Types of Cancer and How They Differ
What To Know About Lung Carcinoid Tumors
A lung carcinoid tumor — or pulmonary carcinoid tumor — is a rare type of lung cancer. Carcinoids are tumors that develop from neuroendocrine cells found in different parts of the body, such as the lungs and digestive tract.
There are two types of lung carcinoid tumors: typical and atypical.
Typical lung carcinoid tumors are a slow-growing type of cancer that are not associated with smoking and do not tend to spread beyond the lungs.
Some people do not experience symptoms, but shortness of breath, facial flushing, weight gain, and high blood pressure may develop due to hormonal involvement.
Atypical carcinoid tumors are more likely to spread and may be linked to smoking.
The main treatment for lung carcinoid tumors is surgery, but a doctor may also recommend chemotherapy, radiation therapy, or both.
This article will look at the symptoms, stages, and treatment of lung carcinoid tumors.
Lung carcinoid tumors — also known as pulmonary carcinoid tumors or lung neuroendocrine tumors — are a type of lung cancer that doctors sometimes call lung carcinoids. They are a rare, slow-growing type of lung cancer.
People start developing carcinoid lung tumors in a certain type of body cell called a neuroendocrine cell.
Neuroendocrine cells found in the lungs are like nerve cells found in the brain and spinal cord. They also act like hormone-making cells.
Neuroendocrine cells are not part of a single organ but are spread across different parts of the body. Within the lungs, neuroendocrine cells:
While there are different types of lung cancers, only cancers that develop from neuroendocrine cells in the lungs are called lung carcinoids.
Doctors have identified two types of lung carcinoid tumors: typical and atypical carcinoids.
About 25% of people with carcinoid lung tumors may not experience any symptoms. Doctors may find the cancer when testing a person for another medical condition.
Symptoms of carcinoid lung tumors may include:
According to the American Cancer Society, typical carcinoid tumors are the most common type of lung carcinoid tumors. Smoking does not seem to cause typical carcinoids in the lung.
Typical carcinoids grow slowly and do not usually spread beyond the lungs. They are considered stage 1a, low-grade because they do not spread easily.
Atypical carcinoids grow faster than typical carcinoids and may spread to other body organs. They develop more commonly in people who smoke compared with typical carcinoid lung tumors.
Doctors consider atypical carcinoids to be intermediate-grade tumors because of the risk of spreading.
Doctors use the tumor-node-metastasis (TNM) staging system to determine the progression of atypical lung carcinoids. This combines factors such as the size of the tumor and how far cancer has spread.
According to the American Cancer Society, researchers are unsure what causes carcinoid lung tumors.
Many of the factors that lead to more common lung cancer, called carcinomas, do not seem to cause carcinoid tumors.
Doctors may find early signs of carcinoid lung tumors when doing lung biopsies for other medical conditions.
"Tumorlets" in the lungs are small clusters of neuroendocrine cells that resemble lung carcinoid tumors. Most often, tumorlets do not develop into carcinoid tumors, but sometimes they do.
Researchers have identified certain alterations in chromosomes and genes of cells in carcinoid lung tumors that may affect how the cells function. It is not yet clear how these changes lead to tumor development.
Doctors are also unsure whether certain risk factors exist for lung carcinoid development. Some people who develop lung carcinoid tumors may not have any risk factors to explain their condition.
Risk factors for carcinoid lung tumors include:
Many of these risk factors are things that people cannot change.
Since doctors are unsure of the causes and risk factors of carcinoid tumors, it is unknown how to prevent this type of cancer.
Since about one-quarter of people with carcinoid lung tumors do not have any symptoms, doctors must use other tools to diagnose them.
Doctors will check for unusual hormonal features if they suspect a neuroendocrine tumor.
These include:
Bronchoscopy and biopsy are the gold standard for diagnosing carcinoid lung tumors. Bronchoscopy allows doctors to see the inside of the lungs. If a doctor detects an unusual growth, they can remove a sample for analysis.
Medical imaging can also help detect carcinoid lung tumors. According to a 2021 article, a chest X-ray may detect around 40% of carcinoid lung tumors. A CT scan or a PET scan may be more sensitive to these tumors.
When diagnosing carcinoid lung tumors, doctors must distinguish between typical and atypical tumors. This distinction is necessary for selecting the correct treatment.
People with lung carcinoids will need surgery to remove the tumor. For people with atypical carcinoids, this may be extensive. Surgeons may need to remove an entire lung.
Some people may need bronchoplasty, which involves repairing the bronchi of the lungs.
Additional therapy for advanced atypical lung carcinoids may include chemotherapy with or without radiation therapy.
Certain cancer societies also recommend additional therapy for atypical carcinoids with lymph node involvement.
According to a 2021 article, the most important factor that affects the outlook of carcinoid lung tumors is whether the cancer is typical or atypical.
Atypical lung carcinoids are more likely to spread to other parts of the body than typical lung carcinoids.
Other factors affecting the outlook are:
The relative chance of living at least another 5 years after a diagnosis of atypical carcinoids is 60%, while for typical carcinoids it is 90%.
Here are some questions people often ask about lung or pulmonary carcinoid tumors.
How serious is a carcinoid lung tumor?A typical carcinoid lung tumor is considered low-stage and low-grade, as it tends to grow slowly. An atypical carcinoid lung tumor, however, can spread more rapidly. Without treatment, it can be fatal.
What is the survival rate of carcinoid lung cancer?The relative chance of living at least another 5 years after a diagnosis of atypical carcinoids is 60%, while for typical carcinoids it is 90%.
Are lung carcinoid tumors curable?Typical lung carcinoids grow very slowly and often respond to minor surgery. Low-grade and small tumors often need only regular monitoring to ensure the tumor has not spread.
Atypical carcinoids, however, can be harder to resolve, particularly with a later-stage diagnosis.
Is a carcinoid tumor in the lung considered lung cancer?Lung carcinoid tumors — also called pulmonary carcinoid tumors or neuroendocrine tumors — are a type of lung cancer.
Lung carcinoid tumors develop from changes in neuroendocrine cells in the lungs. They may be typical or atypical.
Typical lung carcinoids are more common, and most do not spread outside the lungs. Atypical tumors may grow more quickly and spread to other parts of the body.
Doctors will diagnose carcinoid lung tumors using biopsies, blood and urine samples, and medical imaging. Once diagnosed, people may require surgery to remove the growth. Some doctors may recommend additional treatment.
Stage I (Early-Stage) Lung Cancer
SOURCES:
Photo Credit: Science Photo Library/Getty Images
National Cancer Institute: "NCI Dictionary of Cancer Terms."
Suresh, S. Ramalingam, MD, deputy director, Winship Cancer Institute, Emory University.
American Cancer Society: "Non-Small Cell Lung Cancer," "Non-Small Cell Lung Cancer Survival Rates," "Cancer Staging," "What Is Small Cell Lung Cancer?" "Non-Small Cell Lung Cancer Signs and Symptoms," "Treatment Choices for Non-Small Cell Lung Cancer, by Stage."
National Health Service (UK): "Diagnosis: Lung Cancer", "Symptoms: Lung Cancer."
Mayo Clinic: "Lung Cancer Diagnosis," "Lung Cancer."
Methods in Molecular Biology: "Epidemiology of Lung Cancer Prognosis: Quantity and Quality of Life."
Cedars-Sinai: "Lung Cancer."
UpToDate: "Screening for lung cancer," "Overview of the initial evaluation, diagnosis, and staging of patients with suspected lung cancer."
Cancer Research UK: "Stage 1 lung cancer," "Survival for lung cancer."
Cancer.Net: "Just Diagnosed With Lung Cancer: Answers from an Expert."
Journal of Thoracic Disease:"Hyperfractionated and accelerated radiotherapy in non-small cell lung cancer."
What To Know About Metastatic Lung Cancer
Metastatic lung cancer is cancer that begins in the lungs and spreads to other areas. By the time lung cancer reaches metastasis, it is late stage and can be hard to treat, but outcomes vary between people.
Lung cancer often has no symptoms in its early stages.
According to a 2015 study, in approximately 30–40% of people with non-small cell lung cancer, the cancer had metastasized by the time it was diagnosed.
"Metastatic" refers to a stage, not a form of cancer. The name of cancer does not change when the disease affects a new area. For example, lung cancer that spreads to the liver is called metastatic lung cancer, not liver cancer.
This article looks at how lung cancer spreads to other organs, the effects on the body, and how doctors treat it.
What is the difference between small cell and non-small cell lung cancer?
Metastatic cancer has spread from one area of the body to another. For example, if cancer affects the bones of a person with lung cancer, it may have spread from the lungs to the bones. This is called metastatic lung cancer.
Metastatic lung cancer cells have the same features as the original lung cancer cells. A healthcare specialist called a pathologist can see this if they examine the cancerous tissue under a microscope.
Sometimes, however, doctors do not diagnose cancer before it spreads, and it is not possible to identify where it first developed.
In other cases, a person receives treatment for cancer in one area, and then their cancer spreads, becoming metastatic, after several years. This can occur even if tests no longer detect the original tumor.
Lung cancer may develop again in the same lung after successful treatment. This is called recurrent lung cancer.
If cancer develops in the other lung, it is metastatic if it has spread. Or it may be a new, separate case of lung cancer.
Learn about the types of lung cancer and how quickly they spread.
Metastatic cancer does not always cause symptoms. If they occur, the specific type of symptom depends on the affected body area.
Below, learn about areas that metastatic lung cancer commonly affects and some symptoms that may arise.
Adrenal glandsIf cancer has spread to the adrenal glands, it usually causes no symptoms. However, if the tumor is large, it may cause pain in the back or abdomen.
If cancer affects at least 90% of both glands, it can cause adrenal insufficiency. This can lead to symptoms such as:
BonesAround 35–40% of people with advanced lung cancer develop bone metastases. In this case, pain is the main symptom. The risk of fractures increases.
BrainAbout 40% of people with non-small cell lung cancer develop brain metastases. Symptoms include:
LiverSymptoms of metastatic lung cancer to the liver include:
Enlarged lymph nodes in the armpit, neck, and stomach can suggest that lung cancer has spread.
However, these nodes also swell in response to other health issues.
Learn about the different types of lung cancer.
Most cells have a limited life cycle. As they die, new ones form.
Lung cancer cells do not behave in this typical manner. They develop when cells in the lungs continue to multiply without dying.
The excess cells form a tumor. As the tumor grows, it needs more space, and it starts spreading to other areas. At this point, the cancer becomes metastatic.
Cancer cells spread in two ways, either by:
The National Cancer Institute notes that cancer cells can:
If lung cancer spreads, it typically invades areas such as the:
What are some other complications of lung cancer?
Testing for metastases involves checking the areas where lung cancer typically spreads.
Diagnostic testing involves:
Cancer that has metastasized throughout the body can be difficult to eliminate. Therefore, treatment focuses on controlling the growth of cancer and relieving symptoms.
The treatment options depend on the type of lung cancer, the location of the metastases, previous treatment, and the person's overall health.
Options include:
Preventing metastasisSome cancer treatments may help stop or slow metastasis by making conditions less suitable for the growth of cancer cells.
Anti-angiogenic drugs, for example, can stop tumors from growing their own blood vessels. Cutting off the supply of blood to the tumor can slow or prevent its growth.
Tyrosine kinase inhibitors (TKIs) prevent or reduce tumor growth by blocking growth signals within or between cancerous cells.
Meanwhile, scientists are investigating other ways to prevent cancer from spreading.
Healthy cells contain adhesion molecules that allow them to stick together. A 2019 study suggests that the loss of function in adhesion molecules may contribute to metastasis.
Scientists have also discovered that cancer cells secrete substances called exosomes that stimulate the cells to move. Research into the role of these exosomes in metastasis is ongoing.
It is not always possible to prevent lung cancer or keep it from spreading.
However, avoiding things that increase the risk of developing lung cancer can help. Smoking, for example, is a preventable risk factor.
Also, treatment is more likely to be effective in the early stages. Receiving a diagnosis and treatment early may prevent the cancer from spreading.
However, receiving an early diagnosis can be challenging because there are often no symptoms in the early stages. This is why screening is so important: It can detect lung cancer when treatment may be more successful.
Find tips for quitting smoking.
People with a high risk of lung cancer may wish to consider screening. It may be appropriate for people who:
Screening can help detect changes early when effective treatment can reduce or eliminate the cancerous cells before they spread.
The American Lung Association offers useful resources about accessing a lung cancer screening.
Read more about the stages of lung cancer.
What is the life expectancy of metastasized lung cancer?According to the American Cancer Society, people with non-small cell lung cancer that has spread to distant areas have a 9% chance of surviving another 5 years after diagnosis compared with people who do not have the cancer.
For those with small cell lung cancer that has spread to distant areas of the body, this figure is around 3%.
Treatments can help manage symptoms and improve a person's quality of life. In some cases, treatments may also slow the development of the cancer and help extend the person's life.
Learn more about the prognosis for late stage lung cancer.
Does metastatic lung cancer mean terminal?Metastatic lung cancer is also known as advanced lung cancer.
Advanced cancer cannot usually be cured. Therefore, it is considered a terminal illness.
However, treatment might control it, help relieve symptoms, and improve a person's quality of life for some time.
What are the first signs of metastatic lung cancer?Possible first symptoms of metastatic lung cancer include:
Treatments and lifestyle adjustments can help enhance the comfort and quality of life of someone with metastatic lung cancer.
The support of friends, family, and healthcare professionals can help a person manage the emotional effects and practical challenges of living with cancer.
Specifically, a person may benefit from:
A healthcare professional can often help locate appropriate counseling services and support groups.
In addition, the American Lung Association provides a directory of support groups and other resources.
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