A brief introduction to small cell lung cancer

Most people don’t know what small cell lung cancer is, and some have never even heard of it. In fact, small cell lung cancer is similar to cancer, but there are also differences. What specific disease is small cell lung cancer? Let us briefly introduce small cell lung cancer below.

Small cell lung cancer (SCLC) accounts for about 20% of lung cancer. It is highly malignant, has a short doubling time, and metastasizes early and extensively. It is sensitive to chemotherapy and radiotherapy, and has a high initial remission rate. However, it is very prone to secondary drug resistance and relapse. Systemic chemotherapy is the main treatment. Disease classification SCLC can be divided into small cell lung cancer (including the previous oat cell carcinoma) and mixed carcinoma (i.e., a mixed type of small cell carcinoma and squamous cell or adenocarcinoma). At present, the most commonly used staging system in the field of SCLC treatment is the SCLC staging system developed by the Lung Cancer Research Group of the Veterans Affairs Hospital in the United States: if the tumor is confined to one side of the chest cavity (including the regional lymph nodes it drains, such as the ipsilateral hilar, mediastinal or supraclavicular lymph nodes) and can be included in a radiotherapy field, it is limited stage (Limited Disease, LD); if the tumor exceeds the limited stage range, it is extensive stage (Extensive Disease, ED), of which the former accounts for about 1/3 and the latter accounts for 2/3. This staging method is simple and easy to use, and is related to treatment efficacy and prognosis. TNM staging is currently also used for SCLC staging.

It is generally believed that small cell lung cancer originates from Kulchitsky cells (argentophilic cells) in the bronchial mucosa or glandular epithelium and belongs to APUD (amine precursor uptake decarboxylation) tumors. Some people also believe that it originates from stem cells in the bronchial mucosal epithelium that can differentiate into neuroendocrine. Small cell lung cancer is the least differentiated and most malignant type of lung cancer. It often occurs in the central part of the lung, grows rapidly, and metastasizes early. Under a light microscope, the cancer cells are small and short spindle-shaped or lymphocyte-like, with little cytoplasm and a naked nucleus. Cancer cells are densely arranged in groups, separated by connective tissue, and sometimes cancer cells are arranged in groups around small blood vessels. Electron microscopic observation of ultrastructure shows that the tumor cell cytoplasm contains typical axon-like neuroendocrine granules, but the amount of granules varies, and it has been proven to be related to 5-HT and ACTH. From the immunohistochemical study, the tumor cells are positive for NSE, 5-HT, CgA, and some cases (10%) are positive for Sy, proving that small cell carcinoma has neuroendocrine function. In addition, positive immunohistochemical reactions for CK and EMA were simultaneously found in the same tumor.