LUNG CANCER

Lung cancer:

Lung cancer is the leading cause of cancer deaths in women and men both in the United States and around the world. Lung cancer has surpassed breast cancer as the leading cause of cancer deaths in women. In the United States in 2010, 157,300 people were expected to die from lung cancer, which is more than the number of deaths from colon and rectal, breast and prostate cancer combined. Only about 2% of people diagnosed with lung cancer that has spread to other parts of the body life, five years after diagnosis, although the survival of lung cancer diagnosed in the earliest stages are higher, by about 49% survive for five years or more.

• Cancer occurs when normal cells undergo a transformation that causes them to grow and multiply without control. The cells form a mass or tumor that differs from the surrounding tissue from which it arises. Tumors are dangerous because they take oxygen, nutrients and space from healthy cells as they invade and destroy or ability to reduce the normal tissue to function.
• Most lung tumors are malignant. This means that they invade and destroy healthy tissues around them and can spread throughout the body.
• The tumors can spread to nearby lymph nodes or through the bloodstream to other organs. This process is called metastasis.
• When lung cancer metastasizes, the tumor in the lung is called the primary tumor, and tumors in other parts of the body are called secondary tumors or metastatic tumors.
• Some tumors in the lung metastatic cancer from elsewhere in the body. The lungs are a common site for metastasis. If this happens, the cancer is not considered to be lung cancer. For example, if prostate cancer spreads through the bloodstream to the lungs, the metastatic prostate cancer (a secondary cancer) in the lungs and it is not called lung cancer.
• Lung cancer is a group of different types of tumors. Lung cancer is usually divided into two main groups responsible for about 95% of all cases.
• The grouping is based on the type of cells that make up the cancer.
• The two main types of lung cancer are characterized by the cell size of the tumor when viewed under the microscope. They are called small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLC includes several subtypes of tumors.
• SCLCs are less common, but they grow faster and are more likely to metastasize than NSCLCs. Often, SCLCs have already spread to other parts of the body when the cancer is diagnosed.
• About 5% of lung cancers are of rare cell types, including carcinoid tumor, lymphoma, and others.

The specific types of primary lung cancer are as follows:

TYPES OF LUNG CANCER:

• Adenocarcinoma (an NSCLC) is the most common form of lung cancer, together 30% -40% of all cases. A subtype of adenocarcinoma is called bronchoalveolar cell carcinoma, which creates a pneumonia-like appearance on chest X-rays.
• Squamous cell carcinoma (NSCLC) is the second most common type of lung cancer, representing approximately 30% of all cases.
• Large cell cancer (another NSCLC) accounts for 10% of all cases.
• SCLC is 20% of all cases
• Carcinoid tumors account for 1% of all cases.
• Lung cancers, also known as bronchogenic carcinoma, are generally classified into two types: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). This classification is based on the microscopic appearance of the tumor cells themselves.These two cancers grow and spread in different ways and different treatment options, so a distinction between these two types is important.
• SCLC accounts for about 20% of lung cancers 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 in the body and are usually discovered after they have spread extensively. Referring to a specific cell appearance often seen in the examination of samples of SCLC under the microscope, these cancers may oat cell carcinoma
• NSCLC is the most common cancer, accounting for approximately 80% of all lung cancers. NSCLC can be divided into three main types listed according to the type of cells in the tumor.
• Adenocarcinomas are the most common form of NSCLC in the U.S. and include up to 50% of NSCLC. While adenocarcinomas are associated with smoking, like other cancer, this type is also observed in non-smokers who develop lung cancer. Most adenocarcinomas arise in the outer, or peripheral, regions of the lungs. Bronchioloalveolar carcinoma is a subtype of adenocarcinoma often develops in several places in the lungs and spreads along the existing alveolar walls.
• Squamous cell carcinomas were once more common than adenocarcinomas, at present, they account for about 30% of NSCLC. Also known as epidermoid carcinoma, squamous cell cancers occur most often in the central chest in the bronchi.
• Large cell carcinomas, sometimes referred to as undifferentiated carcinomas, are the least common form of non-small cell lung cancer.
• Mixtures of different types of non-small cell lung cancer are also seen.
• Other forms of cancer can occur in the lungs, these species are much less common than NSCLC and SCLC and together only 5% -10% of lung cancers:
• Bronchial carcinoids account for up to 5% of lung cancers. These tumors are generally small (3 cm-4 cm or less) in the diagnosis and occur most commonly in people younger than 40 years. Nothing to do with cigarette smoking, carcinoid tumors can metastasize, and a small portion of these tumors secrete hormone-like substances that can cause specific symptoms related to the hormone produced. Carcinoid tumors generally grow and spread more slowly than bronchogenic cancers, and many are discovered early enough to be amenable to surgical resection.

SYMTOMS AND SIGNS OF LUNG CANCER:

Symptoms of lung cancer are varied, depending on where and how widespread the tumor. Warning signs of lung cancer are not always present or easy to identify. A person with lung cancer symptoms, the following types:

There are no symptoms in up to 25% of people who have lung cancer, the cancer was first discovered on a routine chest X-ray or CT scan as a solitary small mass called a coin lesion, because a two-dimensional X -ray or CT scan, the tumor looks like a round coin. These patients with small single masses frequently report no symptoms when the cancer is detected.

Symptoms related to cancer: The growth of the cancer and the invasion of the lungs and surrounding tissue can interfere with breathing, leading to symptoms such as coughing, shortness of breath, wheezing, chest pain and coughing up blood (hemoptysis). If the cancer has invaded nerves, for example, can lead to shoulder pain that travels along the outside of the arm (called Pan coast Syndrome) or paralysis of the vocal cords resulting in hoarseness. Invasion of the esophagus can cause difficulty swallowing (dysphasia). If a large airway is blocked, it can collapse a part of the action and cause lung infections (abscesses, pneumonia) in the obstructed area.

Symptoms related to metastasis: Lung cancer that has spread to the bones can cause excruciating pain at the sites of bone involvement. Cancer that has spread to the brains can cause a number of neurological symptoms blurred vision, headaches, seizures, or symptoms of stroke such as weakness or loss of sensation in parts of the body.

Paraneoplastic symptoms: Lung Cancer is often accompanied by symptoms that result from the production of hormone-like substances by the tumor cells. These paraneoplastic syndromes occur most commonly with SCLC, but can be seen with any type of tumor. A common paraneoplastic syndrome associated with SCLC is the production of the hormone adrenocorticotropic hormone (ACTH) by the cancer cells, leading to over secretion of the hormone cortical  by the adrenal glands (Cushing's syndrome). The most common paraneoplastic syndrome seen with NSCLC is the production of a substance similar to parathyroid hormone, resulting in increased levels of calcium in the bloodstream.

Nonspecific symptoms: Nonspecific symptoms seen in many cancers, including lung cancer, including weight loss, weakness and fatigue. Psychological symptoms such as depression and mood swings are also common.