Lung cancer is a disease caused by the rapid growth and division of cells that make up the lungs. Lung cancer is sometimes called "bronchogenic cancer,"or it may be described by its particular histologic type, that is the type of tissue that is diseased.
Under normal circumstances, lung cells reproduce in an orderly fashion to maintain tissue health and to repair injuries. However, when growth control is lost and cells divide too much and too fast, a cellular mass—or tumor—is formed. If the tumor is confined to a few cell layers (for example, surface cells) and it does not invade surrounding tissues or organs, it is considered benign. By contrast, if the tumor spreads to surrounding tissues or organs, it is considered malignant, or cancerous.
If cancerous cells break away from the original tumor, travel, and grow within other body parts—such as the brain, bone, liver, adrenal glands, the opposite lung, or lymph nodes of the chest or collarbone (clavicle) regions—the process is known as metastasis.
Types of Lung Cancer
There are 2 main types of lung cancer. Each type grows, spreads and is
treated differently.
• Non-Small Cell Lung Cancer
This is the most common type of lung cancer. It grows and spreads
more slowly.
• Small Cell Lung Cancer
This type of lung cancer grows and spreads more quickly.
Symptoms of Disease
In many cases, the symptoms of lung cancer fail to appear until lung cancer has spread. Many of the symptoms of lung cancer are shared by other disease processes that may affect the body as well, making lung cancer detection difficult. The following symptoms and conditions may be present in those with lung cancer:
In many cases, the symptoms of lung cancer fail to appear until lung cancer has spread. Many of the symptoms of lung cancer are shared by other disease processes that may affect the body as well, making lung cancer detection difficult. The following symptoms and conditions may be present in those with lung cancer:
- Severe and persistent cough
- Presence of blood in sputum
- Chest, shoulder and back pain
- Chronic pneumonia or bronchitis
- Change in color and/or volume of sputum
- Shortness of breath
- Chronic fatigue
- Unexplained weight loss
- Loss of appetite
- Excessive bone and joint pain
Lung Cancer Diagnosis
Because lung cancer often goes unnoticed until the cancer has invaded other regions of the body, creating new techniques capable of detecting lung cancer early are a top priority of researchers. Currently, no reliable, cost-effective screening techniques have been approved for the early detection of lung cancer.
Diagnostic tests include the following:
- Chest radiograph (x-ray) is used to detect enlarged lymph nodes in the chest or a localized mass in the lungs.
- Computed tomography(CT or "CAT" scan) is a computer-assisted technique that produces cross-sectional images of the body.
- Magnetic Resonance Imaging(MRI scan) is a diagnostic method in which hydrogen ions within the body (and/or specific body parts) are excited by exposure to a magnetic field. The resulting signals are processed by a computer to create an image of the chest to define the location and extent of lung involvement.
- Bronchoscopy is a visual examination of the windpipe and lung branches performed by a pulmonologist (respiratory disease specialist) using a flexible scope. Bronchoscopy may involve brushings (using a small, brush-like device to gather cells from the tissue lining the respiratory system), washings of the respiratory tissues for cell analysis, and biopsy (removal and examination of small amounts of tissue). If the bronchoscopy is still unrevealing, or "negative," a needle biopsy may be performed.
- Needle biopsy, with CT-guidance, may be performed on suspicious areas in the lungs or pleura. Fine needle aspiration (FNA) uses a slim, hollow needle that is attached to a syringe. The needle is inserted into the suspicious mass and it is pushed back and forth to free some cells, which are aspirated (drawn up) into the syringe and are smeared on a glass slide for analysis. Large needle, or core biopsy, uses a large-bore needle to obtain a tissue sample for analysis.
- Bone scan may also be performed to rule out suspicions of metastasis to the bones. Metastasis is the process wherein cancerous cells break away from the original tumor, travel, and grow within other body parts.
Additional blood tests may be performed to look for lung cancer "markers"—that is, elements in the blood that are associated with the presence of lung cancer. For example, lung cancer may be indicated by abnormalities in the following.
- PTH (parathyroid hormone)—Blood levels of PTH or PTH-related protein may help to distinguish lung cancer from cancer of the pleura or other diseases.
- CEA (carcinogenic antigen)—a cancer-specific immune system protein that is present in many adenocarcinomas, including lung adenocarcinoma. Increased preoperative levels of CEA usually suggest a poor prognosis. A CEA level greater than 50 may indicate advanced stage lung cancer and should discourage treatment by resection.
- CYFRA21-1 (cytokeratin fragment 19)—a protein marker of lung cancer.
Lung Cancer Treatment
Treatment for lung cancer depends upon a variety of factors. The most important factors are the histopathologic (diseased tissue) type of lung cancer and the stage of the cancer.
Surgery
Surgery is considered the first line of treatment for localized non-small cell lung cancer (NSCLC) and lung carcinoid tumors. The more aggressive the spread of cancer in the lungs, the more aggressive the surgery to remove cancer will be.
Surgery is considered the first line of treatment for localized non-small cell lung cancer (NSCLC) and lung carcinoid tumors. The more aggressive the spread of cancer in the lungs, the more aggressive the surgery to remove cancer will be.
- Segmentectomy: removal of cancer and a small portion of surrounding lung tissue
- Lobectomy: removal of an entire lobe of lung
- Pneumonectomy: removal of the entire lung
Alternative approaches include anterior limited thoractomy (ALT), which is performed on the frontal chest using a small incision; anterioraxillary thoracotomy (AAT), which is performed on the frontal chest near the underarm; and posterolateral thoracotomy (PLT), which is performed on the back/side region of the trunk.
Surgery is rarely used in the treatment of small cell lung cancer because of its rapid spread to surrounding tissues and lymph nodes. If, however, SCLC is caught before it spreads, surgery may be used.
Radiation
Radiation therapy fights cancer by damaging cancer cells with a powerful beam of energy typically used in combination with anti-cancer drugs and/or surgery to clear any residual cancer that has not been destroyed by other methods.
Radiation therapy fights cancer by damaging cancer cells with a powerful beam of energy typically used in combination with anti-cancer drugs and/or surgery to clear any residual cancer that has not been destroyed by other methods.
- External beam radiation: radiation from outside source is directed at location of tumors and surrounding lymph nodes
- While radiation oncologists direct the radiation at the cancer cells, some surrounding normal tissue may also be harmed by the therapy, and therefore, the dose of radiation is closely monitored by the oncologist.
- Brachytherapy: internal radiation from radioactive source (usually radioactive "seeds" or pellets) planted into lung tissue near cancer; often used in combination with external beam radiation
Chemotherapy
Chemotherapy, or medical anti-cancer drug treatment, attempts to halt uncontrolled cell division of cancer by destroying all rapidly dividing cells. Different chemotherapy drugs will be prescribed based upon the type and stage of lung cancer. Chemotherapy can be used as the first defense against lung cancer, in combination with radiation (chemoradiation) or as a follow-up to surgery (adjuvant chemotherapy).
Chemotherapy, or medical anti-cancer drug treatment, attempts to halt uncontrolled cell division of cancer by destroying all rapidly dividing cells. Different chemotherapy drugs will be prescribed based upon the type and stage of lung cancer. Chemotherapy can be used as the first defense against lung cancer, in combination with radiation (chemoradiation) or as a follow-up to surgery (adjuvant chemotherapy).
- Although chemotherapy techniques wipe out cancer cells, many normal, rapidly dividing healthy cells are also killed by these treatments. The death of healthy cells causes undesirable side effects for cancer patients such as hair loss, mouth sores, nausea, impaired resistance to infection, bruising and more.
- To lessen the harmful side effects caused by chemotherapy, researchers are working to develop ways to tailor anti-cancer drugs that specifically target cancer cells and interfere with the chemical processes that promote cancer growth.
- Cisplatin (Platinol®)
- Carboplatin (Paraplatin®)
- Paclitaxel (Taxol®)
- Docetaxel (Taxotere®)
- Gemcitabine (Gemzar®)
- Vinorelbine (Novelbine®)
- Irinotecan (Camptosar®)
- Etoposide
- Vinblastine
Additional drugs used in combination with chemotherapy:
- Targeted drug therapy that blocks the ability of cancer cells to grow by targeting a mutated protein within the cancer cell
- Erlotinib (Tarceva®) - tyrosine kinase inhibitor that blocks the activity of the epidermal growth factor receptor (EGFR)
- Angiogenesis inhibitors: drugs that prevent tumors from accessing blood vessels, shutting tumors off from accessing nutrients and oxygen
- Bevacizumab (Avastin®): blocks vascular endothelial growth factors (VEGF), a protein that helps tumors to build blood vessels
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