Isotoxic Intensity Modulated Radiotherapy (IMRT) in Stage III Non Small Cell Lung Cancer (NSCLC) - A Feasibility Study (Isotoxic-IMRT)

Background:

Approximately 12,000 patients are diagnosed with stage III NSCLC in the UK each year and their survival is ~15% at 5 years. As the majority of patients are not suitable for the gold standard treatment (concurrent chemo-radiotherapy (CTRT), novel strategies integrating radiotherapy (RT) technological advances and radiobiological knowledge need to be evaluated in patients treated with the alternative treatment option, sequential CTRT. There is solid evidence that improving local control in lung cancer leads to increased survival. Strategies to improve local control in stage III NSCLC include dose escalation and individualisation which are limited by the dose delivered to surrounding normal tissues. We hypothesise that this will be facilitated by the use of IMRT.

Objectives:

To demonstrate the feasibility of delivering isotoxic RT using IMRT and hyperfractionated accelerated RT in stage III NSCLC patients who are not suitable for concurrent CTRT.

Endpoints:

Primary endpoint: Delivery of isotoxic IMRT to dose >60 Gy EQD2 (total biologically equivalent in 2 Gy fraction).

Secondary endpoints: Estimation of the suitability for lung isotoxic IMRT, estimation of proportion of patients with acute grade 3+ non haematological toxicity, estimation of late toxicity, estimation of local control/overall survival and development of a robust Quality Assurance (QA) process for lung IMRT.

Design:

Prospective multicentre, non-randomised feasibility study with early stopping rules.

35 patients will be recruited in this prospective multicentre feasibility study. Stopping rules are in place to ensure the safety of patients. We estimate that this regimen would be of added value to a national randomised phase II trial if 80% of the patients can be planned to a dose >60 Gy EQD2.

Intervention:

Patients with stage III NSCLC, PS 0-2, not suitable for concurrent CTRT, will be treated with individualised doses of radiation based on pre-specified normal tissue doses (spinal cord, brachial plexus, lung tissue, heart and great vessels/proximal bronchial tree). Radiotherapy will be delivered twice-daily over a maximum period of 4.5 weeks using IMRT and the dose of radiation will be increased until one or more of the organs at risk tolerance or the maximum dose of 79.2 Gy is reached.