Lung Cancer: Signs, Symptoms, Types & Treatment

About 158,040 Americans are expected to die of lung cancer in 2015, according to the National Lung Association. From the time of diagnosis, between 11 and 15 percent of those afflicted with lung cancer will live beyond five years, depending upon demographic factors, according to the Environmental Protection Agency (EPA).

Causes

Smoking is the No. 1 cause of lung cancer, according to the American Lung Association. Even being near those who smoke can be dangerous. "Second-hand tobacco smoke exposure has been linked to lung cancer, with the extent of exposure determining the associated risk," said Dr. Megan Baumgart, an assistant professor in the department of medicine, hematology/oncology at the Wilmot Cancer Institute in Rochester, New York. "In general, people living in a home with a smoker or exposed to smoking in the workplace are at 20 to 30 percent increased risk of developing lung cancer compared to those who do not."

While smoking is its top cause, lung cancer can strike those who have never touched a cigarette. For example, radon, a radioactive gas found in homes and businesses, can cause lung cancer. In fact, radon is the No. 1 cause of lung cancer among non-smokers, according to the EPA. "Radon has been associated with an increase in risk for development of lung cancer, though this remains controversial. Other risk factors include prior radiation treatment to the chest or damage to the lungs from an underlying inflammatory pulmonary disease such as pulmonary fibrosis or alpha-1 antitrypsin deficiency," Baumgart said.

Other culprits may be air pollution and inflammation. "There’s been lots of research of late indicating that people are developing non-smoking related lung cancer with frightening increased incidence," Dr. Mitchell Gaynor, an oncologist in New York City and author of "The Gene Therapy Plan" (Viking, 2015), told Live Science.

"This could be caused by pollution coupled with the body’s inability to detoxify these carcinogens," he said. "Inflammation turns on tumor-promoting genes and increases insulin-like growth factor, interleukin six, and activating protein one, all of which promote the development of lung cancer. The major promoters of inflammation and obesity are white bread and sugar laden diets common in America."

Genetics may also play a role in the development of lung cancer, according to the National Cancer Institute (NCI). "The role of genetics and family history in the development of lung cancer is not well understood, but the risk appears highest for those with relatives diagnosed at a young age and in those with multiple family members diagnosed with lung cancer,” Baumgart said.

Types of lung cancer

Lung cancer, also called pulmonary carcinoma, is divided into three main categories. Non-small cell lung cancer is a variety that encompasses several similar sub-types, including adenocarcinoma, squamous cell carcinoma and large cell carcinoma. This type is the most common, accounting for 85 percent of lung cancers, according to the American Cancer Society (ACS). Small cell lung cancer comprises about 10 percent to 15 percent of all cases and is a fast-growing form of lung cancer, according to the ACS. Lung carcinoid tumors are rare, grow very slowly and usually do not spread.

Cases that include both main types are called mixed small cell/large cell lung cancer, according to the National Institutes of Health (NIH).

Additionally, a highly lethal form of cancer called mesothelioma most often arises in the tissue surrounding the lungs. Mesothelioma primarily afflicts those who have been exposed to asbestos, a mineral used in insulation, brakes, flooring and many other goods

Symptoms and signs

Early lung cancer is usually symptomless, according to the Mayo Clinic. Lung cancer symptoms also resemble those of many other conditions, making it hard to discern the cause. 

As the condition progresses, certain symptoms may arise. According to the Cleveland Clinic, these symptoms include:

• Persistent, prolonged cough
• Coughing up blood
• Wheezing and shortness of breath
• Chest pain
• Appetite loss
• Hoarseness
• Unexplainable weight loss
• Fatigue or weakness
• Difficulty swallowing

Diagnosis and tests

Using a stethoscope, doctors sometimes can hear fluid around the lungs, which may suggest lung cancer. But definitively diagnosing it usually involves a combination of several tests, according to the ACS. These include:

• Imaging tests such X-rays, positron emission tomography (PET) scans, CT scans or MRI scans of the chest.
• Sputum test, which examines coughing-induced phlegm for abnormal cells.
• Biopsy, which examines cells from one or more procedures that retrieve a tissue sample.
• Bronchoscopy: The bronchi, or tubes leading into the lungs, can be viewed through an instrument called a bronchoscope, allowing doctors to see abnormal areas, according to the Cleveland Clinic. Suspicious cells can be taken for biopsy.
• Mediastinoscopy: A lighted tube is inserted above the breast bone through a small incision to see the center of the chest cavity.