Cancer

Cancer (medical term: malignant neoplasm) is a class of diseases in which a group of cells display uncontrolled growth (division beyond the normal limits), invasion (intrusion on and destruction of adjacent tissues), and sometimes metastasis (spread to other locations in the body via lymph or blood). These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, do not invade or metastasize. Most cancers form a tumor but some, like leukemia, do not. The branch of medicine concerned with the study, diagnosis, treatment, and prevention of cancer is oncology.
Cancer may affect people at all ages, even fetuses, but the risk for most varieties increases with age.[1] Cancer causes about 13% of all deaths.[2] According to the American Cancer Society, 7.6 million people died from cancer in the world during 2007.[3] Cancers can affect all animals.
Nearly all cancers are caused by abnormalities in the genetic material of the transformed cells. These abnormalities may be due to the effects of carcinogens, such as tobacco smoke, radiation, chemicals, or infectious agents. Other cancer-promoting genetic abnormalities may be randomly acquired through errors in DNA replication, or are inherited, and thus present in all cells from birth. The heritability of cancers are usually affected by complex interactions between carcinogens and the host's genome. New aspects of the genetics of cancer pathogenesis, such as DNA methylation, and microRNAs are increasingly recognized as important.
Genetic abnormalities found in cancer typically affect two general classes of genes. Cancer-promoting oncogenes are typically activated in cancer cells, giving those cells new properties, such as hyperactive growth and division, protection against programmed cell death, loss of respect for normal tissue boundaries, and the ability to become established in diverse tissue environments. Tumor suppressor genes are then inactivated in cancer cells, resulting in the loss of normal functions in those cells, such as accurate DNA replication, control over the cell cycle, orientation and adhesion within tissues, and interaction with protective cells of the immune system.
Diagnosis usually requires the histologic examination of a tissue biopsy specimen by a pathologist, although the initial indication of malignancy can be symptoms or radiographic imaging abnormalities. Most cancers can be treated and some cured, depending on the specific type, location, and stage. Once diagnosed, cancer is usually treated with a combination of surgery, chemotherapy and radiotherapy. As research develops, treatments are becoming more specific for different varieties of cancer. There has been significant progress in the development of targeted therapy drugs that act specifically on detectable molecular abnormalities in certain tumors, and which minimize damage to normal cells. The prognosis of cancer patients is most influenced by the type of cancer, as well as the stage, or extent of the disease. In addition, histologic grading and the presence of specific molecular markers can also be useful in establishing prognosis, as well as in determining individual treatments.

General Patient Selection Criteria for Extrapleural Pneumonectomy

Extrapleural pneumonectomy is a serious operation, and doctors experienced in this procedure choose their patients carefully. It is up to each individual surgeon to advise the patient on its feasibility and to conduct whatever tests he/she feel are necessary to optimize the patient's chances for survival and recovery. Following is a general list of patient selection criteria. This list may not be all inclusive, and may vary according to the preference of the surgeon.

Karnofsky Performance Status score of >70. This score relates to what symptoms of disease the patient may be experiencing and how well they are able to conduct their daily activities. Some surgeons may require a higher performance status than others.

Adequate renal (kidney) and liver function tests; no significant kidney or liver disease.

Normal cardiac function per electrocardiogram and echocardiography.

Adequate pulmonary function to tolerate the surgery.

Disease limited to the ipsilateral hemithorax (the same side of the chest in which the mesothelioma is located) with no penetration of the diaphragm, extension to the heart or extensive involvement of the chest wall.

Age of the patient is taken into consideration, but may not be as important as their overall status.

Surgeries of this nature should always be done with a complete understanding of the possible benefits and risks involved. If you are considering surgery as a treatment option, speak openly with your doctor about your concerns, and be sure all of your questions are answered to your satisfaction.

Treatment

Pleural effusion caused by heart failure or infection can usually be resolved by directing treatment at the cause, however, when testing has realized no diagnosis, and fluid continues to build or recur, doctors may recommend chest tube drainage and chemical pleurodesis. Chemical pleurodesis is a technique in which a sclerosing agent is used to abrade the pleural surfaces producing an adhesion between the parietal and visceral pleurae. This will prevent further effusion by eliminating the pleural space. Talc appears to be the most effective agent for pleurodesis, with a success rate of nearly 95%. It is highly effective when administered by either poudrage or slurry. Poudrage is the most widely used method of instilling talc into the pleural space. Before spraying the talc, the medical team removes all pleural fluid to completely collapse the lung. After the talc is administered, they inspect the pleural cavity to be sure the talc has been evenly distributed over the pleural surface. Some doctors prefer to use talc mixed with saline solution which forms a wet slurry that can roll around the pleural cavity.

Symptoms

As the volume of fluid increases, shortness of breath, known as "dyspnea", and sometimes pain, ranging from mild to stabbing, may occur. Some patients may experience a dry cough. When the doctor listens to the patient’s chest with a stethoscope, normal breath sounds are muted, and tapping on the chest will reveal dull rather than hollow sounds.

Types

Pleural effusion is broken down into two categories, transudates and exudates. A transudate is a clear fluid that forms not because the pleural surfaces are diseased, but because of an imbalance between the normal production and removal of the fluid. The most common cause of transudative fluid is congestive heart failure. An exudate, which is often cloudy and contains many cells and proteins, results from disease of the pleura itself, and is common to mesothelioma. To determine whether a fluid is a transudate or exudate, a diagnostic thoracentesis, in which a needle or catheter is used to obtain a fluid sample, may be conducted.

Pleural Effusion

One of the most common symptoms of mesothelioma is a pleural effusion, or an accumulation of fluid between the parietal pleura (the pleura covering the chest wall and diaphragm) and the visceral pleura (the pleura covering the lungs). Both of these membranes are covered with mesothelial cells which, under normal conditions, produce a small amount of fluid that acts as a lubricant between the chest wall and the lung. Any excess fluid is absorbed by blood and lymph vessels maintaining a balance. When too much fluid forms, the result is an effusion.

MESOTHELIOMA'S CAUSE - ASBESTOS EXPOSURE

At some point in our lives, nearly all of us have been exposed to asbestos in the air we breathe and the water we drink; from natural deposits in the earth, and from the deterioration of asbestos products around us. Most of us, however, do not become ill as a result of our exposure. More commonly, those who at some point are diagnosed with asbestos disease, have worked in jobs where more substantial exposure occurred over longer periods of time. Nevertheless, cases of mesothelioma have been documented as the result of lesser exposure, affecting family members of workers who came into contact with asbestos and brought it home on their clothing, skin or hair, or affecting those who lived in close proximity to asbestos manufacturing facilities. Symptoms of asbestos disease usually are not be apparent until decades after exposure.
Asbestos was used commercially in North America as early as the late 1800s, but its use increased dramatically during the World War II era when shipyards produced massive numbers of ships for the war effort. Since that time, asbestos-containing products were used by the construction and building trades, the automotive industry and the manufacturing industry. All told, more than 5,000 products contained asbestos.
For more than 50 years, products containing asbestos remained unregulated, and the manufacturers of those products continued to prosper, knowing full well that many of the millions of workers who came into contact with their products would ultimately suffer as the result of their actions. Finally, in the late 1970s, the Consumer Products Safety Commission banned the use of asbestos in wallboard patching compounds and artificial ash for gas fireplaces because the fiber could easily be released during use. In 1989, the Environmental Protection Agency banned all new use of asbestos, but uses established prior to that time were still allowed. Although awareness of the dangers of asbestos and public concern over the issue have led to a decline in domestic consumption over the years, a total ban on asbestos has not come to fruition. Asbestos is still imported, still used and still dangerous.