Highly concordant coexpression of aromatase and estrogen receptor β in non–small cell lung cancer☆

Estrogen receptor expression has been reported in non–small cell lung cancer. We examined the correlation between aromatase, a key enzyme in the synthesis of estrogen, and estrogen receptor expressions in 105 non–small cell lung cancer cases. All patients were older than 60 years, and all female patients were postmenopausal. Estrogen receptor α and progesterone receptor were detected in only 1 and 14 cases, respectively. Estrogen receptor β and aromatase were positive in 75 and 89 cases respectively. Estrogen receptor β expression in non–small cell lung cancer showed an inverse correlation with lymph node metastasis (P < .05). Only among females, both estrogen receptor β and aromatase expressions were correlated with higher Ki-67 labeling index and younger age (P < .05). Among 89 aromatase-positive cases, 70 were positive for estrogen receptor β, demonstrating a significant concordance (P < .05). Simultaneous immunohistochemical staining for aromatase and estrogen receptor β showed a high rate of double positive association. Male non–small cell lung cancer cases with double positivity for aromatase and estrogen receptor β demonstrated lower status in N factor by TNM classification (P < .05). In addition, among 89 aromatase-positive cases, a low-Allred total score of estrogen receptor β showed a significant relationship with large tumor size and high T factor by TNM classification (P < .05). In conclusion, frequent coexpression of aromatase and estrogen receptor β in non–small cell lung cancer might suggest some functional correlation between aromatase and estrogen receptor β, whereas estrogen receptor β negativity might be correlated with malignant progression of non–small cell lung cancer.