Significance of plasma thymosin alpha 1 measurements in gastric cancer patients

Thymosin al is a cleavage product of prothymosin alpha. Expression of proth ymosin a increases during cell proliferation. Thymosin alpha 1, measurable in plasma, may be an indicator of cell proliferation especially if a cancer is present. In this report we investigated the relation between the clinic al behavior of gastric cancer and the plasma thymosin alpha 1 level. Plasma thymosin alpha 1 was measured in 52 gastric cancer patients using a newly developed radioimmunoassay. Twenty-one tumors and lymph nodes were examined for thymosin alpha 1 using immunohistochemistry. The plasma thymosin alpha 1 level was higher in gastric cancer patients than in normal volunteers; a nd it was higher in patients with lymph node involvement than in those with negative nodes. Immunohistochemical study of thymosin alpha 1 showed posit ivity in 52% of gastric cancers and 100% of lymph node metastasis. We concl uded that a high level of plasma thymosin alpha 1 suggests aggressive behav ior of a gastric cancer, such as lymph node involvement.