BACKGROUND.The purpose of this study was to investigate whether tumor‐infiltrating immune cells in biopsy specimens can be used to predict the clinical outcome of stage IV nonsmall cell lung cancer (NSCLC) patients.METHOD.The authors performed an immunohistochemical study to identify and count the number of CD68+ macrophages, c‐kit+ mast cells, and CD8+ T cells in both cancer nests and cancer stroma in pretreatment biopsy specimens obtained from 199 patients with stage IV NSCLC treated by chemotherapy, and then analyzed for correlations between the number of immune cells and clinical outcome, including chemotherapy response and prognosis.RESULTS.There was no correlation between the number of immune cells in either cancer nests or stroma and chemotherapy response. Patients with more tumor‐infiltrating macrophages in cancer nests than in cancer stroma (macrophages, nests > stroma) had significantly better survival than nests < stroma cases median survival time (MST 440 days vs 199 days; P < .0001). Patients with more tumor‐infiltrating CD8+ T cells in cancer nests than in cancer stroma (CD8+ T cells: nests > stroma) showed significantly better survival than in nests < stroma cases (MST 388 days vs 256 days; P = .0070). The proportion of tumor‐infiltrating macrophages or CD8+ T cells between cancer nests and stroma became independent prognostic factors in the multivariate analysis. Neither the number of mast cells in nests nor in stroma correlated with the clinical outcome.CONCLUSIONS.Evaluation of the numbers of macrophages and CD8+ T cells in cancer nests and stroma are useful biomarkers for predicting the prognosis of stage IV NSCLC patients treated with chemotherapy, but could fail to predict chemotherapy response. Cancer 2008. © 2008 American Cancer Society.

Recent studies have reported increased podoplanin expression by cancer cells and stromal cells, but little is known about its expression and biological significance in adenocarcinoma of the lung. We examined podoplanin expression by both cancer cells and stromal cells in 177 consecutive lung adenocarcinoma cases and analyzed relations between podoplanin expression and both clinicopathological factors and outcome. Podoplanin expression was observed on the apical membrane of the cancer cells in only 9 of the 177 (5.1%) cases. By contrast, cancer-associated fibroblasts (CAFs) were found to express podoplanin in 54 cases (30.5%). Podoplanin (1) CAFs were found only in invasive adenocarcinoma and none were found in noninvasive adenocarcinoma. Conventional prognostic factors were significantly correlated with podoplanin expression by CAFs. The univariate analyses and log-rank test showed that podoplanin expression was significantly associated with shorter survival time (p < 0.001 and p < 0.001, respectively). We divided the cases into 3 groups according grade based on the proportion of CAFs expressing podoplanin [a grade 0 group (n 5 123), a grade 1 group (n 5 36) and a grade 2 group (n 5 18)]. The result showed that conventional prognostic factors were significantly correlated with the grade of podoplanin expression by CAFs. Furthermore, the grade 2 group tended to have a shorter survival time than the grade 1 group (p 5 0.092). The results of this study highlight the importance of podoplanin expression by CAFs and provide new insights into the biology of the cancer microenvironment in adenocarcinoma of the lung.

The latest World Health Organization (WHO) classification divides adenocarcinoma mainly into adenocarcinoma mixed subtypes, acinar adenocarcinoma, papillary adenocarcinoma, bronchioloalveolar carcinoma, and solid adenocarcinoma with mucin production, and it mentions several variants, including fetal adenocarcinoma, mucinous ("colloid") adenocarcinoma, mucinous cystadenocarcinoma, signet-ring adenocarcinoma, and clear cell adenocarcinoma. In general, the mucin-producing adenocarcinoma of the lung comprises signet-ring cell carcinoma (SRCC), solid adenocarcinoma with mucin production (SA), and mucinous bronchioloalveolar carcinoma (m-BAC), mucinous ("colloid") adenocarcinomas and/or mucinous cystadenocarcinoma, and mucoepidermoid carcinoma. As SRCC, SA, and m-BAC exhibit distinct clinical features, it is important to identify differences in their immunohistochemical characteristics to better understand their histogenesis. In this study we analysed SRCC, SA, m-BAC, normal lung, and foregut-related secretory tissue for immunohistochemical differences using tissue microarrays. SRCC and SA showed high expression of MUC1 (97.4% and 100%, respectively), cytokeratin (CK) 7 (both 100%), and thyroid transcription factor-1 (TTF-1) (81.1% and 100%, respectively). They also showed low expression of MUC5AC (25.5% and 21.1%, respectively) and MUC6 (18.3% and 10.5%, respectively), whereas m-BAC showed high expression of MUC5AC (97.5%), MUC6 (75.0%), and CK7 (94.7%), but low expression of MUC1 (57.5%), and TTF-1 (27.5%). Hierarchical clustering showed that the immunophenotypes of SRCC and SA belong to the same category as alveolar lining cells, whereas m-BAC clustered onto another branch with gastric foveolar cells and bronchial goblet cells. These immunohistochemical findings support the results of our previous clinicopathological analysis of SRCC of the lung showing that SRCC occurs anatomically in the peripheral portion of the lung rather than in the bronchial gland-bearing portion.

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