This article is an overview of lung cancer types and causes. It will also discuss stages and treatment.
Lung cancer is cancer that starts in lung cells. Lung cancer can start in the cells lining the airways — the bronchial tubes. These tubes branch into smaller and smaller tubes known as bronchioles. Alveoli are tiny sacs at the end of bronchioles. Cancer can also start in these areas.
Cancer cells continue to grow and divide when regular cells would not. Cancer cells can form solid tumors and spread to other parts of the body.
Lung cancer is the third most common cancer in the United States, according to the
The two main types of lung cancer are NSCLC and SCLC.
Your medical team will diagnose the type of lung cancer by collecting a sample and looking at the cells under a microscope.
Learn about diagnostic tests for lung cancer.
NSCLC is the most common type of lung cancer — accounting for
Subtypes include:
- Adenocarcinoma: This is the most common subtype. It starts from cells that line the alveoli and secrete mucus. Doctors tend to find it in the outer parts of the lung. It is more likely than other subtypes and SCLC to be found before it has spread. Smoking is the most common cause. However, adenocarcinoma is the most common form of lung cancer in people who have never smoked, according to the ACS.
- Squamous cell carcinoma: This subtype starts in squamous cells that line the airways. Smoking is the main cause of squamous cell lung cancer. Doctors tend to find this cancer in the center of the lungs.
- Large cell (undifferentiated) carcinoma: This subtype can develop from large cells in the airways. It grows and spreads quickly, so doctors may treat it differently than other NSCLC subtypes. Large cell carcinoma includes large cell neuroendocrine carcinoma, which is similar to SCLC.
Stages and treatment
NSCLC treatment depends on the stage and certain biological markers in the cancer cells. Clinicians use imaging tests and other tests to gather this information.
There are five stages of NSCLC, from 0–4. The higher the number, the more advanced the cancer.
Stage 1 and 2 are what clinicians may describe as early stage cancers, per the National Comprehensive Cancer Network (NCCN). Stage 3 is locally advanced, which means the cancer has spread into the lung tissue and may have spread to nearby lymph nodes. Stage 4 is advanced lung cancer. Another name for it is metastatic lung cancer.
Sometimes, early stage cancers are cured. Locally advanced cancers are rarely cured, says the NCCN. There is no cure for metastatic lung cancer.
However, all lung cancers can be treated to slow or stop cancer growth, ease symptoms, and extend life.
The
- surgery
- chemotherapy
- radiation therapy
- targeted therapy
- immunotherapy
Learn more about NSCLC treatment.
SCLC accounts for
SCLC grows faster and spreads earlier than NSCLC. Per the ACS, in about 70% of people who receive a diagnosis of SCLC, the cancer has already spread outside the lung.
Smoking is the main cause of SCLC.
Stages and treatment
Doctors most often use a two-stage system for SCLC:
- Limited stage: These cancers are on one side of the chest. Radiation therapy is a common treatment intended to cure the cancer, explains the NCCN. Chemotherapy, immunotherapy, and surgery may be options as well.
- Extensive stage: These cancers have spread across to the other lung or distant parts of the body. Doctors may treat this stage with chemotherapy or immunotherapy, or both. There are some uses for radiation and surgery as well.
Learn more about SCLC staging and treatment.
Lung carcinoid tumors begin in neuroendocrine cells. They account for
Staging and treatment
Most doctors use only two stages to describe lung carcinoid tumors:
- Resectable stage: Surgery may be done to remove the cancer at this stage and
may cure it Trusted Source American Cancer Society Highly respected international organization Go to source . - Unresectable stage: Surgery cannot completely remove these cancers. Or, you may not be healthy enough for surgery. Radiation therapy is the usual treatment. Chemotherapy is not as useful for carcinoid tumors because they grow slowly. It is more effective for tumors that grow quickly.
Other lung tumors
These include:
- primary lung lymphoma
- sarcoma, cancer that starts in bones and soft tissues like muscles and blood vessels
- benign tumors, which are not cancerous
Lung metastases: Cancers that spread to the lungs
Nearly any type of cancer can spread — metastasize — to the lung. Per the ACS, the
- breast cancer
- colon cancer
- rectal cancer
- head and neck cancer
- kidney cancer
- testicular cancer
- uterine cancer
- lymphoma
When cancer metastasizes to the lung, it is still the primary cancer. For example, breast cancer that spreads to the lungs is not lung cancer. It is breast cancer.
Adithya Cattamanchi, M.D., reviewed the following questions.
What is the most serious type of lung cancer?
Clinicians consider SCLC the most aggressive type of lung cancer because it
Does lung cancer spread quickly?
Yes, lung cancer spreads quickly. A 2021 study in the Journal of Thoracic Oncology estimates that most lung cancers spread approximately 2.74 years before clinical detection, based on computer modeling. Tumors may spread to the lymph nodes earlier.
Which is worse: Right or left lung cancer?
For NSCLC, there does not appear to be a significant difference in overall survival or cancer-specific survival for cancer in the left versus right lung, according to a
What organs does lung cancer spread to?
Lung cancer commonly spreads to the liver, adrenal glands, bone, brain, and other lung.
NSCLC is the most common type of lung cancer, followed by SCLC and lung carcinoid tumors. Knowing the type and stage of the cancer is important for treatment decisions. The outlook for a cure is more favorable for NSCLC and lung carcinoid tumors than SCLC. Although, in general, it is difficult to cure lung cancer.
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