Aldehyde dehydrogenase (ALDH) is a candidate marker for lung cancer cells with stem cell-like properties. Immunohistochemical staining of a large panel of primary non-small cell lung cancer (NSCLC) samples for ALDH1A1, ALDH3A1, and CD133 revealed a significant correlation between ALDH1A1 (but not ALDH3A1 or CD133) expression and poor prognosis in patients including those with stage I and N0 disease. Flow cytometric analysis of a panel of lung cancer cell lines and patient tumors revealed that most NSCLCs contain a subpopulation of cells with elevated ALDH activity, and that this activity is associated with ALDH1A1 expression. Isolated ALDH þ lung cancer cells were observed to be highly tumorigenic and clonogenic as well as capable of

Introduction We evaluated the ability of histopathologic response criteria to predict overall survival (OS) and disease-free survival (DFS) in patients with surgically resected non-small cell lung cancer (NSCLC) treated with or without neoadjuvant chemotherapy. Methods Tissue specimens from 358 patients with NSCLC were evaluated by pathologists blinded to the patient treatment and outcome. The surgical specimens were reviewed for various histopathologic features in the tumor including percentage of residual viable tumor cells, necrosis, and fibrosis. The relationship between the histopathologic findings and OS was assessed. Results The percentage of residual viable tumor cells and surgical pathologic stage were associated with OS and DFS in 192 patients with NSCLC receiving neoadjuvant chemotherapy in multivariate analysis (p = 0.005 and p = 0.01, respectively). There was no association of OS or DFS with percentage of viable tumor cells in 166 patients with NSCLC who did not receive neoadjuvant chemotherapy (p = 0.31 and p = 0.45, respectively). Long-term OS and DFS were significantly prolonged in patients who had ≤10% viable tumor compared with patients with >10% viable tumor cells (5 years OS, 85% versus 40%, p < 0.0001 and 5 years DFS, 78% versus 35%, p < 0.001). Conclusion The percentages of residual viable tumor cells predict OS and DFS in patients with resected NSCLC after neoadjuvant chemotherapy even when controlled for pathologic stage. Histopathologic assessment of resected specimens after neoadjuvant chemotherapy could potentially have a role in addition to pathologic stage in assessing prognosis, chemotherapy response, and the need for additional adjuvant therapies.

Purpose: To determine the frequency of estrogen receptor α and β and progesterone receptor protein immunohistochemical expression in a large set of non-small cell lung carcinoma (NSCLC) specimens and to compare our results with those for some of the same antibodies that have provided inconsistent results in previously published reports. Experimental Design: Using multiple antibodies, we investigated the immunohistochemical expression of estrogen receptors α and β and progesterone receptor in 317 NSCLCs placed in tissue microarrays and correlated their expression with patients' clinicopathologic characteristics and in adenocarcinomas with EGFR mutation status. Results: Estrogen receptors α and β were detected in the nucleus and cytoplasm of NSCLC cells; however, the frequency of expression (nucleus, 5-36% for α and 42-56% for β; cytoplasm: <1-42% for α and 20-98% for β) varied among the different antibodies tested. Progesterone receptor was expressed in the nuclei of malignant cells in 63% of the tumors. Estrogen receptor α nuclear expression significantly correlated with adenocarcinoma histology, female gender, and history of never smoking (P = 0.0048 to <0.0001). In NSCLC, higher cytoplasmic estrogen receptor α expression significantly correlated with worse recurrence-free survival (hazard ratio, 1.77; 95% confidence interval, 1.12, 2.82; P = 0.015) in multivariate analysis. In adenocarcinomas, estrogen receptor α expression correlated with EGFR mutation (P = 0.0029 to <0.0001). Estrogen receptor β and progesterone receptor but not estrogen receptor α expressed in the normal epithelium adjacent to lung adenocarcinomas. Conclusions: Estrogen receptor α and β expression distinguishes a subset of NSCLC that has defined clinicopathologic and genetic features. In lung adenocarcinoma, estrogen receptor α expression correlates with EGFR mutations. (Clin Cancer Res 2009;15(17): 5359-68) Lung cancer is the most common cause of cancer mortality worldwide, with >1 million deaths each year (1). Lung cancer includes several histologic types, the most frequently occurring of which are two types of non-small cell lung carcinoma (NSCLC): adenocarcinoma and squamous cell carcinoma (2). During the last two decades, mortality rates associated with cancer have continued to decrease across all major sites in men and women; however, the rates for lung cancer in females have continued to increase (3, 4). Despite global statistics estimating that 15% of lung cancer in men and 53% in women are not attributable to smoking (1), smoking remains the primary risk factor for lung cancer. The higher proportion of lung cancer in females who have never smoked compared with males who have never smoked suggests a possible role for gender-dependent hormones in the development of lung cancer (5).Estrogen receptors α and β are expressed in normal lung tissue and in lung tumors in men and women (6), yet the data are inconsistent about whether estrogen receptor expression is