Mesothelioma - Primary Lung Cancer and Secondary Lung Cancer

Cancer is a disease related to the uncontrolled growth of tissue, leading to the accumulation of mass (called a tumor or lesion.) Normal cells in the body divide and grow in an orderly controlled manner. When cells grow uncontrollably and this growth invades other tissues or organs, the growths are called malignant or cancerous. When a mass of tissue, or tumor, is benign, it is relatively stable and does not invade other tissues.

Cells from malignant tumors can break away and travel to other parts of the body, usually through the bloodstream, but also through the lymph system. When these cells find new host organs, these cells can grow into tumors in the new tissue. This spreading process is called metastasis and when a cancer has reached an advanced stage to where the malignant cells are attacking other organs, it is said that the cancer tumors have metastasized. The tumors in new organs are always made up of cells similar to those of the original tumor.

Benign tumors do not metastasize. They can often times be removed through surgery and not re-occur.
Lung Cancer

Lung cancer occurs when lung tissue develops cancerous growths. Primary lung cancer is cancer that originates in the lung tissue. Secondary lung cancer is cancer that spreads, or metastasizes, from other organs.
Primary Lung Cancer

There are several different types of primary lung cancer. These are divided into two main groups:

* Small Cell Lung Cancer
* Non-small Cell Lung Cancer

Pleural mesothelioma is often thought of as a third type of primary lung cancer. However, it is not a lung cancer. Mesothelioma does not develop in the lungs, but in the serous membranes surrounding the lungs. As such, it does not fall into the typical categories of lung cancer. Mesothelioma can also occur in other tissues, in the lining of the abdomen, call peritoneal mesothelioma, and in the lining of the heart, pericardial mesothelioma.
Small Cell Lung Cancer

Small Cell Lung Cancer comprises approximately 20% of the primary types of lung cancer. It is called small cell cancer because the tumor cells are very small, with the cells containing almost exclusively the cell nucleus and nothing more. This type of cancer is also referred to as �oat cell� cancer. Chemotherapy is often suggested for this cancer in the early stages because of the rapid way it which it spreads. Surgery is not a good option to stop the spread early on. This type of cancer is most closely linked to smoking; non smokers rarely have it.
Non-Small Cell Cancer

Non-small cell cancer falls into these categories:

* Squamous cell carcinoma
* Adenocarcinoma
* Large cell carcinoma
* Adenosquamous cell carcinoma
* Undifferentiated carcinoma

Each category of non-small cell cancer are physiologically similar and they respond to treatment differently than to small cell lung cancer.

Squamous cell carcinoma is a common type of primary lung cancer. This type of cancer is also linked to smoking and it develops from the cells than line the airways in the lungs. Squamous cells are thin, flat cells that look like fish scales. Commonly the tumor growths are located in the center of the lungs near the large airways (bronchi). It is also referred to as epidermoid carcinoma. It comprises approximately 30 to 35% of the non-small cell cancer in the US, affecting men and the elderly most frequently.

Adenocarcinoma, like squamous cell carcinoma, develops from tissues in the lung airways. But, it develops from the glandular secretory tissues. (tissues that produce mucus). It is often found in the outer airway passages, not the main bronchi, like the squamous cell variety. The incidence of this cancer is increasing. It comprises about 40% of the non-small cell lung cancer in the US and is the most common lung cancer among women.

Large cell lung cancer is named after its appearance. The cells look large and unnatural under the microscope. These types of cells grow quite quickly.

Adenosquamous carcinoma are cells that appear flat under the microscope, like the squamous cells, but derive from the glandular secretory cells, like the adenocarcinoma.

Undifferentiated carcinoma includes cancer cells that cannot be identified as one of the other groups. The cells appear abnormal under the microscope and multiply uncontrollably.
Secondary Lung Cancer

Secondary lung cancer is cancer that has spread to the lungs from other organs. Many different types of cancer spread to the lungs, because of its very high blood supply. These include breast cancer and colon cancer.

The type of cancer is very important when it comes to treatment. The different types of cancer cells respond differently to different types of chemotherapy and other therapies. When cancer cells spread from other organs to the lungs, then the lungs have to be treated for the other type of cancer, not lung cancer. This is an important distinction. For example, breast cancer that spreads to the lungs, has to be treated for breast cancer, not lung cancer.

Mesothelioma Prognosis

Pleural mesothelioma is a difficult cancer to treat because it can spread so extensively and it is generally not diagnosed until it is in the more advanced stages, making surgical removal of all the cancer difficult or impossible. Because it is a relatively rare cancer, mesothelioma has not been studied as much as more common forms of cancer. The stage at which treatment for mesothelioma is begun has a tremendous impact on the patient’s prospects for long-term survival.

The American Cancer Society reports that some pleural mesothelioma patients in stage I have had their mesothelioma successfully removed through an involved surgical procedure called extrapleural pneumonectomy. Extrapleural pneumonectomy is a grueling surgery only offered to patients in otherwise good health. The entire affected lung plus the pleural lining of the chest wall, diaphragm, and pericardium on the affected side are removed. Surgeons then reconstruct the diaphragm and the pericardium. This procedure works best for patients with epithelioid cell mesothelioma.

Some patients who have had a successful extrapleural pneumonectomy are now enjoying long remissions. A study of 120 patients, who underwent extrapleural pneumonectomy at the Dana-Farber Cancer Institute in Boston between the years 1980 and 1995, revealed that 22 percent of these patients survived five years or longer. The surgery for these patients had been followed by chemotherapy and radiation (Cancer Help UK, 2008).

Removing most of the mesothelioma from patients in stage II and III in a procedure called pleurectomy/decortication may also increase a patient’s life expectancy. The aim of this procedure is palliative, as it can control fluid buildup and relieve pain and pressure.

Factors Influencing the Prognosis

The patient’s overall health status and age affect the prognosis. The American Cancer Society reports that 75 percent of those diagnosed with mesothelioma are 65 years old or older. Men are five times more likely to have mesothelioma than women are.

When mesothelioma is diagnosed, the doctors look at how far the cancer has spread and several health factors. Pleural mesothelioma patients have a poorer prognosis if they are experiencing chest pain, shortness of breath, inability to perform daily tasks, weight loss, a low red blood cell count, a high white blood cell count, and high blood levels of a substance called LDH. According to the American Cancer Society, most mesothelioma patients who have all these factors present pass away within six months of their diagnosis. It is rare for these seriously ill patients to live two years after their diagnosis. Patients without these serious risk factors at the time of their diagnosis have a better outcome.

Mesothelioma and Asbestos

While a rare disorder in the general population, mesothelioma is not rare among individuals exposed to asbestos. There are two to three thousand new diagnoses of mesothelioma every year.

Exposure to asbestos is the only confirmed cause of mesothelioma. Most mesothelioma victims were exposed to asbestos in the workplace and were never told of its dangers or given proper protective gear. Others were exposed through family members who brought asbestos home on their clothes or through home renovation projects. Unlike many other predominantly pulmonary-related cancers, cigarette smoking has no known causative effect on mesothelioma incidence, although asbestos workers who smoke do have a much greater likelihood to develop lung cancer — even more so than regular smokers who don’t work with asbestos.

One of the most difficult aspects of mesothelioma to come to terms with is its long latency period, which is the period of time between first exposure to asbestos and the onset of the disease. Mesothelioma can develop anywhere between 10 to 70 years after the initial exposure