The major problem in the management of cancer is the difficulty of an early diagnosis. Clinical signs and symptoms generally appear late in the course of the disease. The availability of a non-invasive test which detects a blood molecule closely associated with the malignant transformation of the cells could be of help in the early detection of cancer. Malignin is a 10 kDa polypeptide located in the cytoplasmic and outer membranes of all malignant cells. Anti-malignin antibodies (AMAs) are IgM immunoglobulins spontaneously produced by the host against the oncoprotein malignin when neoplastic transformation occurs; since AMAs are IgM, they can represent an "early" transformation indicator useful for the early detection of cancer. Elevated AMA serum concentrations, measured by means of TARGET@ reagent, have been demonstrated in patients with a wide spectrum of non-terminal active cancers, regardless of the anatomical site and histotype of the tumor. The AMA test showed a sensitivity and specificity of 95% on first determination and > 99% on repeated determinations, and has been reported to be a promising diagnostic tool for the early detection of cancer, as well as for monitoring of the response to treatment and possibly for screening of an asymptomatic population.