When cancer metastasizes (spreads), it often targets specific organs. Many types of cancer spread from their original location to the lungs. This is known as secondary lung cancer, and it’s usually associated with a poor prognosis (outlook).

In this article, we’ll discuss what secondary lung cancer is and which cancers it typically develops from. We’ll also cover how a secondary cancer can affect your prognosis. Your doctor or oncologist (cancer specialist) can discuss your individual treatment plan.

What Is Secondary Lung Cancer?

“Secondary lung cancer” refers to cancer that has spread from one location to the lungs. “Primary tumor” refers to the tumor where cancer started growing. Cancer cells can break off of the tumor and enter the bloodstream. These cells can also travel through the lymphatic system — which carries immune cells and filters blood.

Many cancer types spread to the lungs because blood is always flowing through them. Once cancer cells reach the bloodstream, they can travel and start forming new tumors in the lungs. Remember, the cancer cells will still be the same as those from the original organ affected by cancer — that is, if breast cancer cells spread to the lungs, they’ll still look like breast cells under a microscope.

It’s also possible to develop lung cancer as a second primary cancer — which means having two different types of cancer, either simultaneously or at different points in life. This is different from a secondary cancer because the cancer develops in lung cells. In order for a cancer to be considered secondary, it needs to come from another organ. The table below summarizes information about primary and secondary lung cancers.

Where Are Secondary Lung Tumors Located?

Lung metastases can form one or more tumors anywhere in one or both lungs. The lungs contain lobes (areas of tissue). The right lung has three lobes, and the left lung has two. According to the Canadian Cancer Society, secondary lung cancers are more likely to form along the outer edges of the lung in the lower lobes. The cancer can also spread inside the chest cavity, affecting the:

• Mediastinum — The middle of the chest cavity that contains the heart and major blood vessels
• Pleura — Thin layers of tissue that cover and protect the lungs

Certain Cancer Types Spread to the Lungs

Any type of cancer is capable of spreading anywhere in the body. However, some cancers prefer to spread to certain places. The most common causes of secondary lung cancers are:

• Breast cancer
• Colorectal cancer or bowel cancer
• Testicular cancer
• Melanoma skin cancer
• Soft tissue and bone sarcomas
• Bladder cancer
• Renal (kidney) cancer
• Esophageal (gullet) cancer

Risk Factors Associated With Secondary Lung Cancer

Certain groups of people are more likely to develop secondary lung cancer than others. One study looked at more than 100,000 people with lung metastases. The authors found that people with cancer that spread to the lungs were more likely to be:

• Older
• Male
• Non-white
• Diagnosed with larger tumors that have spread to the lymph nodes

Secondary lung cancers can also develop from radiation therapy to the chest, though this is a relatively rare occurrence.

Symptoms of Secondary Lung Cancer

When cancer spreads from one part of the body to the lungs, it can cause noticeable symptoms. They include:

• Chest pain or discomfort that doesn’t seem to go away
• Coughing, which may include coughing up blood or sputum (mucus or phlegm)
• Shortness of breath, which may be due to pleural effusion (fluid buildup around the lungs)
• Weight loss
• Frequent lung infections

Symptoms of secondary lung metastases are usually the same as those of primary lung cancers. They can also be mistaken for other lung conditions, like bacterial infections. Your doctor may suspect you have secondary lung cancer if your symptoms don’t improve after you’ve tried antibiotics. You might also be at risk of secondary cancer if you were previously diagnosed with another type of cancer.

Be sure to let your doctor or oncologist know if you’ve experienced any new or worsening lung symptoms. They can order additional tests to make a diagnosis.

Prognosis With Secondary Lung Cancer

Unfortunately, it’s unlikely for cases of secondary lung cancer to be cured. Your oncologist will work to find the best treatment to help extend your life expectancy. Your outlook with secondary lung cancer depends on several factors, including the type of your primary cancer. Mount Sinai notes that some people can live five or more years with cancer that has spread to the lungs.

Treatments for Secondary Lung Cancer

Oncologists treat secondary lung cancers based on the primary cancer. Usually, treatments given for the primary cancer will simultaneously treat lung metastases. This is because some cancer types respond better to certain treatments. Your treatment plan can also depend on what previous treatments you received for your primary cancer. It’s important to work closely with your oncologist to find what will work best for you.

Surgery for Secondary Lung Cancer

Your oncologist may recommend surgery as part of your secondary lung cancer treatment plan. You may be a candidate for surgery if:

• Your cancer hasn’t spread to any other parts of the body, except the lungs.
• The tumor only affects one part of your lung.
• Your cancer is under control and isn’t actively spreading.
• The tumor isn’t growing on important nerves or blood vessels.

Chemotherapy for Secondary Lung Cancer

Chemotherapy uses chemicals that kill rapidly dividing cancer cells in the body. Certain chemotherapy drugs work better to treat some cancers compared to others. Your chemotherapy regimen will likely depend on previous treatments you’ve had and how long they lasted.

Hormonal Therapy for Secondary Lung Cancer

Some cancers — like prostate or breast cancer — need hormones to grow and spread. Secondary lung cancers that spread from these cancers also depend on hormones, since they come from prostate or breast cells. Oncologists can prescribe hormone therapy (also called endocrine therapy) to block these cells from growing and dividing. Your treatment plan is dependent on other therapies you’ve previously received.

Radiation Therapy

Your oncologist may recommend radiation therapy to relieve pain and discomfort from secondary lung cancer. The concentrated X-ray beams help shrink tumors to treat coughing and breathlessness. Your doctor can also place small bits of radioactive material next to a tumor to shrink it.

Immunotherapy

Immunotherapy uses lab-engineered proteins to activate the immune system against cancer. You may receive an immunotherapy drug, depending on your primary cancer. Some cancer types respond better to these medications than others. You may also receive a combination of immunotherapy with radiation therapy or chemotherapy.

Talk With Others Who Understand

MyLungCancerTeam is the social network for people with lung cancer and their loved ones. On MyLungCancerTeam, more than 13,000 members come together to ask questions, give advice, and share their stories with others who understand life with lung cancer.

Have you been diagnosed with secondary lung cancer? What type of cancer did you originally have? How has your oncologist decided to treat it? Share your experience in the comments below, or start a conversation by posting on your Activities page.