Lung cancer is a type of cancer that forms in the tissues of the lungs, most often in the cells that line air passages. It occurs when these cells start to grow and multiply uncontrollably, usually as a result of exposure to toxins such as tobacco smoke, radiation and asbestos.
Molecular diagnosis
Lung cancer traditionally is categorized by the type of cell where it begins. Today, doctors can also diagnose the disease on a molecular level.
This approach usually looks for mutations in the DNA of cancer cells and/or proteins produced by the cells. There are hundreds of different molecular diagnoses, including mutations to the EGFR, ALK, KRAS and ROS1 genes.
These molecular subtypes can impact how quickly the disease grows and spreads. They also can predict how the disease will respond to specific treatments, including different types of chemotherapy, targeted therapy and immunotherapy. By diagnosing a patient’s disease on a molecular level, doctors can design treatment plans with the best chance of fighting each patient’s specific cancer.
Cellular diagnosis
The traditional diagnosis based on the type of cell where the cancer started can still help doctors understand the patient’s condition and make a treatment plan. The two main categories are:
Non-small cell lung cancer (NSCLC)
About 85% of lung cancer cases are considered NSCLC. It arises from the lungs’ epithelial cells, a type of cell that lines the surface of organs. There are several types of non-small cell lung cancer based on the type of epithelial cell where the disease begins, including adenocarcinoma, squamous cell carcinoma and large cell carcinoma.
Small cell lung cancer (SCLC)
About 15% of lung cancers are SCLC and almost always are caused by smoking tobacco. It often starts in the more central portions of the chest. It usually grows and spreads quickly to other parts of the body, including the lymph nodes. Because it is so aggressive, surgery is used less often for small cell lung cancer than non-small cell lung cancer.
Lung anatomy
When you breathe in, oxygen comes through your mouth and nose and then travels through the trachea, or windpipe. The trachea divides into two tubes called bronchi, which take the oxygen to the left and right lungs. Inside the lungs are smaller branches called bronchioles and alveoli, tiny air sacks where oxygen is transferred to the blood stream.
Each lung is divided into sections called lobes. The right lung has three lobes and the left lung has two lobes. The left lung is smaller than the right lung because the heart is also located in the left side of the chest. Each lobe can be further divided into bronchopulmonary segments.
The pleura is a thin membrane that covers the outside of each lung and lines the inside wall of the chest. The space between the lungs and the chest wall usually contains a very small amount of fluid that allows the lungs to move smoothly during breathing.
Cancer grows in lungs, may spread
When lung cancer is small and at an early stage, it usually does not cause symptoms. However, once the disease grows, it may damage surrounding tissue, interfering with the lungs’ normal function and causing symptoms such as hemoptysis (coughing up blood), shortness of breath or pain.
Lung cancer frequently spreads, or metastasizes through the lymphatic system. Lymph is a clear fluid that is drained from our tissues and contains immune cells that help fight infection. It travels through your body in lymphatic vessels. Lymph nodes are small, bean-shaped organs that link lymph vessels. They often trap cancer cells that have spread to the lymphatic system.
Cancer cells can spread to other parts of your body through the bloodstream, as well. When lung cancer spreads to other organs such as the liver or bone, it is known as stage IV lung cancer or metastatic lung cancer. Cancer that has spread to another organ is still referred to as lung cancer. Whether or not a lung cancer has spread to lymph nodes or to other organs significantly influences how the tumor is treated.
Lung metastases
Sometimes, a tumor starts in another part of the body and then spreads, or metastasizes, to the lungs. These tumors are called lung metastases, and they are not the same as lung cancer. In these cases, they are the type of cancer where they came from. For example, a colon cancer with lung metastases is called metastatic colon cancer.
Statistics
Lung cancer is the most common cause of cancer-related deaths and second most common cancer in both men and women in the United States. According to the National Cancer Institute, more than 230,000 people in the U.S. are diagnosed with the disease each year. While most cases are linked to tobacco smoking, a growing number of diagnoses are among non-smokers, especially among women. Most lung cancers are diagnosed after the disease has spread. As a result, the five-year survival rate for lung cancers is 22%, though cases that are caught before the disease has spread have a much higher survival rate.
Risk factors
A risk factor is anything that increases the chance that a person will develop a particular disease. The main risk factors for lung cancer are:
- A history of or current tobacco use
- Exposure to second-hand smoke
- Exposure to asbestos, arsenic, chromium or other chemicals
- Living in an area with air pollution
- A family history of lung cancer
- Infection with the human immunodeficiency virus (HIV)
- Radiation exposure, including radiation therapy to the breast or chest, and radon exposure. This is a minor risk factor and the benefits of radiation therapy as a cancer treatment far outweigh the risks.
In some cases, lung cancer can be passed down from one generation to the next. Genetic counseling may be right for you. Visit our family history site to learn more about genetic counseling and testing.
What's the best way to quit smoking?
Smoking is on the decline. But if you are one of the 28 million Americans still smoking, you probably know how hard it is to quit.
Close to 70% of smokers report that they want to stop smoking. Of those, 55% said they tried to quit in the previous year. Only around 7% succeeded.
There are plenty of reasons to try to reduce your nicotine addiction: Tobacco use – and smoking, in particular – accounts for about one-third of all cancers, and up to 90% of lung cancer cases. It also contributes to heart disease, stroke and lung disease.
So, what's the best way to quit smoking?
“The best way to quit smoking is with a combination of medication and counseling,” says Maher Karam-Hage, M.D., medical director of the Tobacco Research and Treatment Program at MD Anderson. “They both help. But you double your chances by using both compared with one of them.”
What products can help you quit smoking?
There are several products that can help reduce your nicotine cravings.
Prescription medication
Smoking cessation options that require a doctor’s prescription include:
Varenicline (formerly sold as Chantix) works in two ways. First, it provides a mild version of nicotine’s effects. This helps reduce withdrawal symptoms and cravings. Second, it stops your brain from feeling the pleasurable effects of nicotine when you smoke. This makes smoking less appealing. Varenicline is the most effective single medication, Karam-Hage says. But it's also the most expensive.
Bupropion (also sold as Zyban or Wellbutrin) blocks the effects of nicotine in your brain. This makes smoking feel less pleasurable, but it does not replace the effect of nicotine.
Nicotine nasal spray is a nicotine replacement therapy that is sprayed into the nostril and absorbed into the nasal lining and bloodstream. This product provides nicotine without the other harmful effects of cigarettes.
Over-the-counter options
Over-the-counter nicotine replacement therapies partially satisfy nicotine cravings by giving the body small amounts of nicotine. This can help with cravings and make it easier to stop smoking.
The over-the-counter nicotine replacement therapies available in the United States are:
Nicotine patches are 3- or 4-inch-wide patches that release a steady dose of nicotine. They are applied to the upper body and changed daily. They come in 7 mg, 14 mg and 21 mg doses.
Lozenges release nicotine as they dissolve in the mouth. They are available in mini and regular sizes and 2 mg and 4 mg doses.
Nicotine gum users follow the ‘chew and park’ method. The gum is chewed for 5 to 10 seconds then parked between the teeth and cheek for another 5 to 10 seconds. This process is then repeated in different parts of the mouth. It comes in 2mg and 4 mg doses.
Why is counseling important?
Working with a counselor can help you better understand your medication. A counselor can also give you the tools to cope with setbacks, stress and cravings by building skills in several areas. These include:
Problem solving
We all run into problems in life, like personal conflicts, that can make us feel helpless. Working with a counselor to tackle them one at a time can help you build knowledge and skills that can be used in other areas.
Coping strategies
Anything from a traffic jam to a death in the family can set off a strong urge to smoke. Learning strategies like deep breathing exercises, meditation and mindfulness can help a smoker get to the other side of a crisis without smoking.
Behavior change
Smokers who quit may miss the “hand-to-mouth” act of smoking. Counseling can help them find substitutions like using a straw, cinnamon stick or gum.
Identifying triggers
Counseling can help you identify what triggers you to smoke, like that morning cup of coffee or spending time with friends who smoke. Once you identify your triggers, you can learn to deal with them or avoid them.
Once smokers start counseling, they appreciate the tools and support it provides in their effort to quit smoking, Karam-Hage says.
“Finally, somebody understands the struggle they're going through,” he says. “Someone is acknowledging that it's not a simple thing to quit. That is very helpful.”
What option should you try first?
Not sure where to start? For many, over-the-counter nicotine replacement therapies are quicker and easier to get than medication because they don’t require prescriptions and can be purchased at most pharmacies.
However, remember that nicotine replacement therapies must be used consistently to be effective. If you find it hard to regularly use options like the patch, lozenges or gum, or if they don’t help you quit, Karam-Hage says you might consider medication.
Your doctor can prescribe medication to help you quit. They can also advise you on how to combine nicotine replacement therapies. This might look like using the patch along with either nicotine gum, lozenges or nicotine nasal spray.
Additionally, a professional counselor can help you monitor what is and isn’t working and work with a prescriber on your care team to adjust the medication you take to set you up for success.
Want to quit but don't have access to a comprehensive program that includes both counseling and medication? You have options.
You can get phone and text support through the National Institutes of Health Quitline by calling 1-800-784-8669, texting QUIT to 47848, or visiting SmokeFree.gov. If you live in Texas, you can use the Texas Tobacco Quitline by calling 1-877-YES-QUIT or visiting YESQUIT.org.
Should you quit smoking cold turkey?
Knowing the health risks and addictive properties of nicotine, you might be wondering whether you should simply quit smoking cold turkey.
Karam-Hage says it’s wonderful if a smoker can quit cold turkey, but notes it is not necessarily better than using medication and counseling. This is because while it works for some, it does not work for everyone.
Most people who attempt to quit smoking on their own fail to do so, he says. Because of this, he notes people may benefit from using both medication and counseling in future attempts to quit smoking. He says the unfortunate reality is that only about 30% of people attempting to quit get either medication or counseling, and only 5% of people get both medication and counseling.
If you’ve tried and failed to quit smoking long-term, Karam-Hage recommends a combination of counseling and medication. Enrolling in a comprehensive tobacco treatment program like MD Anderson’s Tobacco Research and Treatment Program, which is open to MD Anderson patients and caregivers, can be helpful for those seeking additional support. A 2019 study showed that 45% of people enrolled in MD Anderson’s program managed to quit smoking.
What happens to your body when you quit smoking?
Let’s start with the organ that is perhaps most associated with smoking: the lungs.
Those who quit smoking might note that they can breathe a little easier – and not just metaphorically! Karam-Hage says this is because the toxins from cigarette smoke are gone.
As for whether the lungs can regenerate after you quit smoking, the answer depends on just how damaged the lung tissue is. For lung tissue that is damaged but still alive, Karam-Hage says it is possible for it to recover. However, totally damaged cells can’t be reversed.
“Whatever cells have died are gone and no regeneration is possible,” he says, noting this is why conditions like chronic obstructive pulmonary disease (COPD) are permanent.
While smoking’s effects don’t entirely go away when you quit, Karam-Hage says there are many positive health impacts that happen when you quit smoking.
These benefits include:
- Reduced heart rate and blood pressure
- Reduced level of carbon monoxide in blood
- Improved circulation and lung function
- Improved sense of taste and smell
- Reduced risk of heart disease
- Reduced risk of stroke
- Reduced risk of mouth, throat, larynx, esophageal, bladder, cervical, lung, kidney, liver, colorectal, leukemia and pancreatic cancer
“There are many benefits, and they continue to get better as time passes,” he says.
Request an appointment at MD Anderson online or call 1-877-632-6789.
Lung anatomy & lung cancer spread
Lung anatomy and stage I lung cancer in the patient's right lung (click to enlarge)
Stage II lung cancer. Cancer cells have spread to nearby lymph nodes. (click to enlarge)
Stage III lung cancer. The cancer has spread to the left lung. (click to enlarge)
Stage IV lung cancer. The cancer has spread, or metastasized, to the liver. (click to enlarge)
Frequently asked questions
What is small cell lung cancer?
Lung cancer is traditionally categorized by the type of cell where it begins. Small cell lung cancers (SCLCs) make up about 15% of lung cancers and almost always are caused by smoking tobacco. The cancer often starts in the more central portions of the chest — in the bronchi, the two large tubes that carry air from the windpipe to the lungs. It usually grows and spreads quickly to other parts of the body, including the lymph nodes. Because this cancer is so aggressive, surgery is used less often for SCLC than for non-small cell lung cancers.
What are the stages of lung cancer?
Lung cancer stages are determined through various tests and procedures, including MRIs, CT scans, PET scans, and lymph node biopsies. The doctor will combine the results of these procedures to stage the cancer, using the TNM (tumor, node, metastasis) classification system.
Can you get lung cancer from smoking?
Yes, you can get lung cancer from smoking. MD Anderson recommends lung cancer screening if you’re age 50–80, are a current smoker (or a former smoker who quit within the past 15 years), and have a 20 pack-year smoking history (for example, one pack a day for 20 years or two packs a day for 10 years).
Is lung cancer hereditary?
Lung cancer is hereditary in some cases, and a family history of lung cancer is considered a risk factor. Some rare genetic conditions, such as Li-Fraumeni syndrome (LFS), are associated with an increased risk of developing lung cancer.
Is lung cancer curable?
Lung cancer is sometimes curable; it depends on the specific cancer a person has and how early the cancer was caught. Some lung cancers are very aggressive, while others are very responsive to targeted therapy and are curable if caught early.
How are CT scans used to diagnose lung cancer?
CT scans are used in certain instances, in combination with other tests, to help diagnose lung cancer. In the process of diagnosis, patients will typically undergo an imaging exam, usually a chest X-ray. Images alone are not enough to make a lung cancer diagnosis, but they can show areas of concern. If an image shows such an area, the doctor may order other scans, including a CT scan or a PET scan, to get additional details. If the findings of the image scans indicate cancer, the doctor will request the removal of tissue or fluid from the lung for examination. Obtaining a tissue or fluid sample is called a biopsy.
When is immunotherapy used to treat lung cancer?
Immunotherapy may be used in combination with chemotherapy as a treatment for lung cancer. However, its usefulness depends on the type of cancer being treated.
Why choose MD Anderson for your lung cancer treatment?
Choosing the right hospital may be the most important decision you can make as a lung cancer patient. At MD Anderson you’ll get treatment from one of the nation’s top-ranked cancer centers. Our expertise starts with the ability to accurately diagnose and stage even extremely rare cancers, then carries on through groundbreaking treatment and into survivorship.
As a patient at MD Anderson, you’ll see the benefits of care from a top-ranked cancer center. These include:
- Treatment from specialists who focus exclusively on lung cancer and other thoracic cancers, including radiation oncologists, medical oncologists, surgeons and pathologists.
- Molecular diagnosis of cancer cells, allowing doctors to identify which treatments have the best chance of success against your exact cancer.
- Expert surgical care designed to offer complete resection of your tumor and any involved lymph nodes.
- An enhanced surgical recovery program along with robotic and minimally invasive procedures that offer faster recovery times and less pain from surgery.
- Groundbreaking clinical trials that may not be available anywhere else. These include trials of new targeted therapies, immunotherapies and drug combinations.
MD Anderson patients also have access to all the services and support offered by one of the nation’s top-ranked comprehensive cancer centers. From counseling and support groups to integrative medicine and physical therapy, MD Anderson has all the support and wellness services needed to treat the whole person – not just the disease.
This support and care is available beyond MD Anderson’s campus in the Texas Medical Center. Through our Houston-area locations, patients throughout the region can get top-ranked care and personalized attention close to home.
They're focused on you as a person, and they're focused on fighting the disease. But they also show so much kindness and compassion.
Treatment at MD Anderson
MD Anderson lung cancer patients can get treatment at the following locations.
MD Anderson's Proton Therapy Center
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