-Splines FFD) are not able to correctly reconstruct discontinuous deformation fields. We show that the symmetric Demons provide the most accurate soft tissues alignment in terms of the ability to reconstruct the deformation field, target registration error and relative tumor volume change, while B-Splines FFD and TV-L¹ optical flow are not an appropriate choice for the breast tumor bed localization problem, even though the visual alignment seems to be better than for the Demons algorithm. However, no algorithm could recover the deformation field with sufficient accuracy in terms of vector length and rotation angle differences.

Impact of a Novel Bioabsorbable Implant on Radiation Treatment Planning for Breast Cancer

BACKGROUND

Techniques for accurately delineating the tumor bed after breast-conserving surgery (BCS) can be challenging. As a result, the accuracy, and efficiency of radiation treatment (RT) planning can be negatively impacted. Surgically placed clips or the post-surgical seroma are commonly used to determine target volume; however, these methods can lead to a high degree of uncertainty and variability. A novel 3-dimensional bioabsorbable marker was used during BCS and assessed for its impact on RT planning.

METHODS

One hundred and ten implants were sutured to the margins of the tumor bed excision site in 108 patients undergoing BCS. Routine CT imaging of the breast tissue was performed for RT planning, and the marker was assessed for visibility and utility in target delineation. RT regimens, target volumes and associated treatment costs were analyzed.

RESULTS

In all patients, the marker was easily visible and in 95.7 % of cases, it proved useful for RT planning. 36.8 % of patients received conventional whole breast irradiation plus boost, 56.6 % received hypo-fractionation plus boost, and 6.6 % received accelerated partial breast irradiation. A shift toward increased use of hypo-fractionated regimens was noted over the three year period of this study. There were no device-related complications or cancer recurrences in this group of patients.

CONCLUSIONS

This study demonstrated the use of a novel 3-dimensional marker as a safe and effective method for delineating the tumor bed with a significant utility for RT planning. With routine use of the device, an increased use of hypofractionation with a resultant 25 % cost savings was noted.

To clip or not to clip the breast tumor bed? A retrospective look at the geographic miss index and normal tissue index of 110 patients with breast cancer

OBJECTIVE

Planning of breast radiation for patients with breast conserving surgery often relies on clinical markers such as scars. Lately, surgical clips have been used to identify the tumor location. The purpose of this study was to evaluate the geographic miss index (GMI) and the normal tissue index (NTI) for the electron boost in breast cancer treatment plans with and without surgical clips.

MATERIAL AND METHODS

A retrospective descriptive study of 110 consecutive post-surgical patients who underwent breast-conserving treatment in early breast cancer, in which the clinical treatment field with the radiologic (clipped) field were compared and GMI/NTI for the electron boost were calculated respectively.

RESULTS

The average clinical field was 100 mm (range, 100-120 mm) and the clipped field was 90 mm (range, 80-100 mm). The average GMI was 11.3% (range, 0-44%), and the average NTI was 27.5% (range, 0-54%). The GMI and NTI were reduced through the use of intra-surgically placed clips.

CONCLUSION

The impact of local tumor control on the survival of patients with breast cancer is also influenced by the precision of radiotherapy. Additionally, patients demand an appealing cosmetic result. This makes "clinical" markers such as scars unreliable for radiotherapy planning. A simple way of identifying the tissue at risk is by intra-surgical clipping of the tumor bed. Our results show that the use of surgical clips can reduce the diameter of the radiotherapy field and increase the accuracy of radiotherapy planning. With the placement of surgical clips, more tissue at risk is included in the radiotherapy field. Less normal tissue receives radiotherapy with the use of surgical clips.

Displacement of Surgical Clips during Postoperative Radiotherapy in Breast Cancer Patients Who Received Breast-Conserving Surgery

PURPOSE

Surgical clips are used as a target for postoperative breast radiotherapy, and displacement of surgical clips would result in inaccurate delivery of radiation. We investigated the displacement range of surgical clips in the breast during postoperative radiotherapy following breast-conserving surgery.

METHODS

A total of 178 patients who received breast-conserving surgery and postoperative radiation of 59.4 Gy in 33 fractions to the involved breast for 6.5 weeks were included. Surgical clips were used to mark the lumpectomy cavity during breast-conserving surgery. Patients undertook planning computed tomography (CT) scan for whole breast irradiation. Five weeks after beginning radiation, when the irradiation dose was 45 Gy, planning CT scan was performed again for a boost radiotherapy plan in all patients. The surgical clips were defined in both CT images and compared in lateromedial (X), anteroposterior (Y), superoinferior (Z), and three-dimensional directions.

RESULTS

The 90th percentile of displacement of surgical clips was 5.31 mm (range, 0.0-22.2 mm) in the lateromedial direction, 7.1 mm (range, 0.0-14.2 mm) in the anteroposterior direction, and 6.0 mm (range, 0.0-10.0 mm) in the superoinferior direction. The 90th percentile of three-dimensional displacement distance was 9.8 mm (range, 0.0-28.2 mm). On the multivariate analysis, seroma ≥15 mL was the only independent factor associated with the displacement of surgical clips. In patients with seroma ≥15 mL, the 90th percentile of displacement of surgical clips was 15.1 mm in the lateromedial direction, 12.7 mm in the anteroposterior direction, 10.0 mm in the superoinferior direction, and 21.8 mm in the three-dimensional distance.

CONCLUSION

A target volume expansion of 10 mm from surgical clips may be sufficient to compensate for the displacement of clips during postoperative radiotherapy after breast-conserving surgery. For patients who had a seroma, a replanning CT scan for a boost radiation should be considered to ensure exact postoperative radiotherapy in breast cancer.

External beam radiation techniques for breast cancer in the new millennium: New challenging perspectives

Radiation therapy in breast cancer has evolved dramatically over the past century. It has traveled a long path touching different milestones and taking unprecedented turns. At the end, a fine tune of clinical understanding, skill, technological advancement and translation of radiobiological understanding to clinical outcome has taken place. What all these have given is better survival with quality survivorship. It is thus prudent to understand breast irradiation in a new perspective suitable for the current millennium.

Comparison of two radiation techniques for the breast boost in patients undergoing neoadjuvant treatment for breast cancer

OBJECTIVE

After breast conservative surgery (BCS) and whole-breast radiotherapy (WBRT), the use of boost irradiation is recommended especially in patients at high risk. However, the standard technique and the definition of the boost volume have not been well defined.

METHODS

We retrospectively compared an anticipated pre-operative photon boost on the tumour, administered with low-dose fractionated radiotherapy, and neoadjuvant chemotherapy with two different sequential boost techniques, administered after BCS and standard adjuvant WBRT: (1) a standard photon beam (2) and an electron beam technique on the tumour bed of the same patients. The plans were analyzed for the dosimetric coverage of the CT-delineated irradiated volume. The minimal dose received by 95% of the target volume (D95), the minimal dose received by 90% of the target volume (D90) and geographic misses were evaluated.

RESULTS

15 patients were evaluated. The sequential photon and electron boost techniques resulted in inferior target volume coverage compared with the anticipated boost technique, with a median D95 of 96.3% (range 94.7-99.6%) and 0.8% (range 0-30%) and a median D90 of 99.1% (range 90.2-100%) and 54.7% (range 0-84.8%), respectively. We observed a geographic miss in 26.6% of sequential electron plans. The results of the anticipated boost technique were better: 99.4% (range 96.5-100%) and 97.1% (range 86.2-99%) for median D90 and median D95, respectively, and no geographic miss was observed. We observed a dose reduction to the heart, with left-sided breast irradiation, using the anticipated pre-operative boost technique, when analyzed for all dose-volume parameters. When compared with the sequential electron plans, the pre-operative photon technique showed a higher median ipsilateral lung Dmax.

CONCLUSION

Our data show that an anticipated pre-operative photon boost results in a better coverage with respect to the standard sequential boost while also saving the organs at risk and consequently fewer side effects.

ADVANCES IN KNOWLEDGE

This is the first dosimetric study that evaluated the association between an anticipated boost and neoadjuvant chemotherapy treatment.

A clip-based protocol for breast boost radiotherapy provides clear target visualisation and demonstrates significant volume reduction over time

Introduction

The clinical target volume (CTV) for early stage breast cancer is difficult to clearly identify on planning computed tomography (CT) scans. Surgical clips inserted around the tumour bed should help to identify the CTV, particularly if the seroma has been reabsorbed, and enable tracking of CTV changes over time.

Methods

A surgical clip-based CTV delineation protocol was introduced. CTV visibility and its post-operative shrinkage pattern were assessed. The subjects were 27 early stage breast cancer patients receiving post-operative radiotherapy alone and 15 receiving post-operative chemotherapy followed by radiotherapy. The radiotherapy alone (RT/alone) group received a CT scan at median 25 days post-operatively (CT1rt) and another at 40 Gy, median 68 days (CT2rt). The chemotherapy/RT group (chemo/RT) received a CT scan at median 18 days post-operatively (CT1ch), a planning CT scan at median 126 days (CT2ch), and another at 40 Gy (CT3ch).

Results

There was no significant difference (P = 0.08) between the initial mean CTV for each cohort. The RT/alone cohort showed significant CTV volume reduction of 38.4% (P = 0.01) at 40 Gy. The Chemo/RT cohort had significantly reduced volumes between CT1ch: median 54 cm³ (4–118) and CT2ch: median 16 cm³, (2–99), (P = 0.01), but no significant volume reduction thereafter.

Conclusion

Surgical clips enable localisation of the post-surgical seroma for radiotherapy targeting. Most seroma shrinkage occurs early, enabling CT treatment planning to take place at 7 weeks, which is within the 9 weeks recommended to limit disease recurrence.

The effect of image guidance on dose distributions in breast boost radiotherapy

AIMS

To determine the effect of image-guided radiotherapy on the dose distributions in breast boost treatments.

MATERIALS AND METHODS

Computed tomography images from a cohort of 60 patients treated within the IMPORT HIGH trial (CRUK/06/003) were used to create sequential and concomitant boost treatment plans (30 cases each). Two treatment plans were created for each case using tumour bed planning target volume (PTV) margins of 5 mm (achieved with image-guided radiotherapy) and 8 mm (required for bony anatomy verification). Dose data were collected for breast, lung and heart; differences with margin size were tested for statistical significance.

RESULTS

A median decrease of 29 cm(3) (range 11-193 cm(3)) of breast tissue receiving 95% of the prescribed dose was observed where image-guided radiotherapy margins were used. Decreases in doses to lungs, contralateral breast and heart were modest, but statistically significant (P < 0.01). Plan quality was compromised with the 8 mm PTV margin in one in eight sequential boost plans and one third of concomitant boost plans. Tumour bed PTV coverage was <95% (>91%) of the prescribed dose in 12 cases; in addition, the required partial breast median dose was exceeded in nine concomitant boost cases by 0.5-3.7 Gy.

CONCLUSIONS

The use of image guidance and, hence, a reduced tumour bed PTV margin, in breast boost radiotherapy resulted in a modest reduction in radiation dose to breast, lung and heart tissues. Reduced margins enabled by image guidance were necessary to discriminate between dose levels to multiple PTVs in the concomitant breast boost plans investigated.

Plastic surgery for breast conservation therapy: how to define the volume of the tumor bed for the boost?

PURPOSE

To describe the procedure of definition of the boost volume using pre- and post-operative computed tomography (CT) and surgical clips in the tumor bed after oncoplastic surgical procedure.

PATIENTS AND METHODS

Thirty-one consecutive breast cancer patients who underwent simple lumpectomy or oncoplastic surgery were studied. All of them underwent pre- and post-operative CT scan in treatment position to evaluate the planning target volume (PTV) boost volume and define the primary tumor (gross tumor volume (GTV)) and tumor bed zones (CTV), with an overall margin of 5 mm in lateral and 10 mm in craniocaudal directions, corresponding to localization and setup uncertainties.

RESULTS

Thirteem patients underwent simple lumpectomy and 18 oncoplastic surgery. The volumetric analysis showed that the intersection between GTV and CTV clips was significantly higher in patients with three and more clips (28.4% vs 3.14%; p < 0.001). In the case of patients with oncoplastic surgery, more than three clips were needed to define the tumor bed volume with accuracy. The number of clips was directly related to the exact definition of the boost volume.

CONCLUSIONS

The use of more than three clips allows better definition of the PTV boost volume after oncoplastic surgical procedure.

Tumour bed clip localisation for targeted breast radiotherapy: compliance is proportional to trial-related research activity: tumour bed clip localisation in breast radiotherapy

BACKGROUND

In breast cancer, with the increasing use of intensity-modulated radiotherapy (IMRT), the need for accurate tumour bed localisation is paramount. We determined current practice of clip usage in patients referred to a regional centre for radiotherapy following breast conserving surgery. We also investigated whether participation of surgical units in IMRT trials, where tumour bed clip use is emphasised, was associated with clip insertion.

METHODS

A retrospective cohort study of consecutive CT planning images (n = 205), of breast cancer patients treated with radiotherapy following breast conserving surgery. Presence and number of clips; referring hospital and referring surgeon of the patient was recorded. This was correlated to previous participation of referring hospital to IMRT trials.

RESULTS

Of 196 eligible patients, 126 (64%) had clips sited, of which 15 (12%) had two or fewer clips. Five referring hospitals were high recruiters (≥14 patients), and five hospitals were low/non-recruiters (≤1 patient) to IMRT trials. Of patients from low/non-recruiting centres, 29 of 43 (67%) had clips omitted, compared to 41 of 153 (27%) from high-recruiting centres (p < 0.001). Median number of clips used in centres recruiting high numbers of patients was four, compared to zero in low recruiting centres. Ten of 31 referring surgeons routinely omitted clips.

CONCLUSION

Despite inclusion in national guidelines, clip insertion has not become routine in the UK in patients undergoing breast conserving surgery. However, hospitals involved in breast radiotherapy randomised controlled trials are more compliant with clip usage recommendations. Auditing of clip insertion should be considered as a quality control marker in breast surgery.

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.

Breast radiotherapy: less is more?

A 3 week schedule of whole breast radiotherapy is firmly established in the UK and is becoming more accepted internationally, especially as accelerated partial breast radiotherapy regimens become more common. It seems that a 3 week schedule is unlikely to be the lower limit of whole breast hypofractionation and the partial breast may even be adequately treated with just a single treatment. It is, however, essential that these hypotheses are rigorously tested within well-designed trials to ensure the highest quality of radiotherapy. This overview will address the rationale for hypofractionation in breast cancer, discuss past trials and outline the design of current studies.

Adjuvant radiotherapy in the management of axillary node negative invasive breast cancer: a qualitative systematic review

PURPOSE

To actualize and to detail guidelines used in technical radiotherapy and indications for innovative radiation technologies in early axillary node negative breast cancer (BC).

METHODS

Dosimetric and treatment planning studies, phase II and III trials, systematic reviews and retrospective studies were all searched (Medline(®) database). Their quality and clinical relevance were also checked against validated checklists. A level of evidence was associated for each result.

RESULTS

A total of 75 references were included. Adjuvant BC radiotherapy (50Gy/25 fractions/5 weeks followed by a tumor boost of 16Gy/8 fractions) is still the standard of care. Overall treatment time could be shortened for patients who present with low local relapse risk BC by using either hypofractionated whole breast irradiation; or accelerated partial breast irradiation. BC IMRT is not used in current practice.

CONCLUSION

Our group aimed to provide guidelines for technical and clinical applications of innovative BC radiation technologies.

Volumetric changes in the lumpectomy cavity during whole breast irradiation after breast conserving surgery

Purpose

This study was performed to evaluate the change in the lumpectomy cavity volumes before and after whole breast radiation therapy (WBRT) and to identify factors associated with the change of volume.

Materials and Methods

From September 2009 to April 2010, the computed tomography (CT) simulation data from 70 patients obtained before and after WBRT was evaluated. The lumpectomy cavity volumes were contoured based on surgical clips, seroma, and postoperative changes. Significant differences in the data from pre-WBRT CT and post-WBRT CT were assessed. Multiple variables were examined for correlation with volume reduction in the lumpectomy cavity.

Results

The mean and median volume reduction in the lumpectomy cavity after WBRT were 17.6 cm³ and 16.1 cm³, respectively with the statistical significance (p < 0.001). The volume reduction in the lumpectomy cavity was inversely correlated with time from surgery to radiation therapy (R = 0.390). The presence of seroma was significantly associated with a volumetric change in the lumpectomy cavity after WBRT (p = 0.011).

Conclusion

The volume of lumpectomy cavity reduced significantly after WBRT. As the time from surgery to the start of WBRT increased, the volume reduction in the lumpectomy cavity during WBRT decreased. A strong correlation was observed between the presence of seroma and the reduced volume. To ensure appropriate coverage and to limit normal tissue exposure during boost irradiation in patients who has seroma at the time of starting WBRT, repeating CT simulation at boost planning is suggested.

Evaluation of implanted gold seeds for breast radiotherapy planning and on treatment verification: a feasibility study on behalf of the IMPORT trialists

BACKGROUND AND PURPOSE

We describe a feasibility study testing the use of gold seeds for the identification of post-operative tumour bed after breast conservation surgery (BCS).

MATERIALS AND METHODS

Fifty-three patients undergoing BCS for invasive cancer were recruited. Successful use was defined as all six seeds correctly positioned around the tumour bed during BCS, unique identification of all implanted seeds on CT planning scan and ≥ 3 seeds uniquely identified at verification to give couch displacement co-ordinates in 10/15 fractions. Planning target volume (PTV) margin size for four correction strategies were calculated from these data. Variability in tumour bed contouring was investigated with five radiation oncologists outlining five CT datasets.

RESULTS

Success in inserting gold seeds, identifying them at CT planning and using them for on-treatment verification was recorded in 45/51 (88%), 37/38 (97%) and 42/43 (98%) of patients, respectively. The clinicians unfamiliar with CT breast planning consistently contoured larger volumes than those already trained. Margin size ranged from 10.1 to 1.4mm depending on correction strategy.

CONCLUSION

It is feasible to implant tumour bed gold seeds during BCS. Whilst taking longer to insert than surgical clips, they have the advantage of visibility for outlining and verification regardless of the ionising radiation beam quality. Appropriate correction strategies enable margins of the order of 5mm as required by the IMPORT trials however, tackling clinician variability in contouring is important.

Impact of the radiation boost on outcomes after breast-conserving surgery and radiation

PURPOSE

We examined the impact of radiation tumor bed boost parameters in early-stage breast cancer on local control and cosmetic outcomes.

METHODS AND MATERIALS

A total of 3,186 women underwent postlumpectomy whole-breast radiation with a tumor bed boost for Tis to T2 breast cancer from 1970 to 2008. Boost parameters analyzed included size, energy, dose, and technique. Endpoints were local control, cosmesis, and fibrosis. The Kaplan-Meier method was used to estimate actuarial incidence, and a Cox proportional hazard model was used to determine independent predictors of outcomes on multivariate analysis (MVA). The median follow-up was 78 months (range, 1-305 months).

RESULTS

The crude cosmetic results were excellent in 54%, good in 41%, and fair/poor in 5% of patients. The 10-year estimate of an excellent cosmesis was 66%. On MVA, independent predictors for excellent cosmesis were use of electron boost, lower electron energy, adjuvant systemic therapy, and whole-breast IMRT. Fibrosis was reported in 8.4% of patients. The actuarial incidence of fibrosis was 11% at 5 years and 17% at 10 years. On MVA, independent predictors of fibrosis were larger cup size and higher boost energy. The 10-year actuarial local failure was 6.3%. There was no significant difference in local control by boost method, cut-out size, dose, or energy.

CONCLUSIONS

Likelihood of excellent cosmesis or fibrosis are associated with boost technique, electron energy, and cup size. However, because of high local control and rare incidence of fair/poor cosmesis with a boost, the anatomy of the patient and tumor cavity should ultimately determine the necessary boost parameters.