Lung cancer is the most common cancer and the leading cause of cancer-related death worldwide [[1], [2], [3]]. Non-small cell lung cancer (NSCLC) accounts for 85 % of all lung cancers, with adenocarcinoma being the most common histologic type [3,4]. Despite the increasing advances in treatment, the prognosis of adenocarcinomas is still extremely poor.

Tumor budding (TB) was defined as an isolated single tumor cell or small clusters of tumor cells composed of less than five tumor cells that are branching from big tumor islands to the adjacent stroma [5]. It is thought to be a histomorphologic marker of an aggressive tumor behavior mimicking the epithelial-mesenchymal transition, and has been well established in the past two decades as a poor prognostic factor in many carcinomas, especially in colorectal carcinomas [[5], [6], [7], [8], [9]]. However, there are only a few studies about the significance of TB in lung adenocarcinoma.

Focal Adhesion Kinase (FAK) is a non-receptor cytoplasmic tyrosine kinase that plays a role in various cellular functions, including proliferation, survival, adhesion, migration and invasion. Because all of these processes are crucial for neoplastic transformation, FAK overexpression is seen in several cancers and is thought to contribute to the progression and metastasis of cancer [[10], [11], [12]]. Survivin is a family member of the inhibitor of apoptosis proteins (IAP). It inhibits apoptosis by binding specifically to the terminal affected cell death proteases, caspase 3 and 7, so high expression of survivin may protect cells from many apoptosis signals and help cells survive, especially cancer cells [[13], [14], [15], [16], [17]]. Therefore survivin expression has been investigated in many cancer types and emphasized that it may be an important factor both in the development of cancer and the prognosis of the tumor [[18], [19], [20], [21]].

The aim of this study was to investigate the ratio of TB, the expression of FAK and survivin, and their relationship with clinicopathological parameters, which may have prognostic importance in lung adenocarcinomas.