Optimizing (breathing) techniques for radiotherapy of esophageal and lung carcinomas; a pilot study.

Neo-adjuvant chemoradiotherapy (neo-CRT) is increasingly applied in the
curative treatment of esophageal cancer, with the aim to downstage the tumor,
to increase the rate of radical resections, and consequently to improve the
survival rates. Due to improved survival, it will become increasingly important
to minimize the radiation-induced toxicity among long-term survivors.
In the management of locally advanced non small cell lung cancer (NSCLC),
radiotherapy is the standard treatment modality. However, the dose that can be
safely applied to the tumour is limited by the risk of cardiac and pulmonary
complications, which even led to decreased survival in a randomised study, when
a higher tumor dose was administered [1].
Radiation induced pulmonary and cardiac toxicity are the most important late
side effects after thoracic radiotherapy [2-4].
The aim of this study is to reduce the radiation dose of heart (and lungs) in
order to reduce the toxicity risk.

In recent years, the active breathing control (ABC) technique has been
introduced in the radiotherapy for left sided breast cancer patients, to
minimize the radiation dose to the heart. These patients are irradiated in the
inspiration phase, in which the distance between the heart and the breast is
largest, while the lungs extend.
Breath hold might also be beneficial for radiotherapy of esophageal and lung
tumors. For these patients the expiratory phase might theoretically be more
beneficial to reduce the heart dose. However, the inspiration phase might be
better for the dose to the lungs, which consequently allows cardiac dose
reduction.
In a very recently published study, favorable radiotherapy planning parameters
(tumor motion; mean lung dose, mean heart dose) were achieved using continuous
positive airway pressure (CPAP) in the treatment of lung tumours [6]. CPAP is
routinely used by patients at home during the night for treatment of
obstructive sleep apnea. In that study it was shown to be feasible for
radiotherapy planning as well as treatment itself. However, CPAP-supported
radiotherapy was not compared with any breath-hold techniques in that study

Primary objective:
To determine the optimal breathing technique to minimize the dose to the heart
of radiotherapy for esophageal and lung cancer using current photon techniques,
without compromising the dose to the lungs.

Secondary Objectives:
1. To investigate the differences in dose distribution using the different
breathing techniques (CPAP vs. ABC in inspiration, expiration) for 3D-CRT, IMRT
and proton radiotherapy.
2. To investigated the effect on the ITV margin (ITV minus GTV) and on the dose
distribution to the planning target, heart and lungs.
3. To evaluated the relationship between cardiac and pulmonary dose parameters
using different breathing and radiotherapy techniques.

This is an in silico planning comparative study.

Active Breathing Controle

Participation in this study does not involve any additional risk to patients,
besides the risk incurred by additional CT-scans. Patients will undergo a free
breathing 4D planning-CT (including spiral CT) combined with 3 additional CT*s
in inspiration breath-hold and in expiration breath-hold and a 4D-CT using
CPAP. The additional radiation dose of the 3 extra CT*s is extremely low
compared to the radiation dose of the treatment. The risks are therefore
negligible and the burden is low.