Background & objective: The conversion of androgen to estrogen is catalyzed by aromatase. Evidence to date indicates aromatase is the last rate-limited enzyme in this reaction. Previous studies have suggested that there is some imbalance and abnormality of sexual hormone of patients with lung cancer, but the reason is not clear yet. This study was designed to evaluate the relationship between level of sexual hormone of external blood and aromatase expression in cancer tissues of male patients with lung cancer.
Method: The levels of estradiol(E2) and testosterone(T) in plasma of external blood of 25 patients with lung cancer and 30 healthy men were measured by Enzyme Immunoassay Magnetic Solid Phase (IEMA). The protein expression of aromatase in 25 cancer tissues, 25 juxtacancerous tissues, and 11 tissues with benign lung disease were detected by Immunohistochemistry.
Results: The level of plasma E2 in external blood was significantly increased (P < 0.01) while T was significantly decreased (P < 0.01) in male patients with lung cancer. The expression of aromatase in about 52% lung cancer tissue samples was positive, but no aromatase expression in the juxtacancerous tissues and tissues with benign lung disease were found. The level of E2 had positive correlation to the expression of aromatase in male lung cancer patients(r = 0.9308, P < 0.001).
Conclusion: It is suggested that releasing of aromatase of lung cancer tissue, which catalyzes androgen to change into estrogen, into external blood might be the major reason of the increase of E2 and the decrease of T in external blood.