Metastatic Cancer to the Lungs

Cancers Which May Spread to the Lungs

diagram of cancer cells dividing
Understanding lung metastases from other cancers. istockphoto.com

Metastatic cancer to the lungs refers to the spread of a cancer from another region of the body to the lungs. This is also referred to as secondary cancer in the lungs. 

Metastatic cancer to the lungs also referred to as lung metastases, can be very confusing. The place where cancer begins is called the primary cancer. For example, if breast cancer spreads to the lungs, it would be called breast cancer with metastasis (spread) to the lungs.

In this case, breast cancer would be considered the “primary” cancer. If you look at the cancer cells in the lungs, in this case, they would appear to be cancerous breast cancer cells, not lung cells.

For information on metastatic lung cancer (cancer that begins in the lungs and spreads to another region of the body), see Stage 4 (Metastatic) Lung Cancer and Where Does Lung Cancer Spread?

Cancers That May Spread to the Lungs

Almost any cancer can spread to the lungs. The most common types of cancer that metastasize to the lungs include:

  • Bladder cancer
  • Breast cancer: Breast cancer commonly spreads to the lungs, and of those who have metastatic breast cancer, x percent will have lung metastases.
  • Colon cancer
  • Kidney cancer
  • Prostate cancer
  • Neuroblastoma (usually found in infants and children)
  • Sarcoma
  • Wilm's tumor

Occasionally, physicians are unable to determine where the primary site of a cancer. In this case, they refer to the cancer as a cancer of unknown origin with metastasis to the lungs.

 

Symptoms of Cancer That Has Spread to the Lungs

Sometimes lung metastases are present but do not cause any symptoms. When this is the case, the metastases may be found on a radiological exam done to look for the presence of the spread of cancer. For example, you may have a PET scan after having breast cancer and lung metastases may be found even if you aren't having any symptoms.

Symptoms of cancer metastatic to the lungs, when present, are often similar to symptoms of primary lung cancer and can include:

With lung metastases, people often have symptoms related to the primary cancer in addition to lung symptoms. For example, you may have abdominal symptoms related to a primary colon cancer in addition to lung symptoms related to lung metastases.

Since metastatic cancer implies that the primary cancer has spread through the body, general symptoms such as fatigue, unexplained weight loss, and decreased appetite are common as well.

Diagnosis of Lung Metastases

If your doctor suspects that you have lung metastases, there are several tests she may consider. These include:

  • A chest x-ray
  • CT scan of the chest
  • PET scan 
  • Lung biopsy (either a needle biopsy or open lung biopsy)
  • Analysis of pleural fluid if a pleural effusion is present
  • Bronchoscopy

Treatment of Lung Metastases

Treatment for cancer metastatic to the lungs is usually determined by the primary cancer, or origin of the cancer. These treatments may include hormonal therapy, targeted therapies, chemotherapy, immunotherapy or a combination of treatments.

Chemotherapy is often the treatment of choice, and is given as palliative therapy; therapy to prolong survival and decrease symptoms but not intended to cure the cancer. In rare instances, particularly with testicular cancer metastatic to the lungs, chemotherapy may be curative.

Occasionally, surgical treatment of lung metastases may be considered. In order for this to be effective, your doctor will want to make sure that your primary tumor is completely removed, that there are only a few (oligometastases) metastases in the lung, and that surgery will be able to completely remove these metastases.

In addition to surgery, stereotactic body radiotherapy (SBRT), also referred to by terms such as "cyberknife," is sometimes used to treat metastases to the lungs from cancer in other organs. Proton beam therapy may also be considered.

Prognosis of Cancer with Lung Metastases

Unfortunately, cancer that has spread to the lungs—by definition stage 4 cancer—is usually not curable, and life expectancy is usually fairly short. That said, metastatic cancer is often treatable, and your doctor will talk with you about treatments that may lengthen your life as well as give you the best quality of life possible.

It's likely that the prognosis for cancer with lung metastases will improve in the near future. Already some stage 4 cancers have responded to treatments such as immunotherapy in ways that were unheard of only a few years ago.

Bottom Line on Cancer Spread to the Lungs (Lung Metastases)

When cancers that originate in another area of the body, such as the breast or bladder, spread to the lungs, people may have symptoms similar to those with lung cancer. Lung metastases, however, are usually treated as part of the treatment for the primary cancer. If a breast cancer spreads to the lungs it will be cancerous breast cells in the lungs, not lung cells.

Metastatic cancers are not usually curable (there are uncommon exceptions) but they are treatable, and treatment may both extend life and control symptoms.

Sources:

National Cancer Institute. Metastatic Cancer. Updated 02/06/17. https://www.cancer.gov/types/metastatic-cancer

U.S. National Library of Medicine. Medline Plus. Lung Metastases. Updated 08/16/17. https://medlineplus.gov/ency/article/000097.htm

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