What is Lung Cancer?
Lung cancer, also known as lung carcinoma, is a malignant tumor that begins in the lung. It is caused by genetic damage to the DNA of cells in the airways, often due to cigarette smoking or inhaling harmful chemicals. Damaged airway cells gain the ability to multiply unchecked, leading to the growth of tumors. Without treatment, tumors spread throughout the lung, impairing lung function. Eventually, lung tumors can metastasize, spreading to other parts of the body.
Symptoms of Lung Cancer
Early lung cancer often shows no symptoms and can only be detected through medical imaging. As the cancer progresses, most people experience nonspecific respiratory problems such as coughing, shortness of breath, or chest pain. The symptoms can vary depending on the tumor's location and size. If lung cancer is suspected, patients typically undergo a series of imaging tests to determine the location and extent of the tumor.
A definitive diagnosis requires a biopsy of the suspected tumor, which is then examined by a pathologist under a microscope. The pathologist can classify the tumor according to the type of cells it originates from. Around 15% of cases are small-cell lung cancer (SCLC), and the remaining 85% are non-small-cell lung cancers (NSCLC), which include adenocarcinomas, squamous-cell carcinomas, and large-cell carcinomas. After diagnosis, further imaging and biopsies are performed to determine the cancer's stage based on how far it has spread.
Treatment for Lung Cancer
Treatment for early-stage lung cancer typically involves surgery to remove the tumor, followed by radiation therapy and chemotherapy to destroy any remaining cancer cells. In later stages, cancer is treated with radiation therapy, chemotherapy, and drug treatments that target specific cancer subtypes. Despite treatment, only around 20% of people survive five years post-diagnosis. Survival rates are higher in those diagnosed at an earlier stage, younger age, and in women compared to men.
Prevention of Lung Cancer
Most lung cancer cases are caused by tobacco smoking, while the remaining cases are linked to exposure to hazardous substances like asbestos and radon gas, or to random genetic mutations. Prevention efforts emphasize avoiding hazardous chemicals and quitting smoking, both of which can reduce the risk of developing lung cancer and improve treatment outcomes in those already diagnosed.
Statistics
Lung cancer is the most diagnosed and deadliest cancer worldwide, with 2.2 million cases in 2020 resulting in 1.8 million deaths. The disease is rare in people under 40, with an average diagnosis age of 70 years and an average death age of 72. Incidence and outcomes vary significantly across the world, often depending on smoking patterns. Before the widespread adoption of cigarette smoking in the 20th century, lung cancer was a rare disease. In the 1950s and 1960s, mounting evidence linked lung cancer with tobacco use, leading to widespread campaigns against smoking by national health bodies.