The Effect of Carbogen Breathing on 18F-FDG Uptake in Non-Small-Cell Lung Cancer

Abstract EN

It has been reported that 18F-FDG uptake is higher in hypoxic cancer cells than in well-oxygenated cells.

We demonstrated that 18F-FDG uptake in lung cancer would be affected by high concentration oxygen breathing.

Methods.

Overnight fasted non-small-cell lung cancer A549 subcutaneous (s.c.) xenografts bearing mice (n = 10) underwent 18F-FDG micro-PET scans, animals breathed room air on day 1, and same animals breathed carbogen (95% O2 + 5% CO2) on the subsequent day.

In separated studies, autoradiography and immunohistochemical staining visualization of frozen section of A549 s.c.

tumors were applied, and to compare between carbogen-breathing mice and those with air breathing, a combination of 18F-FDG and hypoxia marker pimonidazole was injected 1 h before animal sacrifice, and 18F-FDG accumulation was compared with pimonidazole binding and glucose transporter 1 (GLUT-1) expression.

Results.

PET studies revealed that tumor 18F-FDG uptake was significantly decreased in carbogen-breathing mice than those with air breathing (P<0.05).

Ex vivo studies confirmed that carbogen breathing significantly decreased hypoxic fraction detected by pimonidazole staining, referring to GLUT-1 expression, and significantly decreased 18F-FDG accumulation in tumors.

Conclusions.

High concentration of O2 breathing during 18F-FDG uptake phase significantly decreases 18F-FDG uptake in non-small-cell lung cancer A549 xenografts growing in mice.