Session Item

To test the feasibility of Deep Inhalation Breath Hold (DIBH) to reduce radiation doses to the heart in patients with left sided breast cancer patients treated with radiotherapy in a multicentre prospective study. Patient reported outcomes such as anxiety associated with DIBH were also investigated in comparison to patients with right-sided breast cancer treated in free breathing (FB).

Patients with early stage breast cancer were enrolled from six radiotherapy centres with a range of experience in DIBH techniques in Australia and New Zealand. Participants with left-sided breast cancer were considered for breath holding during the delivery of radiotherapy following local protocol. Patients with right sided breast cancer were recruited in the same centres and treated in FB. Feasibility was multifactorial - defined as patients’ ability in breath holding for 15 seconds at a time, decrease in heart dose on the DIBH treatment plan compared to the FB plan of the patient without compromising other dosimetric requirements, and reproducibility of radiotherapy delivery using mid-lung distance (MLD) assessed on electronic portal imaging. Time required for treatment delivery in DIBH and FB was assessed in the first week as time from patient entering the room until delivery of the last field. Patient anxiety was rated using a visual analogue scale (VAS) anchored with “0: not at all anxious” to “10: extremely anxious” at simulation and daily before and after treatment during first and last weeks of radiotherapy (22 assessments total). 

Between February and November 2018, 32 left sided and 30 right-sided breast cancer patients were enrolled. As shown in figure 1, two left sided breast patients did not proceed to DIBH (one clinician and one patient decision). Planning comparison between FB and DIBH scans in left-sided breast cancer patients confirmed mean heart dose reduction from 2.8 to 1.5Gy (reduction 1.3Gy, 95% CI: 0.8-1.7, p < 0.001). Set-up reproducibility in the first week of treatment as judged by MLD measurement was 1.88 +/- 1.04mm (average +/- 1SD) for left (DIBH) and 1.59 +/- 0.93mm for right-sided patients. DIBH treatments took on average 2 minutes longer than FB treatments (14.6 +/- 3.1 and 12.5 +/- 4.3 min, respectively). Using a tight reproducibility cut-off for MLD of 2mm (1SD) DIBH was feasible for 67% of patients.

Anxiety decreased over the course of treatment in both groups (Figure 2). Scores were higher in DIBH patients at simulation and were comparable with the FB group thereafter. 

TROG 14.04 confirmed the reduction in mean heart dose using DIBH in patients with left sided breast cancer undergoing radiotherapy. Anxiety scores among DIBH patients suggested that breath holding or knowledge of the purpose of DIBH might increase patient anxiety.  Further research is needed regarding anxiety triggers and to improve set-up reproducibility.