Lung cancer can be divided into two major categories, small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Small cell lung cancer has high growth activity and fast growth rate and is mainly treated by chemotherapy. Only small cell lung cancer with early stage 1 clinical diagnosis can be treated by surgical resection. Fortunately, small cell carcinoma only accounts for 20% of lung cancers. The greater chance of lung cancer is non-small cell lung cancer. In the early and middle stages of non-small cell lung cancer, surgery is encouraged to remove the diseased tissue first, and the post-surgical treatment plan will be formulated according to the above-mentioned pathological staging and the degree of lymph node invasion. In case of locally advanced stage, such as lymph node invasion, hilar invasion, invasion of large blood vessels, etc., a multidisciplinary approach is needed to discuss a reasonable treatment model by integrating medical, surgical, radiotherapy and imaging departments. Advances in molecular pathology-based diagnosis. Non-small cell lung cancer is subdivided into Adenocarcinoma, Squamous Cell Carcinoma, Mixed Adenocarcinoma, Large Cell Lung Cancer, and other rare lung cancers based on the differences in biological indicators observed. Each subtype of lung cancer is treated differently from one another. Adenocarcinoma and squamous carcinoma? Squamous and adenocarcinoma are not the only subtypes of lung cancer; they can also be found elsewhere. Adenocarcinoma of the lung is called squamous lung cancer because it occurs in the lungs. Squamous carcinoma is most often found in areas covered with squamous epithelium, such as the skin, mouth, and lips. Although the bronchi are not covered by squamous epithelium, the epithelial cells of the bronchi undergo squamous epithelial metaplasia, and immunohistochemical staining can be done under the microscope to see cancer cells like fish scales, which is called squamous carcinoma of the lung. (The picture below shows the morphology of cancer cells under microscope) Adenocarcinoma is a malignant tumor of salivary gland epithelium, usually in the alveoli, papillae, fine bronchi, and a few originate in the mucous glands of large bronchi. Under the microscope …… cancer cells do not look like lines, but are called adenocarcinoma because they are malignant tumors occurring in the epithelium of the salivary gland. Is adenocarcinoma of the lung caused by smoking? Early lung cancer studies at least two decades ago found different causative factors for different types of lung cancer. At that time, studies concluded that among lung cancer patients, heavy smokers were more likely to develop squamous carcinoma and nonsmokers were more likely to develop adenocarcinoma. However, as times have changed and industrialization has progressed, respirable particulate matter is finer and more likely to enter the terminal fine bronchi, the site of stimulation has changed, and the type of pathology has changed, so that smoking or not smoking is no longer directly linked to the type of lung cancer a patient has. Five years ago, the proportion of squamous lung cancer in medical textbooks was about 30-40% of lung cancer patients and adenocarcinoma of the lung was about 20%; however, the actual case statistics now show that adenocarcinoma of the lung accounts for 50% of lung cancer patients and squamous cancer accounts for about 10%, and adenocarcinoma of the lung also occurs in smokers. Nowadays, the proportion of patients with adenocarcinoma of the lung is increasing. Since statistics show that adenocarcinoma is more likely to occur in non-smokers and women, Asian women have a larger percentage of lung adenocarcinoma, and some believe it is related to the large amount of fumes inhaled by Asian women when cooking. This idea is still debated. It is evident that people are trying to break through the difficulties of cancer treatment, and cancer cells themselves are improving their survivability and cunningly circling with human beings. Which is better to treat, squamous cancer or adenocarcinoma? The ease of lung cancer treatment is still largely based on the size, location, and severity of invasion of the lesion – factors that influence the stage of the tumor. Earlier stage lung cancer will be relatively easy to treat, while advanced stage will be difficult to treat. There is also the issue of looking at genetic status and whether the patient has a mutation in a driver gene. Some mutations in driver genes may be the cause of tumor malignancy, and there are now some corresponding targeted therapeutic drugs. At present, the genetic profile of lung squamous carcinoma is not as well discovered as that of adenocarcinoma, and the inhibitory effect of molecularly targeted drugs is not as good as that of molecularly targeted drugs for lung adenocarcinoma. However, in the last two or three years, a newer treatment modality worldwide is immunotherapy, which is very effective for squamous lung cancer and is comparable to lung adenocarcinoma.