The risk of thromboembolism is elevated in lung cancer patients. The present project investigates whether stereotactic body radiation therapy (SBRT) further increases the risk of thromboembolic disease in lung cancer patients.

If coagulation is activated by SBRT, this study could form the basis of new clinical trials investigating whether lung cancer patients may benefit from thromboprophylaxis during and after stereotactic body radiation therapy.

In this study, the patients will have blood samples drawn three times (prior to start of stereotactic body radiation therapy, immediately after stereotactic body radiation therapy completion, four to six weeks after completing stereotactic body radiation therapy). The blood sample at the completion of stereotactic body radiation therapy is an extra compared to normal gathering of blood samples of patients with NSCLC treated with stereotactic body radiation therapy. Also extra glasses with blood will be gathered at each blood sample for storage in a biobank in order to be able to make future analysis on this material.

There is a minimal risk of developing infection or hematoma in connection with blood sampling but we consider this risk to be negligible. The total volume of 120 ml blood drawn over a period of 6 weeks is an inconsiderable risk for the patient.

Inclusion Criteria:

• Age > 18 years
• Planned stereotactic body radiation therapy of lung cancer

Exclusion Criteria:

• Inability to provide informed consent
• Venous thrombosis within the last three months
• Active cancer within the previous year except for lung cancer

A prospective study of 100 consecutively included lung cancer patients receiving stereotactic body radiation therapy. As standard treatment, which is considered for best practice, the patients receive:

1. 66 Gy/ 3 fractions (F) (new primary peripheral lung cancer), or
2. 50 Gy/ 5 F (new primary central lung cancer), or
3. 45 Gy/ 3 F (peripheral lung cancer relapse after initial surgery or stereotactic body radiation therapy)