WHAT IS CANCER
The human cell: a basic building block
The basic building block of the body is a structure called the cell. All organs such as the intestine, pancreas or liver are formed from millions of cells. Normal cells grow, divide and die in an orderly fashion. Most of the growth usually occurs in the early part of childhood. In a mature adult, cells in most part of the body divide to form new cells only to replace worn out or dying cells or to repair injury to the tissues.
Our genes regulate the growth of normal cells in the body. In every cell there are genes that stimulate growth of the cell and genes that stop the growth of the cells. In normal cells there is a balance in the growth genes and genes that stop growth and therefore uncontrolled growth of the cells is prevented.
Abnormal growth of the cell and cancer
When the normal mechanisms for regulating growth of cells in our body are disturbed then cells begin to grow in an uncontrolled fashion. This situation arises when the genes that regulate growth of normal cells are damaged giving rise to abnormal genes with disturbed functions. Cancer cells develop because of damage to the DNA. This damage to the DNA leads to loss of genes that stop growth and activate genes that stimulate growth.
A cancer develops when normal cells in the body begin to develop an abnormal growth pattern. Cancer cells are different from normal cells. In cancer cells, the genes that control growth are abnormal, causing uncontrolled growth of the cells. The uncontrolled rapid growth of cancer cells leads to formation of cancerous tumor.
DNA damage cause cancer
A cancer cell is analogous to motor vehicle driver who is driving a car with his foot continuously on the accelerator and complete loss of his brake function. The DNA changes in cancer are often a consequence both of inherited genetic abnormalities and environmental induced damage to the DNA. For example sunlight or chemical carcinogens contribute to changes in the DNA that give rise to cancer.
Cancer and metastasis
Cancer cells often detached from their primary site and travel to other parts of the body where they begin to grow new tumor deposits. This process is called metastasis that occurs when the cancer cells invade into the blood stream or into the lymph nodes. For example a cancer of the pancreas may give rise to cells that travel in the blood and go to the liver and develop metastatic tumors in the liver.
Different types of cancers can behave very differently. For example cancer arising in the Ampulla Vater of the duodenum can present in a manner very similar to that of pancreatic cancer, however the outcome of cancer of the ampulla vater is significantly better compared to pancreatic cancer.
What are the risk factors for cancer?
Risk factors for cancer include a patient’s family and genetic background and cancer causing factors in the environment. Tobacco and alcohol use are important risk factors for pancreatic cancer. Cigarette smoking is most important risk factor for the development of pancreatic cancer.
How is cancer treated?
Most cancers are treated with some combination of surgery, chemotherapy and radiation therapy. Surgery is usually the treatment of choice for most cancers if the cancer appears localized to the organ. The initial work up of a patient with cancer often involves staging the extent of disease to determine whether the tumor is removable by surgical means.
Important principles of cancer surgery include complete removal of primary cancer. This often includes removal of the lymph nodes to which the primary tumor may spread. An adequate surgical procedure should include a pathological examination of the cut margin of the tissue that is removed at the time of surgery to ensure that the tumor has been completely removed.
While preoperative staging with imaging studies often provides an accurate assessment of the extent of disease and the amount of body tissues that would be removed during the surgery, in many patients the success of the surgery often depends on the finding s of the surgeon at the time of surgery.
With a new CT technology today more than 90% of patients would have their tumor removed at the time of surgery if the preoperative CAT scan suggests that the tumor was localized to the organ and removable.
Radiation therapy is used for localized cancer. Radiation therapy destroys or damages cancer cells by targeting high energy x-rays to the tissues. Radiation therapy is usually painless and is provided in an out patient setting. For most tumors in the pancreas and biliary system a six-week course of radiation is often required and the treatments are given daily during this period.
Chemotherapy treatment is often combined with radiation to make the radiation treatment more effective. Most patients who undergo surgery for pancreatic and bile duct cancer will receive chemotherapy and radiation therapy after the surgery to reduce the chances for future recurrence of the tumor.
While surgery and radiation therapy are utilized to treat localized cancers, chemotherapy is used to treat cancers that have spread to other parts of the body. After a cancer is removed by surgery, chemotherapy can also decrease the risks of the cancer returning. Chemotherapy is often combined with radiation therapy in pancreatic cancer to reduce the chance of a tumor recurring.
The chemotherapy drugs that are often used in pancreatic and bile duct cancers include 5-flourouracil, leukovorin and gemcitidine. These drugs are usually well tolerated by the patient and are not associated with side effects such as loss of hair that is found with other chemotherapy agents.
Occasionally with advanced pancreatic tumors the chemotherapy and radiation therapy may be given up front initially to reduce the size of the tumor following which the patient is reevaluated for surgery. Chemotherapy is also utilized to treat patient who have metastatic pancreatic or bile duct cancer. Gemcitidine is usually the drug that is most often used. Gemcitidine may reduce the pain and improve the performance status of patients with advanced metastatic pancreatic and bile duct cancers.
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