A new 4-dimensional software program promises to improve the treatment of lung cancer by allowing doctors to take the movement of breathing into account when administering radiotherapy, researchers announced today at the 2nd European Lung Cancer Conference in Geneva, Switzerland.
Some lung tumors shift their position as patients inhale and exhale. The amount of movement depends on where they are in the lung. For example, lesions in the lower lobes may move up to 4 cm.
This movement poses a challenge for doctors treating the cancer with radiotherapy. If they use too small an irradiation field, the tumor can move so far that it is missed by the treatment. To avoid this, standard radiotherapy uses large radiation fields to take into account the respiratory movements, but in doing so can damage large areas of healthy lung tissue.
A newer approach, called 'breathing-adapted radiotherapy' (BART) allows doctors to reduce the amount of radiation delivered, and improve the chance of hitting the tumor, by timing delivery to a particular moment of the respiratory cycle.
"One of the main problems with BART is how to choose the optimal respiratory phase in which to treat the patient," explains Dr Nicolas Peguret from Hpitau Universitaires de Genve. "This phase is basically unknown and may be in deep inspiration, in expiration or even in a third respiratory phase somewhere between. It may vary from one patient to another because of the variation in tumor localization and in movements of the tumor and of other nearby organs."
Dr Peguret and colleagues have developed software which allows doctors to determine a moment during the respiratory cycle with an optimal tumor position for radiotherapy. "By applying this software together with BART, it may be possible not only to reduce the radiation fields but also to adapt the radiation volume taking into account the varying positions of the tumor and the organs at risk."
|Contact: Vanessa Pavinato|
European Society for Medical Oncology