Do you know about small cell lung cancer

Small cell lung cancer is a type of bronchial lung cancer with symptoms similar to those of common cancers. But do you know about small cell lung cancer? Do you know the medical knowledge about the cause, symptoms, clinical manifestations, treatment methods and drugs of this disease? Let me show you how to learn about small cell lung cancer.

What is Small Cell Lung Cancer

Small cell lung cancer, also known as small cell undifferentiated carcinoma, is the most malignant type of lung cancer, accounting for about 1/5 of primary lung cancers. Patients with this disease are generally young, mostly around 40-50 years old, and most have a history of smoking. The rate of male patients is higher than that of female patients. Cancer cells often invade the extra-pulmonary parenchyma and easily merge with the hilar and mediastinal lymph nodes to form masses. Cancer cells grow fast, have strong invasiveness, and metastasize to distant organs early, often to the brain, liver, bones, adrenal glands and other organs. This type of lung cancer is more sensitive to radiotherapy and chemotherapy.

Disease classification

Pathologically, SCLC can be divided into: small cell lung cancer (including the previous oat cell carcinoma) and mixed carcinoma (i.e. a mixture of small cell carcinoma and squamous cell carcinoma or adenocarcinoma).

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 of the United States: if the tumor is confined to one side of the chest cavity (including the regional lymph nodes draining from it, 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. The TNM staging is currently also used for the staging of SCLC.

Small cell lung cancer causes

Smoking is the main risk factor for lung cancer, and SCLC is closely related to smoking. According to a summary analysis of smoking and lung cancer worldwide from 1970 to 1999, lung cancer is positively correlated with smoking intensity (amount of smoking) and duration, and the relationship with SCLC is most obvious.

Pathogenesis of small cell lung cancer

In the past few decades, there have been many studies on the molecular mechanism of SCLC, suggesting that the occurrence of SCLC may involve the participation of multiple genes. Some studies have shown that the tumor suppressor gene p53, RB gene (neuroblastoma gene), oncogene Bcl-2 gene, Myc gene, PI3K/AKT/mTOR signal transduction pathway, etc. are all related to the occurrence of SCLC.

Pathophysiology of small cell lung cancer

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, tumor cells are positive for NSE, 5-HT, CgA, and some cases 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.