Tumor associated antigens, which are produced specifically by tumor cells, are promising targets for the early diagnosis and immunotherapy. Among the tumor associated antigens, MAGE (a melanoma antigen), BAGE, GAGE, PRAME and NY-ESO were named as cancer/testis specific antigens since they are detected exclusively in the testis or cancer cells. If MAGE is easily detectable in the sputum, it would become a convenient method for diagnosing lung cancer. This study was undertaken to investigate MAGE expression in the induced sputum obtained from lung cancer patients.

In 14 control patients and 30 lung cancer patients, the induced sputum was collected after inhaling 3% saline(5 cc) delivered by nebulizer for approximately 5 minutes after a mouth rinse and bronchodilator inhalation. The induced sputum was placed in a conservative-mixed solution (guanidinium isothiocyanate, Triton X-100). The total cellular mRNA was extracted from the cells and RT PCR and nested PCR were run in 30 and 35 cycles respectively, with two different types of primers specially designed to detect six subtypes of MAGE DNA simultaneously.

MAGE expression was not detected in the 14 controls, but in the 30 cancer patients, MAGE was found in 24 patients (80%, p=0.001). In the cancer patients, there were no differences in the expression level according to the tissue types (squamous cell cancer 13/17, adenocarcinoma 7/9, and small cell cancer 4/4, p=0.56). Among the 24 MAGE-positive patients, the tumor was not visible on a bronchoscopy in 11 patients (45.8%).

A study of MAGE in induced sputum appears to be a useful and complementary method in the diagnosis of lung cancer. A further prospective study with more patients is recommended.