TNF and squamous cell carcinoma: Studies in which authors were comparing the level of proinflammatory cytokines (TNF-α, IL-1a, IL-6 and IL-8) in saliva of patients with oral squamous cell carcinoma and patients with precancerous condition of the oral cavity as well as healthy patients, revealed an increased level of these cytokines in saliva of patients with squamous cell carcinoma.