Prognostic effect of stromal myofibroblasts in lung adenocarcinoma

Myofibroblasts are special cells with the features of both fibroblasts and smooth muscle cells, which are one of the most important cells in tumor stroma. The role of myofibroblasts in tumor stroma remains disputable. Some authors suggested that myofibroblasts can facilitate tumor progress, and another considered that myofibroblasts could prevent tumor cells diffusing. Bronchioloalveolar carcinoma (BAC) is a kind of adenocarcinoma in situ. With the destruction of the alveolar framework by tumor growth, BAC develops into mixed BAC and invasive adenocarcinoma, which is a natural model of transformation from carcinoma in situ to invasive carcinoma. In this study, the expression of myofibroblasts in BAC, mix-BAC and invasive adenocarcinoma was examined by immunohistochemical staining of surgical specimens from 102 patients. The results showed that positive expression of myofibroblasts in pure BAC (2/15, 13.33%) group was lower than in mix-BAC (17/38, 44.74%) and invasive adenocarcinoma (29/49, 59.18%) respectively, (p<0.05, p<0.01). In addition, myofibroblast positive expression was associated with lymph node metastasis, high stage, high grade, vascular invasion and shortened survival time in patients with lung adenocarcinoma. These data suggest that myofibroblasts are likely to facilitate the invasion and metastasis of the lung adenocarcinoma, and can be used as a prognostic marker. Myofibroblasts may become even a new target for treatment.