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 alpha and progesterone receptor were detected in only 1 and 14 cases, respectively. Estrogen receptor beta and aromatase were positive in 75 and 89 cases respectively. Estrogen receptor beta expression in non-small cell lung cancer showed an inverse correlation with lymph node metastasis (P < .05). Only among females, both estrogen receptor beta 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 beta, demonstrating a significant concordance (P < .05). Simultaneous immunohistochemical staining for aromatase and estrogen receptor beta showed a high rate of double positive association. Male non-small cell lung cancer cases with double positivity for aromatase and estrogen receptor beta 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 beta 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 beta in non-small cell lung cancer might suggest some functional correlation between aromatase and estrogen receptor beta, whereas estrogen receptor beta negativity might be correlated with malignant progression of non-small cell lung cancer.
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