Lung cancer is not only the most common cause of cancer death, but also one of the most preventable, according to the Merck Manual, with 85 percent of lung cancers occurring in smokers or ex-smokers. Lung cancer accounts for around 30 percent of all cancer deaths each year in the United States, the American Cancer Society explains. Lung cancer mostly affects people over age 65, with two out of three people in that age group. There are different types of lung cancer, and the three most common include adenocarcinoma, squamous cell and small cell cancer of the lung.
Types
Adenocarcinoma, small cell and squamous cell are the most common types of lung cancer, and are classified according to the nature and origination of the cells. Adenocarcinoma and squamous cell lung cancers are non-small cell cancers. Adenocarcinoma arises from glandular lung tissue and often develops on the periphery, or outside parts, of the lungs, the College of American Pathologists explains. Around 60 to 80 percent of lung cancers in non-smokers are adenocarcinomas. Squamous cell carcinoma develops in the surface cells of the lungs and bronchi. Small cell cancer, also known as oat cell cancer, comprises 13 to 15 percent of all lung cancer and grows quickly and aggressively, Merck states.
Symptoms
The symptoms of all three major types of lung cancers include persistent cough, weight loss, loss of appetite, chest pain and weakness. Some people cough up blood, called hemoptysis. Adenocarcinomas may appear to be pneumonia or a collapsed lung, according to the College of American Pathologists. Symptoms vary depending on the location and spread of lung cancer, and may include chest pain, heart problems, hoarse voice, problems with the eyes, arm numbness, or difficulty swallowing.
Characteristics
Small cell cancers can spread through the bloodstream to the liver, brain or bones, causing symptoms in those areas before lung symptoms appear, complicating diagnosis, Merck states. Around 60 to 70 percent of people with small cell lung cancer have distant spread, or metastasis, at the time of diagnosis, Healthcommunities.com’s Oncology Channel reports. Non-small cell cancers spread more slowly.
Treatment
Because non-small cell cancers such as adenocarcinoma and squamous cell cancer often haven’t spread beyond the lungs at the time of diagnosis, surgical removal is often used to treat the tumors. Small cell cancers, which have usually spread beyond the lungs at the time of diagnosis, are treated with chemotherapy and radiation, the Oncology Channel reports.
Prognosis
Lung cancer in general has a poor prognosis, with an average survival time of six months for people with untreated advanced non-small cell cancer and a five-year survival rate of less than one percent for those with metastasized small cell or advanced non-small cell cancer, according to Merck. With early diagnosis and treatment, the five-year survival rate increases to 60 to 70 percent for non-small cell cancer.
