Lung cancer is the third most common cancer in America. Although it affects fewer people than skin cancer, breast cancer, and prostate cancer, it kills twice as many as all three combined. Lung cancer is responsible for over 10 percent of new cancer diagnoses and 27 percent of all cancer deaths. More than 220,000 people are diagnosed with it every year.
Lung cancer normally starts in the structures that deliver oxygen from the air into the blood cells: bronchi (main airway), the bronchioles (branching airways), and the alveoli (air sacs). The primary causes of lung cancer are natural mutations brought on by the aging process, environmental hazards, and unhealthy habits, such as smoking. Individuals at high risk for developing lung cancer, particularly smokers, should learn about lung cancer screening and the steps they can take to reduce their risk.
Lung Cancer Types
There are three types of lung cancer: non-small cell, small cell, and carcinoid tumors. Each type grows and spreads differently, and requires different treatment.
Non-Small Cell Lung Cancer
Non-small cell lung cancer (NSCL) is the most common type of lung cancer, making up 85-90 percent of all reported cases. The leading cause of NSCL is smoking, followed by radon exposure and genetics. It is also the most common type of lung cancer in women, non-smokers, and young adults. Having a first-degree relative (mother, father, brother, sister) with lung cancer doubles a person’s risk. Doctors divide NSCL into three sub-categories: adenocarcinoma, squamous carcinoma, and large-cell carcinoma.
Adenocarcinomas form in the outer layers of the lungs and are the most common type of NSCL. They’re responsible for approximately 40 percent of all lung cancers in America and are becoming more common in women, non-smokers, and people under 45, though doctors are not certain why.
Squamous carcinomas form in the central areas of the lungs, normally around the large bronchi connected to the trachea. Squamous carcinoma is more common in men than in women and, because it grows slowly, it is normally detected while it’s still in its early stages.
Large-cell carcinomas form in the outer areas of the lungs. They appear very large and round when examined under a microscope, hence their name. Large-cell carcinomas grow rapidly and spread quickly to other organs.
Small Cell Lung Cancer
Approximately 10 to 15 percent of lung cancers are small cell lung cancers (SCLC). SCLC normally begin in the bronchi near the center of the chest and grow rapidly. There are two types of SCLC: limited and extensive. Limited SCLCs are confined to the lungs, nearby lymph nodes, or the space between the lungs (the mediastinum). Extensive SCLCs have spread to other organs, such as the brain, liver, or bones.
Lung Carcinoid Tumors
Lung carcinoid tumors begin in the neuroendocrine system, a diffuse collection of cells that produce hormones in response to neural signals. Lung carcinoid tumors are rare. They also grow more slowly and are less likely to spread than other types of lung cancer.
Doctors also divide lung cancer into two further categories: primary and secondary. Primary lung cancers are tumors in the lungs. Secondary lung cancers are tumors that metastasize and spread to new organs.
Lung Cancer Symptoms
Lung cancer symptoms are often undetected during their early stages because they are similar to symptoms caused by congestion and other diseases like pneumonia. However, it’s important that everyone be able to identify the symptoms of lung cancer. Lung cancer affects everyone, even non-smokers, and knowing when to go to a doctor may be the difference between life and death. Lung cancer treatments are most effective when the disease is still in its early stages. The most common signs of lung cancer are:
Persistent coughing is the most common lung cancer symptom. The cough may be wet or dry, frequent or infrequent, but if it persists for more than a few weeks, it may be a sign of serious illness. Only two percent of people with persistent coughs have lung cancer, but 50 percent of people with lung cancer have a persistent cough.
Shortness of Breath
In most people, shortness of breath is caused by age, weight, or lack of exercise. However, people who have difficulty completing everyday activities due to lack of breath may be experiencing a symptom of lung cancer, especially if the symptoms have arisen in the last 12 months.
Lung cancer creates obstructions in the airway, which causes high-pitched wheezing when a person breathes.
Cancer-related obstructions also make patients more susceptible to bronchitis and pneumonia. Anyone who has been repeatedly diagnosed with these conditions should consult their doctor.
Coughing Up Blood
Coughing up blood is a sign of serious illness. When patients cough up blood, it’s normally in small amounts, mixed in with phlegm. Anyone whose sputum is red-flecked or rust-colored should consult a doctor as soon as possible.
Sudden Weight Loss
Lung cancer lowers a person’s appetite and alters their metabolism, which often leads to weight loss. Over 70 percent of cancer patients experience weight loss before they’re diagnosed. Anyone who has lost 5 percent of their body weight or more than 10 pounds over the past 12 months, without a discernable cause, should consult a doctor.
Though the lungs don’t possess any pain fibers, the outer lining of the lungs (pleura) do. If the cancer spreads to them, it can cause persistent pain. Chest pain is an early symptom and half of all lung cancer patients suffer from chest pains when they’re diagnosed.
Shoulder Pain, Back Pain, & Arm Pain
As lung cancer grows, it can put pressure on the nerve roots around the lungs, which can trigger pain in the shoulders, back, and arms. This type of pain is normally an early symptom, but it can also be a sign the cancer has spread to the bones.
Uncommon symptoms of lung cancer include hoarseness, headaches, dizziness, fatigue, and jaundice. It can also cause blood clots, leading to deep vein thrombosis and pulmonary embolisms. Patients may also experience swelling in their face and neck, as well as lumps around their neck and collarbone.
Lung Cancer Screening
The only reliable method for lung cancer screening is low-dose computed tomography (CT). CT scans create detailed images of internal organs through a series of x-ray pictures taken from varying angles around the body. Computers compile these pictures into a series of slices that doctors examine in detail. CT scans reveal the size of the tumor, its shape, and its location. High-risk patients who receive annual CT scans for three years are 20 percent less likely to die from lung cancer. Doctors have also experimented with traditional x-rays and sputum cytology (examining samples of mucus under a microscope), but neither improves long-term survival rates.
CT scans expose patients to small doses of radiation and therefore carry a small element of risk. An annual CT scan raises the risk of developing lung cancer by 5.5 percent, which is why they’re reserved for high-risk patients. According to the U.S. Preventive Services Task Force, these are patients 55-80 years old, who are heavy smokers (one pack per day for 30 years or two packs per day for 15 years), and who either still smoke or have quit smoking within the past 15 years.
Lung cancer forms nodules that can be detected by a CT scan. Doctors define nodules as spots that are three centimeters or less. Spots over three centimeters are lung masses. Nodules appear on one out of every 100 CT scans and most (60 percent) are benign, caused by old infections, scars, or inflamed tissue. Unfortunately, the likelihood that a nodule is cancerous increases as patients get older. While less than one percent of the nodules on patients under 35 are cancerous, half of the nodules on patients over 50 are cancerous.
If doctors find a nodule on a CT scan, they will evaluate it using nine criteria to determine the likelihood it’s cancerous. The first criteria is age. The others are:
Larger nodules are more likely to be cancerous than small ones.
Nodules on current or former smokers are more likely to be cancerous.
People in certain occupations (chemists, painters, printers, masons, miners, metalworkers, asbestos workers, bartenders, and truck drivers, as well as rubber, aluminum, glass, and coke manufacturers) are more likely to develop lung cancer.
If a patient has been diagnosed with cancer before, it’s more likely their nodule is cancerous.
Irregular nodules with spikes or points (speculated) are more likely to be cancerous than nodules that are smooth and round.
Cancerous nodules grow quickly, sometimes doubling in size in as little as four months. Benign nodules normally don’t get any bigger.
Calcified nodules are less likely to be cancerous.
Cavitary nodules have dark spots in their center and are less likely to be cancerous.
Doctors also evaluate nodules by comparing current scans to older scans. Nodules present on earlier scans without changing are rarely a cause for concern. However, ifthe nodule is new or larger than before, the doctor will ask the patient to return for additional scans or a biopsy.
Lung Cancer Prevention
Smoking is the leading cause of lung cancer. Between 80 and 90 percent of all lung cancer is cause by smoking. Male smokers are 23 times more likely to develop lung cancer and female smokers are 13 times more likely. Nonsmokers regularly exposed to secondhand smoke are 20 to 30 percent more likely to develop lung cancer. Smokers worried about developing lung cancer should stop immediately to lower their risk. Nonsmokers should avoid secondhand smoke as much as they can.
Exposure to hazardous substances is the second biggest cause of lung cancer in America, particularly radon. Radon is a naturally occurring gas caused by the breakdown of uranium in igneous rock and soil. According to the EPA, almost a third of American homes have dangerously high radon levels and, according to the Surgeon General, 20,000 Americans die every year from lung cancer caused by radon. Radon test kits are available at hardware stores and online. Reduce radon levels by sealing cracks in the foundation and installing a radon vent to safely discharge the gas outside.
The third biggest cause of lung cancer is lifestyle. According to the World Cancer Research Fund, approximately 20 percent of cancers, including lung cancer, are related to weight, physical activity, alcohol consumption, and poor nutrition. A 2003 study published in the American Journal of Epidemiology found that regular exercise and a healthy diet lowered the risk of lung cancer in both men and women. A healthy diet is high in fruit, vegetables, and complex carbohydrates, and low in alcohol and sugar. Regular exercise doesn’t have to involve trips to the gym. Walking, gardening, and other types low-level physical activity are also effective if done regularly. Doctors recommend setting aside 150 minutes every week for exercise and other active hobbies.
Lung Cancer Stages
Lung cancer stages describe how far the cancer has progressed and helps doctors determine the appropriate course of treatment. Doctors determine the cancer’s stage based on the patient’s CT scan. If the scan shows extensive growth, a blood test may also be necessary to see whether the cancer has metastasized.
The cancer is only located in the top layer cells lining the bronchioles. Cells in the deeper tissues are still normal and healthy and the lymph nodes are cancer free.
A small tumor has appeared on the lungs, but it is less than 5 centimeters wide. The cancer has not reached the membranes around the lungs and has not spread to the lymph nodes. The main bronchi are not affected.
The tumor is 5-7 centimeters wide. It will have spread either to the nearby lymph nodes or into the deep tissue of the lungs.
The tumor has begun to affect lymph nodes and structures beyond the lungs. It may have grown into the chest wall, the diaphragm, the membrane sac around the heart, the trachea, the esophagus, the aorta, or the backbone. Cancer cells may have also spread to the lymph nodes in the main airway or to the nodes in the center of the chest.
The cancer has metastasized and spread to distant organs, including the second lung, the liver, the bones, and the brain.
Normally, once lung cancer has reached stage III or IV, it cannot be removed surgically. However, it can still be treated with alternative methods, such as radiation or chemotherapy.
Lung Cancer Treatments
Doctors treat lung cancer using surgery, chemotherapy, and radiation. The type of treatment they recommend varies depending on the type of cancer, how far it’s progressed, the patient’s age, and their overall health. Generally, early stage cancers respond better to treatment that late stage cancers.
If the cancer has not spread outside the lungs, it’s possible to remove it using surgery. The most effective lung cancer surgery is a lobectomy. Lungs have five lobes, three in the right and two in the left. During a lobectomy, surgeons remove the entire infected lobe. If the lobe cannot be removed, surgeons have three options: a wedge resection, a segmentectomy, or a pneumonectomy. A wedge resection removes the tumor and a wedge-shaped section of the healthy tissue around it. A segmentectomy removes the infected segment from the lobe (each lobe is divided into 3-5 segments). A pneumonectomy removes the entire lung. This is a surgery of last resort. It’s only performed if the cancer has spread throughout the entire lung or if it’s located near the center of the chest.
Chemotherapy is one of the most effective treatments for lung cancer. It not only improves the patient’s lifespan, but their quality of life as well. Though sometimes chemotherapy is used as the primary treatment for lung cancer, more often it’s used along with surgery and radiation. It’s used use it to shrink tumors before surgery or radiation therapy and to eliminate remaining cancer cells afterwards. Chemotherapy can also be used as a palliative treatment, to ease symptoms caused by large tumors.
Doctors use radiation therapy to kill cancer cells, relieve cancer symptoms, and shrink tumors before surgery. The most common type of radiotherapy is external beam radiotherapy, which projects a beam of high-energy particles is projected onto the tumor from an outside source. To minimize harm to the surrounding tissue, doctors can shape the beam to match the size of the tumor, a technique called intensity modulated radiation therapy. If a patient is not healthy enough to withstand invasive surgery, doctors can perform stereotactic radiosurgery instead. Over the course of a day, the patient receives several intense radiotherapy sessions to kill their cancer cells. If the patient is not healthy enough to withstand external beam radiation, doctors can place a small amount of sealed radioactive material directly onto or near the tumor site instead.
Patients being treated for lung cancer should consider volunteering for a clinical trial. Clinical trials are where new cancer treatments are developed and tested. These trials not only give patients access to the latest science, they also help advance medical knowledge and help future patients fight their disease.