How Lung Cancer Progresses & What to Expect

There are two main types of lung cancer: non-small cell lung cancer and small cell lung cancer. Once the type of lung cancer is identified, healthcare providers use imaging tests and biopsy results to determine how advanced the cancer is and if it has spread. This is known as staging. 

Staging helps healthcare providers identify the most effective treatment options and your likely prognosis (outcome). The two most common types of cancer are staged and treated differently. 

This article discusses the stages of cancer, how cancer progresses, where in the body it can spread, and what to expect throughout the process.

Small-Cell Lung Cancer

Small cell lung cancer (SCLC), also known as "oat cell cancer," occurs in approximately 15% of cases. SCLC occurs most often in smokers. It is highly aggressive and spreads rapidly. Approximately 84% of people diagnosed with SCLC have metastatic disease when they are diagnosed. This means cancer has spread to other parts of the body. 

SCLC is classified into two stages:

• Limited-stage: Cancer is only in one lung and may or may not have spread to the lymph nodes by the collarbone and mediastinum (area between the lungs). 
• Extensive stage: Cancer has spread to other areas of the body. It may affect both lungs and/or other organs.  

Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer.

There are five stages of NSCLC:

• Stage 0: Also called “in situ," this stage means that cancer cells are only found in the top lining of the lung or bronchus and have not spread. 
• Stage I: Tumors are small and found in only one lung. Cancer has not spread to any lymph nodes or other areas of the body. Stage I is divided into substages IA and IB, based on the size of the tumor. 
• Stage II: Tumors are located in the lung where cancer started and have not metastasized to other parts of the body. Cancer may have spread to nearby lymph nodes. Stage II is divided into substages IIA and IIB, depending on the size of the tumor(s), where it is found, and whether cancer has spread to nearby lymph nodes.  
• Stage III: Tumors are found in the lungs and lymph nodes in the chest. Stage III is divided into substages IIIA, IIIB, and IIC, depending on the size and location of the tumor and how far cancer has spread. It most commonly spreads to lymph nodes in the mediastinum and/or by the collarbone. 
• Stage IV: Cancer cells have spread (metastasized) into the lining of the lung and other areas of the body and may or may not have spread to the lymph nodes. This is the most advanced form of lung cancer.

Where Does Lung Cancer Typically Spread?

Lung cancer can spread when cancer cells break away from the original tumor and travel through the bloodstream or lymphatic system and form new tumors in other parts of the body. Lung cancer can spread to any part of the body, but the most common areas include the brain, bones, adrenal glands, liver, and lymph nodes.

If lung cancer spreads elsewhere, it is still referred to as lung cancer. For example, if it spread to the bones, it would be called lung cancer with bone metastases.

Bones

Lung cancer that has spread to the bone can cause severe pain and fractures. Approximately 30-40% of people with advanced lung cancer will develop lung cancer metastases to bones. Bones most commonly affected by metastases include the hands and feet, upper arm bone, thigh bone, pelvis, and spine. 

Brain 

Brain metastases—also called “brain mets”—occur when cancer cells in the lung break away, enter the bloodstream, and travel to the brain. This is very common in people with lung cancer. About 25% will have a brain met at the time of diagnosis, and up to 50% have a lifetime risk of developing the complication.

Liver

The liver is another common organ lung cancer cells affect. Up to 20% of people with small-cell lung cancer and 4% of patients with NSCLC will experience lung cancer metastatic to the liver. Lung cancer metastatic to the liver may cause abdominal pain and swelling, loss of appetite, and nausea. If the tumor blocks your bile ducts, you may develop jaundice.

Adrenal Glands

The adrenal glands are small, triangle-shaped glands located on the top of each kidney. They are responsible for secreting hormones, including “stress hormones” (e.g., cortisol, adrenaline). Adrenal metastases occur in up to 40% of people with lung cancer, though it is present in less than 10% of patients at the time of diagnosis.

Lymph Nodes

Lymph nodes are often the first area of the body where lung cancer cells are found if/when it spreads. Lymph nodes help filter out body waste and toxins. When lung cancer cells break away from the primary tumor location and travel through the lymphatic system, the cells are carried to lymph nodes.

If the spread of the cells is limited to lymph nodes close to the primary tumor, it is called “locally advanced." If cancer cells have spread to lymph nodes further away from the primary tumor, it is considered metastatic.

Prognosis

If you’ve been diagnosed with lung cancer, chances are you are wondering about your prognosis. A prognosis is an estimate of how lung cancer will affect you and how the type/stage you have will respond to treatment.

Your healthcare provider may use the Lung Cancer Prognostic Index (LCPI) to determine your prognosis. This tool weighs several factors—including the stage and type of lung cancer, your medical history, smoking history, sex, and age—to make an estimated prognosis.

Lung cancer is most responsive to treatment when detected and treated early. It’s important to remember that survival rates and a prognosis are just your healthcare provider’s “best guess." Nobody can tell you what will happen in your individual case, and your prognosis depends on many factors. 

What to Expect

Lung cancer progression varies from person to person. There is no standard timeline for the progression of lung cancer, but knowing what to expect before, during, and after treatment can help you prepare for what lies ahead. Your healthcare team can help you make any lifestyle changes that will support your recovery and guide you in making treatment and health-related decisions. 

Though no two people’s lung cancer journeys will be exactly alike, there are certain things you can expect:

• An emotional journey: You may feel as if you’re on an emotional roller coaster with a variety of emotions such as grief, sadness, anger, or fear. Express your feelings with trusted friends/family, write a journal, or find community and support in a lung cancer support group. 
• Relationship changes: A cancer diagnosis can impact your relationships—some may get stronger, and others may grow more distant. 
• Lifestyle changes: You may need to make certain changes to your habits to support your health, such as quitting smoking, eating a healthy diet, staying physically active, and reducing stress. 
• Side effects: You may feel symptoms of lung cancer as well as side effects from treatments (e.g., chemotherapy, radiation). Talk to your healthcare provider about how to manage treatment-related side effects. 
• Advocating for yourself: Though your healthcare team will have your best interests in mind, you know yourself best. Be your own advocate by asking questions, researching treatments, and sharing your needs with your healthcare provider, family, and friends. 

Summary 

Non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) are the two main types of lung cancer. The staging and progression of these two types are different. Once the type of lung cancer has been identified, healthcare providers will use imaging tests and biopsy results to determine how advanced the cancer is and if it has spread (staging). 

NSCLC progresses in five different stages (stages 0-5), and SCLC has two stages: limited and extensive. The stages depend on the size and location of the primary tumor, whether it has spread (metastasized), and what part(s) of the body it has spread to. Staging helps healthcare providers identify the most effective treatment options to improve your outcome.

Getting a diagnosis at an early stage before cancer has metastasized to other areas of the body can have a positive impact on your prognosis. 

A Word From Verywell

Living with lung cancer can be physically and emotionally draining, and may leave you with a lot of questions about how your cancer may progress and what the future holds. Knowing the type and stage of cancer you have can help you make an informed decision about the best treatment options for you. Advancements in lung cancer detection and treatment in recent years have led to significant improvements in lung cancer survival rates.