Prognostic significance of histopathological parameters in resected squamous cell carcinomas of the lung

Lung cancer is a major cause of cancer-related deaths. Squamous cell carcinoma (SCC) constitutes 25-30% of all lung carcinomas and most patients are recognized in advanced stages. The use of personalized treatment methods in non-resectable or recurrent lung carcinomas is higher in adenocarcinomas than in SCC. Accepted histological features that can be used to predict prognosis in SCC are not yet available. Therefore, it is important to reveal morphological prognostic factors in lung SCC examination. In this study, we evaluated the haematoxylin&eosin (H&E)-stained and ki-67 immunohistochemical (IHC)-stained slides of 178 cases who were diagnosed SCC in the surgical materials between 2000 and 2016. Clinical features of patients with histological subtype, differentiation, tumor budding, spread through alveolar spaces (STAS), nuclear size, peritumoral stromal content and inflammatory cell infiltration, mitosis, lymphovascular invasion (LVI), perineural invasion (PNI), necrosis, pleural invasion, non-tumoral lung parenchymal characteristics and IHC ki-67 proliferation index were examined microscopically and the relationship of these findings with each other and survival was investigated. The mean age was 64.3 and 160 (89.9%) of the patients were male and 18 (10.1%) were female. 104 (58.4%) of the tumors were found in the central and 74 (41.6%) peripheral locations of the lungs. The mean tumor diameter was 3.8 cm. Hilar lymph node metastasis (LNM) was observed in 45 (30.4%) patients and mediastinal LNM was observed in 13 (9%) patients. According to pathologic TNM (pTNM) stage groups, 67 patients (40.9%) were stage I, 59 (36%) were stage II, 32 (19.5%) were stage III and 6 (3.7%) were stage IV patients. 128 (71.9%) of the tumors were moderately differentiated, 46 (25.8%) poorly differentiated and 4 (2.2%) were well differentiated tumors. According to the subtypes, 90 (50.6%) of the cases had nonkeratinizing, 85 (47.8%) had keratinizing, and three (1.7%) had basaloid histology. Tumor budding was detected in 67 (37.6%) of the tumors. According to the degree of budding, 31 patients (46.3%) in grade 1, 19 patients in grade 2 (28.4%), and 17 patients in grade 3 (25.4%) were recorded. STAS was seen in 79 (44.4%) of the tumors. In the grouping by nuclear size, 111 (62.4%) of the tumors featured medium-sized nuclei, 61 of them (34.3%) were large in size, and 6 (3.4%) of small-size nuclei. In 76 (42.7%) cases, fibrous stroma, 63 (35.4%) intermediate stroma and 39 (21.9%) fine stroma were detected. Peritumoral inflammatory cell infiltration was low in 64 (36%), moderate in 59 (33.1%), and high in 55 (30.9%). The mean number of mitotic count was found to be 21 in 10 high power field (HPF). While 118 (66.3%) of the cases had 10 or more mitosis in 10 HPF, in 60 cases (33.7%) mitotic count was less than 15 in 10 HPF. In 64 (36%) of the archival materials, IHC ki-67 stained slides were present and the mean ki-67 proliferation index was found to be 37.3%. LVI was observed in 91 (51.1%) patients, PNI in 15 (8.4%), necrosis in 112 (62.9%) and pleural invasion in 48 (27%) patients. In the evaluation of lung parenchyma adjacent to the tumor, no specific feature was found in 48 cases (27%). The mean survival time was 101.7 months. A significant relation was found between budding and LVI, PNI and peritumoral stroma, as well as the degree of budding and necrosis. STAS was associated with LVI, necrosis, and mitotic count. There is a significant relationship between nuclear size and peritumoral stroma, and pTNM stage. There was a statistically significant relationship between STAS and mitotic count. A significant relationship was found between median age of diagnosis, metastasis status and median survival with pTNM stage groups. There is still no accepted histologic features that can be used to predict the prognosis of lung SCC. The number of studies investigating the prognostic significance of SCC related histomorphological parameters is limited and yet the current and clear prognostic profile cannot be demonstrated. Therefore, we believe that this study will contribute to the determination of morphological features and prognostic factors that may affect the treatment decision in the future.