Lung Cancer (cont.)
What are the types of lung cancer?
Lung cancers, also known as bronchogenic carcinomas (carcinoma is another term for cancer), are broadly classified into two types: small cell lung cancers (SCLC) and non-small cell lung cancers (NSCLC). This classification is based upon the microscopic appearance of the tumor cells themselves. These two types of cancers grow and spread in different ways and may have different treatment options, so a distinction between these two types is important.
SCLC comprise about 20% of lung cancers and are the most aggressive and rapidly growing of all lung cancers. SCLC are strongly related to cigarette smoking, with only 1% of these tumors occurring in nonsmokers. SCLC metastasize rapidly to many sites within the body and are most often discovered after they have spread extensively. Referring to a specific cell appearance often seen when examining samples of SCLC under the microscope, these cancers are sometimes called oat cell carcinomas.
NSCLC are the most common lung cancers, accounting for about 80% of all lung cancers. NSCLC can be divided into three main types that are named based upon the type of cells found in the tumor:
- Adenocarcinomas are the
most commonly seen type of NSCLC in the U.S. and comprise up to 50% of NSCLC .
While adenocarcinomas are associated with smoking like other lung cancers,
this type is observed as well in nonsmokers who develop lung
cancer. Most adenocarcinomas arise in the outer, or peripheral, areas of the
lungs. Bronchioloalveolar carcinoma is a subtype of adenocarcinoma that
frequently develops at multiple sites in the lungs and spreads along the
preexisting alveolar walls.
- Squamous cell carcinomas
were formerly more common than adenocarcinomas; at present, they account for
about 30% of NSCLC. Also known as epidermoid carcinomas, squamous cell cancers
arise most frequently in the central chest area in the bronchi.
- Large cell carcinomas,
sometimes referred to as undifferentiated carcinomas, are the least common
type of NSCLC.
- Mixtures of different types of NSCLC are also seen.
Other types of cancers can arise in the lung; these types are much less common
than NSCLC and SCLC and together comprise only 5%-10% of lung cancers:
- Bronchial carcinoids
account for up to 5% of lung cancers. These tumors are generally small (3-4 cm or less) when diagnosed and occur most commonly in people under 40 years of age. Unrelated to cigarette smoking, carcinoid tumors can metastasize, and a small proportion of these tumors secrete hormone-like substances that may cause specific symptoms related to the hormone being produced. Carcinoids generally grow and spread more slowly than bronchogenic cancers, and many are detected early enough to be amenable to surgical resection.
- Cancers of supporting lung tissue such as smooth muscle, blood vessels, or
cells
involved in the immune response can rarely occur in the lung.
As discussed previously, metastatic cancers from other primary tumors in the
body are often found in the lung. Tumors from anywhere in the body may spread to
the lungs either through the bloodstream, through the lymphatic system, or
directly from nearby organs. Metastatic tumors are most often multiple,
scattered throughout the lung, and concentrated in the peripheral rather than
central areas of the lung.
Next: What are the signs and symptoms of lung cancer? »
- granisetron transdermal system (patch), Sancuso - Learn about granisetron transdermal system (patch) (Sancuso), prescribed for the prevention of nausea and vomiting as a result of chemotherapy cancer treatment. Side effects, drug interactions, and dosage information is included.
- CT Scan (Computerized Axial Tomography) - CT Scan (Computerized Axial Tomography, CAT scan) is a procedure that assists in diagnosing tumors, fractures, bony structures, and infections in the organs and tissues of the body.
- Bronchitis - Learn about bronchitis an inflammation of the lining of the lungs. Bronchitis can be aggravated from colds, cigarette smoking, COPD, and other lung conditions.
Latest Medical News
Cancer RSS