Patients with breast cancer can be trained to achieve a breath hold lasting more than 5 minutes, allowing for targeted administration of radiotherapy with a single dose per daily session that can minimize damage to surrounding tissues.1
Usually, a beam of radiotherapy takes 2 minutes to administer. Shaped radiation beams from several different angles intersect at the tumor. Since patients breathe during this time, ventilator movement in the chest increases damage to surrounding healthy tissues.
Repeated breath holds of approximately 20 seconds can provide a stable target for the beam of radiotherapy, but the radiotherapy is administered over several doses.
This study showed that a single dose of radiotherapy could be administered stably with a single, prolonged breath hold.
“The physiology of breath holding is well understood on the whole, but has been somewhat overlooked in medical research because until now it hadn’t any obvious clinical application,” said Michael Parkes, MA, DPhil, senior lecturer in Applied Physiology, School of Sport, Exercise and Rehabilitation Sciences, the University of Birmingham, Birmingham, England, and first author of the study.
“Following on from our preliminary work on healthy subjects, we wanted to see if we could help patients with breast cancer to achieve a breath hold of over 2 minutes to allow a radiotherapy treatment to be delivered in a single breath hold.”
In this study, researchers safely trained 15 patients receiving radiotherapy for breast cancer to extend their breath holds. The training included instruction on how to maintain a relaxed posture and how to naturally raise blood oxygen levels and reduce carbon dioxide levels by preoxygenation and by mechanically induced hypocapnia.
Participants held their breaths for an average of 5.3 minutes, which is more than enough time for the 2 minutes needed for radiotherapy administration.
“Being able to hit the cancerous tumor accurately is essential to avoid damage to other areas, including the heart muscle. Having a stable chest that we can target in one dose could be invaluable in protecting the surrounding tissue,” said Parkes.
“Although 5 minute breath holds may seem astonishing to people, it is perfectly natural and safe for patients. Actually, anyone can do it. Patients are carefully monitored throughout the process, and if their oxygen levels drop or their blood pressure rises above a certain level, we would step in. The safety levels we use are very conservative so there is no risk attached.”
Two patients received Herceptin, and 13 received chemotherapy in addition to radiotherapy.
1. Parkes MJ, Green S, Stevens AM, Parveen S, Stephens R, Clutton-Brock TH. Safely prolonging single breath-holds to >5 minutes in cancer patients; feasibility and applications for radiotherapy [published online May 11, 2016]. Br J Radiol. doi:http://dx.doi.org/10.1259/bjr.20160194.