- Recent converging evidence suggests that the brain may receive stimuli and possibly modulate tumor progression via the vagus nerve. The present study aimed to compare brain metabolism in patients with and without lung cancer and to assess if significant differences exist in regions associated with the vagus nerve. Eighteen patients with lung malignancy and 19 controls underwent (18)F-FDG PET of the brain. Brain metabolism was compared using statistical parametric mapping. Patients with lung malignancy showed a statistically significantly higher right cerebellar metabolism. This finding may be related to the role of the cerebellum in immune regulation, because of its proximity to the nucleus tractus solitarius innervated by the vagus and its connections with the hypothalamus. This higher metabolism in the right cerebellum may reflect an attempt to reinstate homeostasis in functions such as respiration and immunity pertinent to lung malignancy.