Safety Study of Individualised Radiation Dose Determination for Lung Cancer Patients.

Radiotherapy is treatment of choice for inoperable lung cancer. Research has shown that the survival rate as well as the local control rate is low. If chemotherapy treatment is added it leads to a slightly better outcome. The radiotherapy treatment often causes pneumonitis and/or esophagitis. So damage to the normal tissue restricts the radiation dose that can be administered. However, several studies have shown that higher doses lead to better local control. Furthermore it is evident that the radiotherapy treatment should be given in a short time, preferably the treatment time should not exceed 32 days. To avoid a higher toxicity the normal tissue has to be spared, but to increase the local control rate the tumor dose must be as high as possible. This dilemma can only be solved by using very sophisticated treatment planning techniques in combination with a biologically superior treatment schedule. This schedule consists of delivering radiation dose twice a day instead of once, thus keeping the overall treatment time as low as possible. For the whole patient population, the mean lung dose can to a great extend predict the probability for developing radiation pneumonitis and the post-radiotherapy lung function. A logical next step is to determine the dose of radiotherapy on an individualised calculation of the maximum tolerated dose, being defined as the mean lung dose and the spinal cord dose. The objective of this trial is to investigate whether individualised radiation dose calculation based on a mean lung dose and the constraints of the spinal cord, in combination with an overall treatment time of less than 32 days, and only irradiating the primary tumor and the PET scan positive mediastinal areas is safe.