Stereotactic body radiotherapy (SBRT) has demonstrated an impressive 3-year control rate of higher than 90% for early stage NSCLC, leading to increased use of this technique as a curative method for lung cancer treatment. With growing clinical experience with this technique, post-SBRT follow up has received more attention. Follow up after SBRT is done primarily by thorax CT, which is affected by radiation-induced radiographic lung changes that can resemble or obscure local recurrence.
FLT (3'-deoxy-3'-fluorothymidine) is a thymidine analogue which is non-toxic in tracer doses, and can be labeled with 18F. FLT-PET is a type of imaging (similar concept to the widely used 18-FDG PET-CT) that is based on integration of thymidine into DNA for assessment of proliferation. Conceptually, increased DNA synthesis is correlated to tumor aggressiveness and response to therapy, more so than glucose utilization - as in FDG-PET could be.
The purpose of this study is therefore to see what added information the use of FTL-PET can provide in distinguishing between changes in the lung that occur as a result of treatment that are not cancerous and those that are due to recurrence or progressive disease.
