Tracking Lung Cancer's Path

It's common for lung cancer to metastasize, or spread. In fact, 57 percent of lung cancer patients are diagnosed when the cancer has already metastasized, according to an editorial in the Annals of Cancer Epidemiology .

Lung cancer also has a preferred path, traveling most often to the bones, brain, adrenal glands, and liver.

Why Does Lung Cancer Spread So Easily?

Lung cancer may metastasize readily because the lungs are a cellular traffic hub of the body. "The job of the airway is to deliver oxygen to all of your cells, so it's easy for cancer cells to get from the airway lining to the blood and spread to other organs," says Paul Bunn, MD, a professor of medical oncology at the University of Colorado School of Medicine in Aurora.

Why Do Lung Cancer Cells Spread to Certain Organs?

"Some organs produce a cellular signal that draws a particular cancer into it," says Douglas Arenberg, MD , a professor of pulmonary diseases and critical care medicine at the University of Michigan Medical School in Ann Arbor. That's where lung metastases are usually found. Scientists sometimes refer to it as the seed-and-soil hypothesis, the tumor being the seed and the soil being the organ receptive to that seed.

Cancer is always named after the place in the body where it started, though. That means if lung cancer spreads to the brain, it's called metastatic lung cancer , not brain cancer.

Breaking Down the Common Areas Lung Cancer Spreads

While lung cancer can spread to many areas of the body, certain places are more common.

Bones At the time of non-small cell lung cancer (NSCLC) diagnosis, the cancer has already spread to the bone in 20 to 30 percent of people, and 35 to 60 percent will develop bone metastasis in the course of the lung disease, according to a review.

Lung cancer that spreads to the bones typically affects the ribs, pelvis, spine, and long bones in the body, but it can spread to any bone. The cancer's spread may be seen on imaging, but it often isn't diagnosed until it causes pain or other problems.

Tests such as a bone scan, CT scan, MRI, PET scan, or X-ray can detect cancer that's moved to the bones.

Brain Studies show 10 to 50 percent of people with lung cancer will develop brain metastases, depending on factors such as the type of tumor mutation.

Symptoms of brain metastases may include difficulty talking, headaches, loss of balance, memory problems, seizures, and vision changes.

Doctors can spot lung cancer that's spread to the brain by performing a CT scan or an MRI .

Adrenal Glands The adrenal glands (small glands that sit on top of the kidneys) are a common site for lung cancer metastasis.

Usually, cancer that spreads to the adrenal glands doesn't cause symptoms. But, in rare cases, it may trigger back or abdominal pain .

Doctors can perform various scans to see if the cancer has traveled to the adrenal glands.

Liver In most cases, lung cancer that has metastasized to the liver cannot be cured. One study notes that despite recent advances in treatment for lung cancer, the odds of survival are slim for people with NSCLC that has spread to the liver.

Lung cancer that moves to the liver may not cause symptoms. When it does, symptoms may include fever, jaundice (yellowing of the skin or whites of the eyes), loss of appetite, nausea, pain in the upper right side of the abdomen, sweats, and weight loss.

Doctors can perform tests, such as an abdominal ultrasound , CT scan, MRI, or PET scan, to look for cancer that's spread to the liver.

Other Areas Occasionally, lung cancer can spread to other areas of the body, including the eyes, kidneys, pancreas , skin, small and large intestines, and stomach.

Does Size Matter?

There's a misconception that cancer must reach a certain size before it's capable of spreading, but there's no size threshold that allows a cancer to metastasize, says Dr. Arenberg. Some cancers metastasize before they're even detectable.

That said, larger tumors do tend to be more likely to find their way elsewhere. "One way to look at a tumor is that every day, it's sort of playing the lottery," Arenberg says. "The more cells there are, the more likely it is that a few will win the lottery and gain the ability to invade the bloodstream or lymph system," he explains. That's why early detection is often key to better odds of survival.

Can Metastasis Be Detected Before Symptoms Appear?

A number of tests, including blood tests , bone scans, CT scans , and MRIs, can be performed to look for metastases. Which tests are done will depend on your symptoms. The generally accepted course, says Arenberg, is to mention any symptoms to your doctor, and then the metastases can be treated to control those symptoms and improve your quality of life.

What Should You Look For?

Tell your doctor if you have any symptoms that are out of the ordinary, especially those that could indicate metastasis, such as:

• Any kind of new pain
• Neurological symptoms, such as a new headache or weakness or changes in your ability to walk or grip things
• Unintentional weight loss or loss of appetite
• Fatigue or weakness
• Jaundice

More in Lung Cancer

5 Things Not to Say to Someone With Lung Cancer (and 4 Things You Should Say)

Answers to Your Most Pressing Questions About Lung Cancer and Lymph Nodes

Navigating Non-Small-Cell Lung Cancer

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Sources

1. Zhang J et al. Lung Cancer Statistics in the United States: A Reflection on the Impact of Cancer Control. Annals of Cancer Epidemiology . February 10, 2022.
2. Megyesfalvi Z et al. The Landscape of Small Cell Lung Cancer Metastases: Organ Specificity and Timing. Thoracic Cancer . March 2021.
3. Tamura T et al. Specific Organ Metastases and Survival in Metastatic Non-Small-Cell Lung Cancer. Molecular and Clinical Oncology . January 2015.
4. Akhtar M et al. Paget's "Seed and Soil" Theory of Cancer Metastasis: An Idea Whose Time Has Come. Advances in Anatomic Pathology . January 2019.
5. Knapp BJ et al. Bone Metastases in Non-Small Cell Lung Cancer: A Narrative Review. Journal of Thoracic Disease . May 31, 2022.
6. Zhu Y et al. Small-Cell Lung Cancer Brain Metastasis: From Molecular Mechanisms to Diagnosis and Treatment. Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease . December 1, 2022.
7. Brain Metastasis From Lung Cancer. American Lung Association. November 17, 2022.
8. Metastatic Disease to the Adrenal Gland. Columbia University Adrenal Center.
9. Wang JF et al. Clinical Characteristics and Prognosis of Non-Small Cell Lung Cancer Patients With Liver Metastasis: A Population-Based Study. World Journal of Clinical Cases . October 26, 2022.
10. Liver Metastasis From Lung Cancer. American Lung Association. June 26, 2023.
11. What Are the Symptoms of Metastatic Lung Cancer? Moffitt Cancer Center.