Similarly, McFarland et al. (18) discovered that depressed patients with lung cancer possessed higher levels of proinflammatory cytokines compared with patients without depressive symptoms, which supports the contention that inflammatory cytokines, such as IL-6 and TNF-α, play a crucial role in the patients’ mood disorders by affecting the neurotransmitter metabolism, ultimately leading to abnormal neuroendocrine function. Here, TNF is linked to mood disorder.