SCLCs, which make up about 10 percent of all lung cancers, are highly aggressive and spread rapidly to regional lymph nodes and submucous membranes. Large cell anaplastic carcinomas (NSCLC-NOS), on the other hand, are more proximal in location and advance through local invasion of juxta-opposed structures. The stage of the disease depends on the presence of cancer cells in the airway. For instance, stage 0 indicates the presence of cancer cells only in the airways. In contrast, stage 1 describes a tumor that is at least four centimeters in size but has not spread to other parts of the body.
Some people inherit mutations in their DNA from their parents, which increase the risk of some types of cancer. But most lung cancers do not carry such mutations. Nevertheless, studies suggest that some families with a history of lung cancer may have genes that increase the risk of lung cancer. People with changes in chromosome 6 are more prone to develop lung cancer, even if they do not smoke. Inherited genes may also cause a person to have a reduced ability to break down cancer-causing chemicals and remove tobacco smoke.
Some lung tumours produce hormone-like substances that enter the bloodstream. These substances affect other organs and tissues in the body. These symptoms are known as paraneoplastic syndromes. Despite being specific to lung cancer, they are often mistaken for other illnesses, such as diabetes. A common symptom is pleural effusion, a buildup of excess fluid that collects in the lung. Cancer cells are found in this fluid, which is called malignant pleural effusion.
Early diagnosis of lung cancer is crucial for beating the disease. A doctor can examine a suspicious mass in the lung by X-ray or CT scan. A biopsy will confirm the diagnosis. If caught early, most lung cancer is curable. Surgery is used to remove stage I cancer. Radiation therapy and chemotherapy may also be necessary. However, lung cancer can progress to stage II, where it can spread throughout the body and affect the quality of life.
The five-year survival rate varies depending on the stage and subtype of the disease. The most common type of lung cancer is non-small cell, which makes up 85 percent of all cases. Non-small cell lung cancers include adenocarcinoma, lung squamous cell carcinoma, and large cell carcinoma. Although the survival rate of patients with non-small cell lung cancer depends on the type and stage of the disease, it is significantly higher than that of patients with small cell lung cancer.
There are several targetable genetic alterations in lung cancer. These include activating mutations of proto-oncogenes such as EGFR and ALK, which are involved in apoptosis and proliferation. Another type of targetable genetic alterations is the overexpression of certain oncogenic genes by microRNAs, or TSG, such as TP53. And finally, there are TSGs such as TP53, CDKN2A, and RASSF1A.
