Using intensity-modulated radiotherapy to deliver an isotoxic treatment for non-small cell lung cancer patients allows doctors to give these patients an increased dose escalation, compared with three-dimensional conformal radiotherapy. These are the conclusions of a new study, led by researchers at the University of Manchester and The Christie NHS Foundation Trust, both part of the Manchester Cancer Research Centre.
The study, entitled “An Isotoxic Planning Comparison Study for Stage II–III Non-small Cell Lung Cancer: Is Intensity-modulated Radiotherapy the Answer?” and published in the journal Clinical Oncology, involved twenty patients with stage II/III non-small cell lung cancer.
In order to determine whether this novel radiotherapy technique could be used to increase the radiation dose to lung tumors without harming healthy organs, researchers made a dose-escalated plan for each of the patients, using three different methods: three to five beams of three-dimensional conformal radiotherapy, even beams of inverse-planned conformal radiotherapy, or seven beams of intensity-modulated radiotherapy.
The starting point for dose escalation was 55.8 grays (Gy) in 1.8 Gy per fraction twice a day. The team then increased the number of fractions until one or more organs exceeded their tolerance dose or a maximum dose of 79.2 Gy was reached.
Results showed that intensity-modulated radiotherapy allowed a significant dose increase in comparison with the other two methods, whereas no significant difference was found between three-dimensional conformal radiotherapy and inverse-planned conformal radiotherapy. Furthermore, the novel treatment was more successful in escalating doses in patients where the brachial plexus and spinal canal were close to the planning target volume. However, it did not allow the escalation of dose beyond 70.2 Gy due to the proximity of disease to the great vessels and the proximal bronchial tree.
According to Dr. Corinne Faivre-Finn, researcher at the University of Manchester and lead author of the study, the team estimates that intensity-modulated radiotherapy could yield a 10% improvement in tumor control. The team is now starting a new clinical trial, funded by Cancer Research UK, that will investigate the delivery of this personalized treatment in patients with non-small cell lung cancer.
“We hope to demonstrate that the increase dose delivered to the tumor will lead to improved survival,” she said in a press release.