Cancer

         Cancer is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues in our body. Cancer cells can break away and spread to other parts of the body by entering bloodstream or the lymphatic system.

        Cancer is not just one disease but many diseases. There are more than 100 different types of cancer. Most cancers are named for the organ or type of cell in which they start. For instance, cancer that begins in the colon is called colon cancer; cancer that begins in basal cells of the skin is known as basal cell carcinoma.

Cancer types can be grouped into broader categories. The main categories of cancer include:

§      Carcinoma

Cancer that begins in the skin or in tissues that line or cover internal organs.

§      Sarcoma

Cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.

§      Leukemia

Cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter the blood.

§      Lymphoma and myeloma

Cancers that begin in the cells of the immune system.

§      Central nervous system cancer

Cancers that begin in the tissues of the brain and spinal cord.

Origin of Cancer

            All cancer begins in cells which are the body’s basic unit of life. To understand cancer, it’s helpful to know what happens when normal cells become cancer cells.

         The body is made up of many types of cells. These cells grow and divide in a controlled way to produce more cells as they are needed to keep the body healthy. When cells become old or damaged, they die and are replaced with new cells.

         However, sometimes this orderly process goes wrong. The genetic material of a cell which is DNA can become damaged or changed, producing mutations that affect normal cell growth and division. When this happen, cells do not die when they should and new cells form when the body does not need them. The extra cells may form a mass of tissue called a tumor.

Not all tumors are cancerous. Tumors can be benign or malignant.

©       Benign tumors are not cancerous. They can often be removed, and, in most cases, they do not come back. Cells in benign tumors do not spread to other parts of the body.

©       Malignant tumors are cancerous. Cells in these tumors can invade nearby tissues and spread to other parts of the body. The spread of cancer from one part of the body to another is called metastasis.

The risk of developing many types of cancer can be reduced by practicing healthy lifestyle habits, such as eating a healthy diet, getting regular exercise, and not smoking. Also, the sooner a cancer is found and treatment begins, the better the chances are that the treatment will be successful. 

Cancer Staging

Staging describes the severity of a person’s cancer based on the extent of the primary tumor and whether or not cancer has spread in the body. Staging is important for several reasons:

• Staging helps the doctor plan the appropriate treatment.
• The stage can be used to estimate the person’s prognosis.
• Knowing the stage is important in identifying clinical trials that may be suitable for a particular patient.
• Staging helps health care providers and researchers exchange information about patients. It also gives them a common terminology for evaluating the results of clinical trials and comparing the results of different trials.

The common elements considered in most staging systems are as follows:

• Site of the primary tumor
• Tumor size and number of tumors
• Lymph node involvement (spread of cancer into lymph nodes)
• Cell type and tumor grade (how closely the cancer cells resemble normal tissue cells)
• The presence or absence of metastasis

Many cancer registries, such as NCI’s Surveillance, Epidemiology, and End Results Program (SEER), use summary staging. This system is used for all types of cancer. It groups cancer cases into five main categories:

Ø  In situ

Abnormal cells are present only in the layer of cells in which they developed.

Ø  Localized

Cancer is limited to the organ in which it began without evidence of spread.

Ø  Regional

Cancer has spread beyond the primary site to nearby lymph nodes or organs and tissues.

Ø  Distant

Cancer has spread from the primary site to distant organs or distant lymph nodes.

Ø  Unknown

There is not enough information to determine the stage.

The types of tests used for staging depend on the type of cancer. Tests include the following:

ü  Physical exams are used to gather information about the cancer. The doctor examines the body by looking, feeling, and listening for anything unusual. The physical exam may show the location and size of the tumor(s) and the spread of the cancer to the lymph nodes and/or to other organs.

ü  Imaging studies produce pictures of areas inside the body. These studies are important tools in determining stage. Procedures such as x-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and positron emission tomography (PET) scans can show the location of the cancer, the size of the tumor, and whether the cancer has spread.

ü  Laboratory tests are studies of blood, urine, other fluids, and tissues taken from the body. For example, tests for liver function and tumor markers (substances sometimes found in increased amounts if cancer is present) can provide information about the cancer.

ü  Pathology reports may include information about the size of the tumor, the growth of the tumor into other tissues and organs, the type of cancer cells, and the grade of the tumor. A biopsy may be performed to provide information for the pathology report. Cytology reports also describe findings from the examination of cells in body fluids.

ü  Surgical reports tell what is found during surgery. These reports describe the size and appearance of the tumor and often include observations about lymph nodes and nearby organs.

Sign and Symptoms

Generally, cancer symptoms can be divided into three categories:

      Local symptoms

They are restricted to the site of primary cancer. They can include hemorrhage (bleeding from the skin, mouth or anus), lumps or swelling (tumor), ulceration and pain. Even though local pain commonly occurs in advanced cancer, the initial swelling is always painless.

      Metastatic symptoms

They are due to the spread of cancer to other sites in the body. They can include enlarged lymph nodes which can be felt or sometimes seen under the skin, hepatomegaly (enlarged liver) or splenomegaly (enlarged spleen) which can be felt in the abdomen, neurological symptoms, and pain or fracture of affected bones.

      Systemic symptoms

They occur due to distant effects of the cancer that are not related to metastatic or direct spread. Some of these effects can include weight loss (poor appetite and cachexia), excessive sweating (especially night sweats), fatigue, anemia (low red blood cell count) and other specific conditions termed paraneoplastic phenomena. These may be mediated by hormonal or immunological signals from the cancer cells. 

Causes

Most people don’t realize that cancer is actually preventable in many cases. It is undoubted that learning what causes cancer and what the risk factors are is the first step in cancer prevention. Many cancer risk factors can be prevented, thus reducing the likelihood of developing cancer.

• Chemical substances such as carcinogens contain in tobacco smoke
• High salt diet and lack of exercise
• Virus, bacteria and parasites infection

             For example:

             Virus      : Human Papiloomavirus

             Bacteria  : Helicobacter

             Parasites : Schistosoma heamatobium

• Ionising and non-ionising radiation
• Heredity