This page was reviewed under our medical and editorial policy by
Peter Baik, DO, Thoracic Surgeon.
This page was updated on March 7, 2023.
Adenocarcinoma is the term for cancer that forms in a particular type of cell, called a glandular or secretory cell. These cells can be found inside the lining of some organs, helping to produce and secrete bodily fluids, including mucus or digestive juices. Adenocarcinoma, a common form of cancer, is the most common subtype of lung cancer, as well as most cancers in the breasts, esophagus, stomach, colon-cancer, rectum, uterus, pancreas and prostate.
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Most lung cancers are non-small cell lung cancers (NSCLC), and most non-small cell lung cancers are adenocarcinomas. This form of lung cancer accounts for more than 30 percent of all lung cancers and about half of all non-small cell lung cancers. In the United States, adenocarcinoma is more common than any other kind of lung cancer. Adenocarcinoma is usually found in the outer region of the lungs, and it grows more slowly than other types of lung cancer. It’s more likely than other types of NSCLC to be found before it has spread.
Adenocarcinoma of the lung forms when cells lining the outside of the lungs become cancerous. According to the American Society of Clinical Oncology, this form of lung cancer accounts for nearly 40 percent of all non-small cell lung cancers (NSCLC).
Adenocarcinoma forms in glands that secrete mucus. Other than the lungs, adenocarcinoma is most prevalent in cancers found in the prostate, pancreas, esophagus, colon and rectum. In the lungs, adenocarcinoma tumors most often form in the alveoli, the tiny balloon-like sacs that help pump air in and out of the lungs.
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Smoking is the No. 1 cause of all lung cancers—with about eight of 10 lung cancer deaths thought to be directly linked to smoking, according to the American Cancer Society (ACS). While lung adenocarcinoma is usually caused by smoking, it’s also the most common kind of lung cancer found in nonsmokers. More women than men develop lung adenocarcinoma, and it’s also found in younger people more often than other lung cancers.
Several risk factors may increase your risk of developing lung adenocarcinoma, some of which are within your control. In addition to smoking, exposure to secondhand smoke, radon, diesel exhaust, chromium compounds, beryllium, nickel, soot, tar or asbestos may increase the risk of developing adenocarcinoma and other types of NSCLC. Being exposed to high levels of arsenic in your drinking water, having human immunodeficiency virus (HIV) or taking beta carotene supplements (if you smoke) may also increase risk.
Other risk factors aren’t in your control, including air pollution, certain types of previous radiation therapy, and a personal or family history of lung cancer.
Lung adenocarcinoma may have a genetic element. For example, you may have inherited genetic mutations—such as changes to chromosome 6 or the EGFR gene—that are linked to an increased risk. Acquired genetic changes may occur from exposure to environmental elements that cause lung cell mutations, but they also may be completely random, with no direct cause.
The symptoms of adenocarcinomas in the lung include:
It’s important to note that adenocarcinoma of the lung may not cause any symptoms, especially early on. In some patients, lung adenocarcinoma is detected during a scan or imaging test of the chest region for a reason unrelated to lung cancer. What’s more, many of the signs of adenocarcinoma may mimic other conditions, so it’s important to reach out to your doctor if you’re experiencing any of the above.
Your doctor will first perform a physical examination and gather your personal and family health history, as well as ask about any symptoms you’re experiencing. If you’re a smoker, you have a relative who has had lung cancer, or you’ve been exposed to known carcinogens, be sure to let your doctor know. From there, you may undergo one or more of the following diagnostic tests:
Laboratory testing: Samples of your blood, urine and other bodily substances may be collected and sent to a lab to be evaluated and help your doctor diagnose adenocarcinoma. These tests may also offer insight into treatment options.
Imaging: An X-ray, magnetic resonance imaging (MRI) or computed tomography (CT) scan may be performed to screen for an abnormal mass in the lungs. An X-ray is a useful way for your doctor to view the lungs and other organs in your chest. If more detailed images are needed, a CT scan utilizes the help of a radioactive dye. When injected into your body or taken orally, the dye allows the area of concern to show up clearly on images. MRI scans are more likely to be used to check for the spread of lung cancer to the brain or spinal cord.
Sputum cytology: In this lab test, a sample of sputum (mucus coughed up from the airways) is tested for cancer cells. The sample is evaluated by a pathologist.
Thoracentesis: A thin needle is used to extract a fluid sample from between your lung and chest lining. This fluid is then examined by a pathologist to determine whether cancerous cells are present.
Biopsy: If your doctor suspects lung cancer based on your combined test results, a small sample of lung tissue will be removed and examined by a pathologist. A biopsy may be obtained via one of the following methods.
After diagnosing adenocarcinoma of the lung, doctors use the same diagnostic and other tests to determine the cancer’s stage. Lung adenocarcinoma is assigned a stage based on its location, whether it’s spread beyond the original site and the location of the spread. Staging plays a vital role in treatment, since lung adenocarcinoma may be treated more or less aggressively depending on its stage. A cancer’s stage also helps inform the patient’s prognosis.
Adenocarcinoma of the lung and other types of NSCLC are grouped into five stages.
Stage 0 or in situ: In stage 0, the cancer is “in situ” or “in place,” meaning it’s only found in the outer lining of the lung, and it hasn’t grown deeper into or spread outside of the lung.
Stage 1: In stage 1, the cancer has formed a small tumor, but it hasn’t spread to any lymph nodes outside the lung.
Stage 2: In stage 2, the cancer may or may not have spread farther into the lung or to nearby tissue or lymph nodes, but it hasn’t reached distant lymph nodes or distant parts of the body. Stage 2 contains two sub-stages, stage 2A and stage 2B, based on clearly defined criteria for the size of the tumor and where the cancer has spread. Stage 2B is more advanced than stage 2A.
Stage 3: In stage 3, the cancer may have spread farther into the lung or nearby tissue or lymph nodes, but it hasn’t reached distant lymph nodes or distant parts of the body. Stage 3 contains three sub-stages—stage 3A, stage 3B and stage 3C—progressing from least to most advanced. Each sub-stage has clearly defined criteria for the size of the tumor and where the cancer has spread.
Stage 4: In stage 4, the cancer may have spread to the other lung, nearby fluid, distant lymph nodes or distant organs. Stage 4 contains two substages, stage 4A and stage 4B. In stage 4A, the cancer has formed a tumor outside the chest. In stage 4B, it’s spread to more than one organ or to multiple places in one organ.
Treatment options for adenocarcinoma of the lung vary depending on the patient’s condition and needs. These treatment options may be delivered alone or in combination. Treatment options include:
Surgery: Whenever possible, the adenocarcinoma tumor is surgically removed from the lung. A combination of factors—including your overall health, the size and location of the tumor, and your pulmonary function—will help determine the most appropriate lung surgery option for you. No matter which type of surgery you have, lymph nodes near the tumor may also be removed to test for cancer.
The length of your overall recovery may take weeks or months and greatly depends on your overall health, as well as the type of surgery you had. It’s normal to stay in the hospital five to seven days after lung cancer surgery.
Possible complications of surgery include blood clots in the lungs or legs, wound infections, excess bleeding, reactions to the anesthesia or pneumonia.
Radiation therapy: Radiation treatment for NSCLC uses high-energy rays to either destroy cancer cells or prevent them from growing. One type of radiation therapy used to target adenocarcinoma tumors is external beam radiation therapy, which sends radiation from outside the body inward to the area affected by cancer. Stereobody radiation therapy or stereotactic radiosurgery (SRS) treats a lesion using a focused radiation beam minimally affecting the surrounding tissue. Brachytherapy, also known as internal radiation therapy, involves injecting a radioactive substance with a bronchoscope directly into the tumor or near the area where the cancer is located. Radiation therapy may be given after cancer surgery in order to help prevent a recurrence.
Immunotherapy: Drugs called checkpoint inhibitors help the immune system better identify and attack cancer cells.
Chemotherapy: Chemotherapy drugs are designed to destroy cancer cells, either throughout the whole body or in a specific area. You may undergo chemotherapy before or after lung cancer surgery. Prior to surgery, it may help shrink your tumor, increasing the operation’s rate of success. Usually, chemotherapy drugs for lung cancer are administered intravenously, but the U.S. Food and Drug Administration has approved several oral chemotherapy drugs for lung cancer as well.
Targeted therapy: Targeted therapy utilizes drugs or other substances to help destroy specific cancer cells. This type of treatment may cause less damage to healthy cells than chemotherapy and radiation. Targeted therapies such as monoclonal antibodies, tyrosine kinase inhibitors (TKIs) and mammalian target of rapamycin (mTOR) inhibitors may be used in the treatment of NSCLC.
Survival rate depends on the lung cancer stage and prognosis. According to the American Society of Clinical Oncology:
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