A PET tracer--3'-deoxy-3'-(18) F-fluorothymidine ( F-FLT)--could monitor changes in cellular proliferation of non-small-cell lung cancer (NSCLC) during radical chemo-radiotherapy, according to research published April 20 in the online edition of International Journal of Radiation Oncology, Biology, Physics.
Michael MacManus MD, from the division of radiation oncology at Peter MacCallum Cancer Centre in East Melbourne, Victoria, Australia, and colleagues noted that this proof of concept study indicated the usefulness of 18F-FLT as a tracer in developing response-adapted radiotherapy for NSCLC.
As part of a prospective pilot study, five patients with locally advanced NSCLC underwent serial 18F-FLT PET/CT scans during treatment on days 2, 8, 15 or 29.
The researchers compared baseline 18F-FLT PET/CT scans with routine staging 18F-FDG PET/CT scans. They observed 18F-FLT uptake in tumor on five of nine (55 percent) on-treatment scans, on days 2, 8 and 29, but not day 15.
“A marked reduction of 18F-FLT uptake in irradiated bone marrow was observed for all cases. This reduction was observed even after only 2 Gray (Gy), and all patients demonstrated a complete absence of proliferating marrow after 10 Gy,” the researchers wrote.
The team concluded that 18F-FLT uptake can monitor the distinctive biologic responses of epithelial cancers and highly radiosensitive normal tissue changes during radical chemo-radiotherapy.