Beta-2-microglobulin as a tumor marker in solid malignancies.

Beta-2-microglobulin (beta 2-MG) and CEA were measured in the sera of 186 cancer patients divided into two groups: at diagnosis (D) and at follow-up (F). Four groups of patients at diagnosis (D-I, D-II, D-III and D-IV according to TNM classification) and two at follow-up (in remission, F-RS, and in relapse, F-RP) were considered. All patients had normal serum creatinine and urea concentrations. beta 2-MG values in D-I were significantly (p less than 0.01) lower than those for D-II and D-III, while in D-IV they overlapped those of group D-I. No significant difference was observed between F-RS and F-RP patients. Patients with serum CEA concentration greater than 100 ng/ml revealed beta 2-MG values close to those of groups D-I and D-IV. In 10% of patients in stage IV or with CEA greater than 100 ng/ml beta 2-MG was lower than the mean value of the healthy population. From data beta 2-MG is probably produced by an aspecific reaction to the tumor and the decrease in advanced stages could express a decreased immunologic response. On the other hand, high serum beta 2-MG in the initial stages of the neoplasia may reflect an elevated cell turnover, while low beta 2-MG during the final stages may be due to a weak expression of the protein by highly undifferentiated cells.