Elsevier

Practical Radiation Oncology

Volume 5, Issue 6, November–December 2015, Pages 358-365
Practical Radiation Oncology

Original Report
Prospective assessment of deep inspiration breath-hold using 3-dimensional surface tracking for irradiation of left-sided breast cancer

https://doi.org/10.1016/j.prro.2015.06.002Get rights and content

Abstract

Purpose

Deep inspiration breath hold (DIBH) is used to decrease cardiac irradiation during radiation therapy (RT) for breast cancer. The patients most likely to benefit and the impact on treatment time remain largely unknown. We sought to identify predictors for the use of DIBH and to quantify differences in dosimetry and treatment time using a prospective registry.

Methods and materials

A total of 150 patients with left breast cancer were enrolled. All patients were simulated with both free breathing (FB) and DIBH. RT was delivered by either modality. Alternate scans were planned with use of deformable registration to include identical RT volumes. DIBH patients were monitored by a real-time surface tracking system, AlignRT (Vision RT, Ltd, London, United Kingdom). Baseline characteristics and treatment times were compared by Fisher exact test and Wilcoxon rank sum test. Dosimetric endpoints were analyzed by Wilcoxon signed rank test, and linear regression identified predictors for change in mean heart dose (∆MHD).

Results

We treated 38 patients with FB and 110 with DIBH. FB patients were older, more likely to have heart and lung disease, and less likely to receive chemotherapy or immediate reconstruction (all P < .05). Treatment times were not significantly different, but DIBH patients had greater variability in times (P = .0002). Of 146 evaluable patients, DIBH resulted in > 20 cGy improvement in MHD in 107 patients but a > 20 cGy increase in MHD in 14. Both MHD and lung V20 were significantly lower in DIBH than in paired FB plans. On multivariate analysis, younger age (4.18 cGy per year; P < .0001), higher body mass index (6.06 cGy/kg/m2; P = .0018), and greater change in lung volumes (130 cGy/L; P = .003) were associated with greater ∆MHD.

Conclusions

DIBH improves cardiac dosimetry without significantly impacting treatment time in most patients. Greater inspiratory lung volumes augment this benefit. Because the improvement with DIBH was not uniform, patients should be scanned with both FB and DIBH.

Introduction

Adjuvant radiation therapy (RT) significantly improves both local control and overall survival in a majority of breast cancer (BC) patients after breast conservation therapy or mastectomy[1], [2], [3]; however, breast and chest wall (BCW) irradiation is also associated with higher non–BC-related mortality, likely from late cardiopulmonary toxicity.[4], [5], [6] Mortality from coronary heart disease (CHD) may explain the limited benefit from RT seen in earlier studies,[7], [8], [9] such that the true survival benefit from RT may be even greater when CHD is minimized.

One recent study demonstrated a linear relationship between mean heart dose (MHD) and major coronary events. Notably, there was no lower threshold for this effect.10 These data have renewed attention to techniques for limiting unintended cardiac irradiation. Deep inspiration breath hold (DIBH) is one such technique that aims to displace the heart from the chest wall during inspiration, thereby reducing the dose and volume of irradiated heart.[11], [12]

DIBH may be achieved with either active breathing control devices (ABC-DIBH) or voluntary patient coaching (voluntary DIBH). Despite robust data to support its use,[13], [14], [15], [16] difficulties with patient comfort and cost of equipment, including daily disposable mouthpieces, have limited widespread uptake of ABC-DIBH.17 Voluntary DIBH is an alternative noninvasive option, but it may be limited by precision and reproducibility. Tools for real-time motion assessment, including surface-tracking systems (AlignRT; Vision RT, Ltd, London, United Kingdom) and patient-centered techniques like active coaching and real-time patient feedback devices, have been implemented to ensure consistent inspiration during treatment.18

The efficacy and feasibility of voluntary DIBH, however, depend on a variety of patient- and tumor-specific factors, including individual anatomy, patient compliance, tumor location, and duration of treatment. We sought to understand the feasibility, dosimetric efficacy, and practical implications (treatment time and variability) of DIBH in a prospectively enrolled registry of patients scanned with free-breathing (FB) or DIBH but ultimately treated with either technique based on physician assessment. This study represents one of the largest cohorts of patients treated with DIBH published to date and one of the few to describe practical outcomes of DIBH during treatment.

Section snippets

Patient selection

Patients with left-sided BC undergoing RT were enrolled in a prospective registry at the Dana-Farber/Brigham and Women’s Cancer Center (DF/BWCC), including patients receiving any type of breast surgery, systemic therapy, or RT fields. All patients were deemed candidates for DIBH before radiation planning based on tumor location, general health status, and perceived ability to comply with DIBH. Patients provided consent for participation in this institutional review board–approved registry

Patient characteristics

A total of 150 patients were enrolled from 2011 to 2014; 2 withdrew consent, and 2 had incomplete dosimetry because of missing scans. Thirty-eight patients were treated with FB and 110 with DIBH. FB patients were older (P = .002), more likely to have pre-existing heart disease (P = .02) and lung disease (P = .05), and less likely to have received chemotherapy (P = .01) or immediate breast reconstruction (P = .01) relative to DIBH patients (Table 1). There were no other significant differences

Discussion

This study showed that DIBH significantly reduced cardiac irradiation without significantly affecting daily treatment times and that the extent of respiratory excursion in DIBH was associated with improved MHD. DIBH is a promising tool that is being rapidly incorporated into treatment for BC on the basis of several prior studies demonstrating its dosimetric advantages. For example, Comsa et al15 demonstrated significant improvements in MHD, heart V10, and heart V30 using DIBH with ABC and

References (27)

This study was funded by a research grant from Kaye Family New Technologies.

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