Hypofractionated whole breast IMRT with HDR brachytherapy boost in early-stage breast cancer: Long-term results from a single-center

INTRODUCTION/OBJECTIVES

The addition of a boost to the lumpectomy bed after whole-breast (WB) radiotherapy plays a key role in the treatment of patients with breast cancer (BC). The clinical benefits of a boost with high-dose-rate brachytherapy (HDR-BT) after conventional fractionation is supported by a large body of evidence. However, few studies have described its outcomes after a hypofractionated scheme.

MATERIALS AND METHODS

We included all patients treated with adjuvant WB-IMRT in 15 sessions followed by a single-session HDR-BT boost with local anesthesia on an outpatient basis.

RESULTS

Between 2009 and 2017, 638 patients with early-stage BC were treated according to the aforementioned protocol after breast-conserving surgery. Median follow-up was 6 years (4-11). Despite the low incidence of side effects and their slightness, we did identify an impact of breast volume on the risk of acute radiodermatitis, fibrosis, pain and edema. However, we did not identify any relationship between the volume in cubic centimeters of the BT-implant with acute or long-term side effects. 2.2% patients had an actual local relapse, 2.4% a 2nd primary in the same breast and 2.39% were diagnosed with contralateral BC. Event-free survival at 11 years was 85.5% with an overall survival of 95.7%.

CONCLUSION

Adjuvant hypofractionated whole-breast IMRT followed by a single dose HDR-BT boost has a low incidence of acute and chronic toxicity and excellent oncological outcomes. However, it may be worthwhile to intensify self-care protocols and surveillance in women with large breasts who may be at increased risk of side effects.

Use of immobilisation bra for daily setup of patients with pendulous breasts undergoing radiotherapy

PURPOSE

A feasibility study to evaluate the Chabner XRT® Radiation Bra (CIVCO Radiotherapy & Qfix, Coralville, IA, USA) as a customised immobilisation device for patients with pendulous breasts undergoing radiotherapy was conducted.

METHODS

A total of 34 patients with large pendulous breasts were fitted with the Chabner XRT® Radiation Bra during RT. A mixed-method questionnaire was administered to both radiation therapists (RTTs) and patients. RTTs evaluated the effectiveness of the bra in setup. Patients appraised its comfort level and ease of wearing. Setup reproducibility was evaluated based on a departmental imaging protocol. Acute skin side effects were documented with photos and assessed using the Radiation Therapy Oncology Group (RTOG) classification.

RESULTS

Of the patients, 27 (79.4%) completed the questionnaire. 23 patients felt comfortable wearing the bra while 20 felt less exposed during treatment. Reproducibility was acceptable, with a median (range) setup error (isocentre) of 0.0 cm (-0.6 to 0.7 cm; left/right), -0.1 cm (-0.5 to 1.2 cm; posterior) and 0.2 cm (-0.5 to 0.9 cm; inferior) achieved based on matched field borders on skin. However, repeated setups and imaging were required for 3 patients due to large breast size (cups D-G; size 4-5). Minimal skin toxicity (grade 0-1) was observed. No grade ≥ 2 was reported. 10 RTTs completed the survey. Male RTTs (n = 4) were not confident in assisting patients with bra fitting. 8 RTTs agreed that although it was difficult to reproduce the breast tissue for treatment, it helped patients to maintain the treatment position.

CONCLUSION

Our study demonstrated the feasibility of using a customised bra which provided optimal setup reproducibility while maintaining minimal skin toxicity and patient comfort, especially the value-added modesty felt among Asian women during their breast cancer radiotherapy.

Four irradiation and three positioning techniques for whole-breast radiotherapy: Is sophisticated always better?

PURPOSE

We report on a dosimetrical study of three patient positions (supine, prone dive, and prone crawl) and four irradiation techniques for whole-breast irradiation (WBI): wedged-tangential fields (W-TF), tangential-field intensity-modulated radiotherapy (TF-IMRT), multi-beam IMRT (MB-IMRT), and intensity-modulated arc therapy (IMAT). This is the first study to evaluate prone crawl positioning in WBI and the first study to quantify dosimetrical and anatomical differences with prone dive positioning.

METHODS

We analyzed five datasets with left- and right-sided patients (n = 51). One dataset also included deep-inspiration breath hold (DIBH) data. A total of 252 new treatment plans were composed. Dose-volume parameters and indices of conformity were calculated for the planning target volume (PTV) and organs-at-risk (OARs). Furthermore, anatomical differences among patient positions were quantified to explain dosimetrical differences.

RESULTS

Target coverage was inferior for W-TF and supine position. W-TF proved overall inferior, and IMAT proved foremost effective in supine position. TF-IMRT proved competitive to the more demanding MB-IMRT and IMAT in prone dive, but not in prone crawl position. The lung-sparing effect was overall confirmed for both prone dive and prone crawl positioning and was largest for prone crawl. For the heart, no differences were found between prone dive and supine positioning, whereas prone crawl showed cardiac advantages, although minor compared to the established heart-sparing effect of DIBH. Dose differences for contralateral breast were minor among the patient positions. In prone crawl position, the ipsilateral breast sags deeper and the PTV is further away from the OARs than in prone dive position.

CONCLUSIONS

The prone dive and prone crawl position are valid alternatives to the supine position in WBI, with largest advantages for lung structures. For the heart, differences are small, which establishes the role of DIBH in different patient positions. These results may be of particular interest to radiotherapy centers with limited technical resources.

Skin dose in radiation treatment of the left breast: Analysis in the context of prone versus supine treatment technique

PURPOSE

To determine how the skin dose varies in patients receiving radiation treatment for breast cancer in the prone and supine positions.

METHODS

Fifty patients were scanned in the prone and supine positions. A radiation treatment plan was created for the left breast using a 6-MV beam for a prescribed dose of 42.66 Gy in 16 fractions. The dose was calculated using 1- and 2.5-mm calculation grid sizes and the surface dose was compared in both techniques.

RESULTS

The median gantry angles relative to the skin surface at the central axis were 8 and 52 degrees for treatment in the prone and supine positions, respectively. The mean dose difference between the prone and supine techniques was statistically significant from 3- to 5-mm depth for both grid sizes. For the 1-mm calculation grid size, the doses at 3-, 4-, and 5-mm depths in the prone and supine techniques were 87.80% and 89.10% (P < 0.003), 91.92% and 94.50% (P < 0.00), and 95.30% and 98.20% (P < 0.00), respectively; for the 2.5-mm grid size, the respective doses were 87.10% and 88.59% (P < 0.00), 91.60% and 94.63% (P < 0.00), and 95.10% and 97.80% (P < 0.00), respectively.

CONCLUSIONS

This study demonstrates that the prone technique facilitates a relatively lower skin dose than the supine technique. This observation is probably due to the beam angle. The beam is more perpendicular to the skin surface in the prone technique, whereas it is more tangential in the supine technique, which may deliver a higher skin dose. Thus, the dose to the skin should be evaluated in the prone technique, and if desired, the skin dose could be carefully augmented via a bolus or beam spoiler.

Prone Positioning With Deep Inspiration Breath Hold for Left Breast Radiotherapy

BACKGROUND

With advances in treatment, outcomes for early-stage breast cancer are improving. We investigated the combination of prone position and deep inspiration breath hold to decrease cardiac doses for left-sided breast radiotherapy.

MATERIAL AND METHODS

Fifteen patients with left-sided breast cancer were enrolled on a single-institution prospective study. Each patient underwent 2 prone positioned computed tomography simulation scans utilizing free breathing and breath-hold. Separate treatment plans for each computed tomography simulation scan were created using tangential fields, and heart and left lung doses were compared between free breathing and breath-hold plans. The technique with the lower mean dose for the heart was used for treatment. All patients were treated with a hypofractionated regimen of 40 to 42 Gy in 15 to 16 fractions, followed by a lumpectomy cavity boost of 10 Gy in 5 fractions when indicated. Wilcoxon paired signed rank tests and paired t tests were performed for statistical analysis of dosimetric endpoints.

RESULTS

The median age of our patients was 58 years (range, 40-72 years). One patient was not able to tolerate prone positioning at simulation, leaving 14 patients with evaluable paired scans. The average mean heart dose with free breathing and with breath-hold was 0.93 Gy and 0.72 Gy, respectively (P = .0063). The average max heart dose with free breathing and with breath-hold was 15.70 Gy and 7.19 Gy, respectively (P = .001). The average mean left lung dose with free breathing and with breath-hold was 0.65 Gy and 0.88 Gy, respectively (P = .011).

CONCLUSIONS

Our results indicate that breath-hold using the real-time position management system may provide additional cardiac dose reduction in patients receiving prone left-breast radiotherapy treated with tangential fields.

A service evaluation of the immobilisation techniques adopted for breast cancer patients with large and/or pendulous breasts, receiving external beam radiotherapy

Introduction:

Breast cancer patients referred for external beam radiotherapy and who have large and/or pendulous breasts can present positioning and immobilisation challenges. Deep infra-mammary and/or lateral wrap skin folds can occur that can lead to unwanted radiation-induced skin toxicity. The purpose of the study was to evaluate the immobilisation techniques adopted for this subgroup of patients in order to inform best practice.

Method:

A survey aimed to identify the current clinical practice in radiotherapy centres throughout the United Kingdom and Ireland was undertaken. The email survey was distributed with support of the Radiotherapy Services Managers group.

Results:

Twenty-six of the 74 radiotherapy centres responded to the survey. Responses demonstrated that supine positioning with or without additional immobilisation was preferable. Of the eight different immobilisation techniques identified, patients positioned supine on a breast board wearing a bra was the most common. Only two of the centres reported using a prone technique.

Conclusions:

Immobilisation and reproducibility are key for successful external beam radiotherapy particularly when advanced treatment techniques are being employed. No single technique gained widespread acceptance as the optimum for the effective immobilisation of patients with large and/or pendulous breasts. Further evaluative research in the form of a multi-centre trial is warranted in order to clearly establish the most effective immobilisation methods/devices for this ever expanding, subgroup of cancer patients.

Evaluation of sparing organs at risk (OARs) in left-breast irradiation in the supine and prone positions and with deep inspiration breath-hold

Purpose

To compare doses to organs at risk (OARs) for left‐sided whole‐breast radiation therapy with comparable planning target volume (PTV) coverage using three techniques: free breathing in a supine position (SFB), deep inspirational breath‐hold in a supine position (SDIBH), and free breathing in prone position (PFB).

Materials and methods

Thirty‐three patients with left‐sided early‐stage breast cancer underwent CT simulation following SFB, SDIBH, and PFB protocols for whole‐breast radiation therapy. One radiation oncologist contoured the breast PTV, heart, left ventricle (LV), and left anterior descending artery (LAD). Treatment plans were optimized using field‐in‐field technique with the AAA algorithm. Each plan was optimized to provide identical coverage to the PTV such that a reasonable comparison for OAR dosimetry could be evaluated. All plans were prescribed 42.56 Gy in 16 fractions to the left‐breast PTV.

Results

The mean dose in SFB for the heart, LV, and LAD was 1.92, 3.19, and 21.73 Gy, respectively, which were significantly higher than the mean dose in SDIBH for the heart (1.08 Gy, P ≤ 0.0001), LV (1.50 Gy, P ≤ 0.0001), and LAD (6.3 Gy, P ≤ 0.0001) and in PFB for the heart (0.98 Gy, P ≤ 0.0001), LV (1.34 Gy, P ≤ 0.0001), and LAD (6.57 Gy, P ≤ 0.0001). Similar findings were noted for the cardiac components in SFB for V2.5, V5, V10, V20, and V30 compared with values in SDIBH and PFB. The mean dose for the left lung in PFB was 0.61 Gy that was significantly lower than in SFB (5.63 Gy, P ≤ 0.0001) and SDIBH (5.54 Gy, P ≤ 0.0001). Mean dose and dosimetric values for each OAR increased in SFB and SDIBH for patients with a large breast volume compared with values for patients with a small breast volume.

Conclusions

SFB results in higher heart, LAD, and LV doses than the other techniques. Both PFB and SDIBH are more advantageous for these OARs irrespective of breast volume. PFB results in significantly lower lung doses than SFB and SDIBH. PFB always provided better results than SFB for the heart, LV, LAD, and lung. This conclusion contrasts with some published studies concluding that the prone position has no benefit for heart sparing.

A dosimetry study precisely outlining the heart substructure of left breast cancer patients using intensity-modulated radiation therapy

The purpose of this study was to evaluate the feasibility of delineating the substructure of the heart by using 64‐slice spiral CT coronary angiography (CTA) in breast cancer patients who underwent left breast‐conserving surgery, and to compare the dosimetric differences between the targets and organs at risk in the prone and supine positions in intensity‐modulated radiation therapy (IMRT) planning. From January to December 2011, ten patients who underwent left breast‐conserving surgery were enrolled in this study. CTA was performed in both the supine and prone positions during the simulation, and conventional scanning without CTA was performed at the same time. Image registration was performed for paired image series using a commercially available planning system. In a conventional image series, the clinical target volume (CTV) of the whole breast, planning target volume (PTV), bilateral lungs (L‐Lung, R‐Lung), spinal cord, contralateral breast (R‐Breast), and heart were delineated. In the CTA image series, the left ventricular (LV) and left anterior descending coronary arteries (LAD) and the planning risk volume (LAD‐PRV) of the LAD (LAD with a 1 cm margin) were outlined. For each patient, two separate IMRT plans were developed for the supine and prone positions. A total of 20 plans were generated. The following indicators were compared: Dmean and D95 for the PTV; Dmean, V5, and V20 for the left lung; Dmean, V10, V20, V25, V30, and V40 for the heart and its substructures (LAD‐PRV, LV); Dmean and V5 for the right lung; and Dmax and Dmean for the right breast. Using CTA to delineate the substructures of the heart is simple and straightforward. Plans for both the prone and supine positions reached the prescribed dose for the PTV without significant differences. Dose distributions were acceptable for both the prone and supine positions. However, the LAD‐PRV, LV, heart, and L‐Lung received smaller doses in the prone position plans than in the supine position plans. The Dmean values reduced by 445.83cGy(p=0.043),575.00cGy(p=0.003),402.00cGy(p=0.039), and 553.33cGy(p=0.004) in the LAD‐PRV, LV, heart, and L‐Lung. In addition, the V25 lessened 12.54%(p=0.042) and 8.70%(p=0.019) in the LV and heart, while the V20 was decreased 8.57%(p=0.042),15.21%(p=0.026),12.59%(p=0.011), and 10.62%(p=0.006) in the LAD‐PRV, LV, heart, and L‐Lung, respectively. Similarly, the V10 and V30 were reduced by 28.31% (p=0.029) and 5.54%(p=0.034) in the heart, while the V5 was cut back 27.86%(p=0.031) in the L‐Lung. For most Asian women with average‐sized breasts after breast conserving treatment (BCT), prone positioning during IMRT radiation will reduce the dose to the ipsilateral lung, heart, and substructures of the heart, which may reduce the incidence of cardiovascular events after radiotherapy more than radiation therapy performed in a supine position. Using CTA to delineate the substructures of the heart is easy and intuitive. It is cost‐effective and highly recommended for breast cancer IMRT. However, the dose‐volume limits of the heart substructures remain to be determined.

PACS number: 87.55.dk