Table of ContentsView AllTable of ContentsPrimary Lung CancerSecondary Lung CancerSecond Primary Lung CancerTwo Primary Lung CancersUnknown Primary
Table of ContentsView All
View All
Table of Contents
Primary Lung Cancer
Secondary Lung Cancer
Second Primary Lung Cancer
Two Primary Lung Cancers
Unknown Primary
Lung canceris described based on where the disease originated. Cancer that starts in the lungs and is unrelated to any previous cancer is called primary lung cancer. Secondary lung cancer, on the other hand, is cancer that spreads to the lungs from another part of the body.
A second primary lung cancer is a new lung cancer that develops in the lungs unrelated to the original cancer. There is also a type of lung cancer referred to as lung cancer of unknown origin, when the origin can’t be determined.
Primary lung cancer is cancer that begins in the lungs and is most often simply referred to as “lung cancer.“Your healthcare provider probably won’t use the word “primary” to describe it.
Non-small cell lung cancer (NSCLC),small cell lung cancer (SCLC),carcinoid tumor, and other rarer types of lung tumors are all primary lung cancers.
Common causes for primary lung cancer include:
Symptoms vary, depending on the type and stage of lung cancer. General cancer-related symptoms including fatigue,unexplained weight loss, and decreased appetite are common.
Symptoms of primary lung cancer can also include:
Complications can includehypoxemia(low blood oxygen level) orpleural effusion(fluid in the space around lungs), which can manifest with shortness of breath.
When Primary Lung Cancer Spreads
Cells from a primary lung cancer tumor can sometimes break off and travel through the bloodstream or the lymphatic system. These cells can settle in other organs or regions of the body and begin to grow new tumors. This process is calledmetastasis.
The tumors that grow in these new areas are composed of lung cancer cells, so they’re still referred to as lung cancer. Specifically, they are referred to as “primary lung cancer metastatic to [area where they have spread to].”
For example, if lung cancer has spread to the brain, it would be referred to as “primary lung cancer metastatic to the brain,” not “brain cancer.” It may also be referred to as “lung cancer metastatic to the brain” or “metastatic brain cancer from the lung.” Lung cancer in the brain is considered secondary brain cancer.
The most common sites for lung cancer metastases are:
Lung cancer may be diagnosed after it has already spread to other areas of the body. In 40% of people newly diagnosed with lung cancer, tumors have already metastasized elsewhere.
Treatment for Metastasized Lung Cancer
Treatment for cancers that originated from lung cancer tumors depends upon where the cells have metastasized to.
In the same way that a brain tumor that originates from a primary lung tumor is deemed secondary brain cancer, a tumor in the lungs that has metastasized from cancer elsewhere in the body is called secondary lung cancer.
Cancer thatoriginates in the breast and spreads to the lungs, for instance, falls into this category. A healthcare provider will likely use designations such asprimary breast cancer metastatic to the lung, breast cancer metastatic to the lung, or metastatic lung cancer from the breast.
Here, cancerous breast cells, rather than cancerous lung cells, are what form the lung tumor. The same follows for secondary lung cancer due to metastatic liver cancer or pancreatic cancer.
Cancer first appears in one lung. Technically speaking, if cancer spreads to the other lung, the new tumor is considered secondary lung cancer. It will be referred to as a lung metastasis from primary lung cancer. On your lab report, it might say something like “primary lung cancer metastatic to another region in the lungs.”
Symptoms of secondary lung cancer are the same as the symptoms of primary lung cancer.
Treatment of Secondary Lung Cancer
Secondary lung cancer may require different treatment approaches than primary lung cancer. Chemotherapy is often the first course of treatment for cancer metastatic to the lung.
Other treatment options may be used, depending on the primary cancer. Options may includetargeted therapies,immunotherapy, or a combination of treatments.
Palliative therapy may be used to reduce pain or help manage other symptoms. It can extend survival and improve your quality of life, but it is not offered as a cure.
In an effort to make treatment most effective, researchers have been studying the use of inhaled chemotherapy, which offers some hope of delivering the cancer-killing medication directly to the lungs.
After being diagnosed with lung cancer once, another cancer can later develop in one of your lungs. This type of malignancy is known as “second primary lung cancer” because it appears after an earlier diagnosis and represents a new origin point.
Approximately 1 to 2% of lung cancer patients develop second primary lung cancer each year.A second primary lung cancer may be found at any time after your first diagnosis.
Risks for Second Primary Lung Cancer
The greatest risk factor for a second primary lung cancer is continued smoking.
Some cancer treatments can also increase your chances of second primary cancers. Chemotherapy and radiation therapy each raise the risk of developing another cancer in a lung or anywhere in your body.
Other factors that impact your likelihood of second primary cancer includeinherited gene mutationsand exposure to carcinogens such as tobacco smoke.
Treatment for Second Primary Lung Cancer
Treatment options for a new lung tumor of a different origin are the same as the general treatments available for a first primary lung cancer. The recommended course depends on the type of cancer andwhat stage it has reached.
Even if all tumors have been surgically removed and your primary cancer is inremission, cancer can recur years later. If the recurrent cancer is the same type of cancer (lung cancer cells with the same mutation), the new appearance will be considered a metastasis from the primary lung cancer, not a new primary or second primary cancer.
Developing two separate, unrelated lung cancers simultaneously may seem very strange, but it’s not uncommon. Actually, it is understandable when you consider that therisk factorsfor both primary tumors are the same.
For example, people who carry a genetic risk for breast cancer sometimes develop two separate and unrelated breast cancers due to agene mutationthey carry. Likewise, people who have agenetic risk for lung canceror are exposed to substances that cause the disease, such as tobacco, may also develop two unrelated lung cancers.
In this scenario, both tumors would be considered primary lung cancers. It can be difficult at first to know whether two cancers like this are related. Healthcare providers are increasingly making use of advanced testing such asmolecular profiling of lung cancersto make these types of determinations.
Cancer of Unknown Primary Cause
Healthcare providers can’t always determine the origin of a lung cancer tumor. Tests may not be able to confirm if the cancer started in the lung or another part of the body.In this instance, the tumor is known as “cancer of unknown primary” or “metastatic cancer to the lungs of unknown origin.”
The cells in these tumors are often very undifferentiated, meaning it’s challenging to tell what type of cell they were before they became malignant—and, therefore it’s hard to identify where they traveled from.
Summary
Secondary lung cancer, however, refers to cancer that originated elsewhere in the body, like in the breast or liver, and spread to the lungs. Treatment for secondary lung cancer often focuses on the primary cancer. There’s also the possibility of developing a second, unrelated primary lung cancer due to genetic factors, previous treatments, or continued smoking.
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12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Cancer Institute.Primary Cancer.American Cancer Society.What Causes Lung Cancer?.American Cancer Society.Signs and symptoms of lung cancer.American Cancer Society.Signs and Symptoms of Lung Cancer.Riihimäki M, Hemminki A, Fallah M, et al.Metastatic sites and survival in lung cancer.Lung Cancer. 2014;86(1):78-84.doi:10.1016/j.lungcan.2014.07.020Zappa C, Mousa SA.Non-small cell lung cancer: current treatment and future advances.Transl Lung Cancer Res.2016;5(3):288-300. doi:10.21037/tlcr.2016.06.07Rosière R, Berghmans T, De vuyst P, Amighi K, Wauthoz N.The position of inhaled chemotherapy in the care of patients with lung tumors: clinical feasibility and indications according to recent pharmaceutical progresses.Cancers(Basel). 2019;11(3). doi:10.3390/cancers11030329Reinmuth N, Stumpf A, Stumpf P, et al.Characteristics and outcome of patients with second primary lung cancer.Eur Respir J. 2013;42(6):1668-76. doi: 10.1183/09031936.00022512Ha D, Choi H, Chevalier C, Zell K, Wang XF, Mazzone PJ.Survival in patients with metachronous second primary lung cancer.Ann Am Thorac Soc. 2015;12(1):79-84.doi:10.1513/AnnalsATS.201406-261OCNational Cancer Institute.Second primary cancer.El-telbany A, Ma PC.Cancer genes in lung cancer: racial disparities: are there any?.Genes Cancer. 2012;3(7-8):467-80. doi:10.1177%2F1947601912465177American Cancer Society.What Is a Cancer of Unknown Primary?Additional ReadingNational Cancer Institute.Carcinoma of Unknown Primary Treatment - Health Professional Version.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
National Cancer Institute.Primary Cancer.American Cancer Society.What Causes Lung Cancer?.American Cancer Society.Signs and symptoms of lung cancer.American Cancer Society.Signs and Symptoms of Lung Cancer.Riihimäki M, Hemminki A, Fallah M, et al.Metastatic sites and survival in lung cancer.Lung Cancer. 2014;86(1):78-84.doi:10.1016/j.lungcan.2014.07.020Zappa C, Mousa SA.Non-small cell lung cancer: current treatment and future advances.Transl Lung Cancer Res.2016;5(3):288-300. doi:10.21037/tlcr.2016.06.07Rosière R, Berghmans T, De vuyst P, Amighi K, Wauthoz N.The position of inhaled chemotherapy in the care of patients with lung tumors: clinical feasibility and indications according to recent pharmaceutical progresses.Cancers(Basel). 2019;11(3). doi:10.3390/cancers11030329Reinmuth N, Stumpf A, Stumpf P, et al.Characteristics and outcome of patients with second primary lung cancer.Eur Respir J. 2013;42(6):1668-76. doi: 10.1183/09031936.00022512Ha D, Choi H, Chevalier C, Zell K, Wang XF, Mazzone PJ.Survival in patients with metachronous second primary lung cancer.Ann Am Thorac Soc. 2015;12(1):79-84.doi:10.1513/AnnalsATS.201406-261OCNational Cancer Institute.Second primary cancer.El-telbany A, Ma PC.Cancer genes in lung cancer: racial disparities: are there any?.Genes Cancer. 2012;3(7-8):467-80. doi:10.1177%2F1947601912465177American Cancer Society.What Is a Cancer of Unknown Primary?
National Cancer Institute.Primary Cancer.
American Cancer Society.What Causes Lung Cancer?.
American Cancer Society.Signs and symptoms of lung cancer.
American Cancer Society.Signs and Symptoms of Lung Cancer.
Riihimäki M, Hemminki A, Fallah M, et al.Metastatic sites and survival in lung cancer.Lung Cancer. 2014;86(1):78-84.doi:10.1016/j.lungcan.2014.07.020
Zappa C, Mousa SA.Non-small cell lung cancer: current treatment and future advances.Transl Lung Cancer Res.2016;5(3):288-300. doi:10.21037/tlcr.2016.06.07
Rosière R, Berghmans T, De vuyst P, Amighi K, Wauthoz N.The position of inhaled chemotherapy in the care of patients with lung tumors: clinical feasibility and indications according to recent pharmaceutical progresses.Cancers(Basel). 2019;11(3). doi:10.3390/cancers11030329
Reinmuth N, Stumpf A, Stumpf P, et al.Characteristics and outcome of patients with second primary lung cancer.Eur Respir J. 2013;42(6):1668-76. doi: 10.1183/09031936.00022512
Ha D, Choi H, Chevalier C, Zell K, Wang XF, Mazzone PJ.Survival in patients with metachronous second primary lung cancer.Ann Am Thorac Soc. 2015;12(1):79-84.doi:10.1513/AnnalsATS.201406-261OC
National Cancer Institute.Second primary cancer.
El-telbany A, Ma PC.Cancer genes in lung cancer: racial disparities: are there any?.Genes Cancer. 2012;3(7-8):467-80. doi:10.1177%2F1947601912465177
American Cancer Society.What Is a Cancer of Unknown Primary?
National Cancer Institute.Carcinoma of Unknown Primary Treatment - Health Professional Version.
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