A Phase II Open-Label Multi-center Trial of Isotoxic Hypofractionated Radiotherapy for NSCLC

Radiotherapy plays an important role in non-small cell lung cancer (NSCLC), and concurrent chemoradiation is considered to be the standard treatment for locally advanced NSCLC. However, due to the patient's physical condition, comorbidities and other reasons, only about 1/3 of patients can receive concurrent chemoradiation. Radiotherapy alone or sequential chemoradiation has become the treatment protocol for most patients. Hypofractionated radiotherapy can be used in NSCLC because it can shorten the over treatment time and may potentially reduce the effect of accelerated repopulation and obtain higher biological effective dose（BED） So far, the vast majority of radiotherapy prescriptions have given a uniform dose of radiotherapy to all patients, regardless of individual factors such as tumor size, location, and adjacent vital organs, which may cause two consequences: First, small-volume tumors may, not receive enough radiation dose, resulting in a decrease in local control rates. Second, for large volumes of tumors or tumors adjacent to vital organs, even the "so-called standard dose" (60 Gy) may cause serious damage to normal tissues. This unified prescription dosage approach is completely inconsistent with the concept of precision treatment. The Netherlands MAASTRO put forward the concept of in silico radiotherapy prescription, that is: the normal tissue limits are uniform, such as: V20% ≤ 30%, spinal cord 0> 45Gy, etc., and each patient receives a different dose of radiation therapy. This radiation prescription could reach the limits of the normal tissue of every patient; if no one tissue limits were reached, the highest dose was set up to 79.2 Gy (1.8 Gy, BID). MAASTRO applied this "iso-toxic" radiotherapy prescription and used accelerated hyperfractionation technology so that each patient received the maximum individualized radiation dose as .From the model study to the long-term survival results, a series of encouraging results were achieved. The use of an individualized radiotherapy prescription based on iso-toxicity for the treatment of NSCLC in large-segment radiotherapy is expected to achieve: 1. For patients with small tumor volumes and no adjacent to vital organs, a higher radiation dose is given under safe conditions. 2. For patients with larger volumes of tumors or adjacent to vital organs, give safer doses.