Adenocarcinoma of the lung

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 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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Causes and risk factors of lung adenocarcinoma

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 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.

Symptoms of adenocarcinoma of the lung

The symptoms of adenocarcinomas in the lung include:

• Persistent cough
• Shortness of breath
• Chest pain
• Raspy voice
• Fatigue
• Difficulty breathing or swallowing
• Wheezing
• Cough that produces mucus with blood
• Loss of appetite
• Facial swelling, or swelling in the veins of your neck
• Unexplained weight loss

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.

Learn more about the symptoms of lung cancer

Diagnosing adenocarcinoma of the lung

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 using a microscope.

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.

• Fine-needle aspiration (FNA): A biopsy of abnormal lung tissue or fluid is withdrawn using a long, thin needle to tests for the presence of lung cancer cells.
• Bronchoscopy: If your doctor needs to inspect areas of concern inside your lung airways, a bronchoscopy may be performed. A thin instrument with a lighted lens on the end, called a bronchoscope, will be guided through your mouth or your nose. A biopsy of suspicious tissue will be removed and tested for cancer.
• Thoracoscopy: A surgical incision is made between two of your ribs, and a thoracoscope is inserted into the chest cavity. This instrument has a lighted camera on the end that your doctor will use to check for any areas of concern. If abnormalities are found, a biopsy can be taken of the tissue or lymph nodes.
• Mediastinoscopy: In order to view the area between your lungs, an incision is made right at the top of your breastbone and a tool called a mediastinoscope is inserted. This tool has a lighted lens on the end that allows your organs, tissue and lymph nodes in the area to be examined. If necessary, a biopsy will be taken.
• Anterior mediastinotomy: A mediastinoscope is inserted into an incision near the breastbone to view the organs and tissues located between your breastbone and heart in detail. A tissue or lymph node biopsy may be taken.
• Lymph node biopsy: Doctors may test for cancer by removing all or a portion of a lymph node near the lungs. This helps your doctor determine whether the adenocarcinoma has spread.

Learn more about diagnostic procedures for lung cancer

Treatment for adenocarcinoma of the lung

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.

• Pneumonectomy: This surgery involves removing an entire lung and can only be performed if you have sufficient lung function in your remaining lung. It may be necessary if your tumor is very large, or if it’s located near the center of your chest.
• Lobectomy: This surgery is often the preferred surgical option for NSCLC. The lobe of your lung containing the tumor will be entirely removed (there are three lobes on the right lung and two lobes on the left lung).
• Segmentectomy or wedge resection: If your lung function isn’t strong enough for you to undergo a lobectomy, you may have one of these procedures instead. A wedge resection involves the removal of the tumor as well as a wedge-shaped area of tissue around it. In a segmentectomy, a slightly larger amount of surrounding tissue is removed.
• Sleeve resection: This operation entails removing a tumor from your lung along with a piece of your airway, or bronchus. The ends of the bronchus are then sewn back together, and any remaining lobe is reattached.

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. Radiation therapies used to target adenocarcinoma tumors include external beam radiation therapy, which sends radiation from outside the body inward to the area affected by cancer, and brachytherapy, also known as internal radiation therapy. With internal radiation therapy, a radioactive substance is injected 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 rates for adenocarcinoma of the lung

Survival rate depends on the lung cancer stage and prognosis. According to the American Society of Clinical Oncology:

• For localized NSCLC limited to the lung, the five-year survival rate is 63 percent.
• For those with NSCLC that has metastasized outside of the lung to nearby areas, the five-year survival rate is about 35 percent.
• If NSCLC has metastasized beyond the lungs and chest cavity to distant areas of the body, the five-year survival rate is 7 percent.

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