Introduction to Cancer
Cancer is a disease characterized by the uncontrolled growth of cells in the body. These cells grow abnormally and do not die. Normal cells in the body follow an orderly path of growth, division, and death. Unlike regular cells, cancer cells do not experience the programmed death and instead continue to grow and divide. This leads to a mass of tissue or lump of abnormal cells called as Tumor.
A tumor can be:

  1. Benign Tumor
    Benign tumors are not cancerous, i.e. they are a mild and non-progressive. They are typically surrounded by an outer surface that inhibits their ability to become cancerous. Hence, they are usually harmless to human health and can be removed by surgery. However, many types of benign tumors have the potential to become cancerous.
  1. Malignant Tumor
    Malignant Tumors are cancerous. Cells from malignant tumors can invade nearby tissues and can also break away and spread to other parts of the body.

Although the exact cause of many cancers remains unknown, there are various factors which may trigger the occurrence of cancer. These factors include:

  • Tobacco
  • Drinking excess alcohol
  • Unhealthy lifestyle & diet
  • Obesity
  • Infections
  • Radiation
  • Lack of physical activity
  • Environmental pollutants
  • Excessive sunlight exposure
  • Genetic problems

Types of Cancer
Cancers are classified by the type of cell that the tumor resembles and is therefore presumed to be the origin of the tumor. These types include:

  1. Carcinoma
    Cancer that begins in the skin or in tissues that cover internal and external parts of the body such as lung, breast, prostate and colon cancer
  1. Sarcoma
    Cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue
  1. 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
  1. Lymphoma and myeloma
    Cancers that begin in the in the lymph nodes and immune system tissues
  1. Adenomas
    Cancers that arise in the thyroid, the pituitary gland, the adrenal gland, and other glandular tissues.
  1. Central nervous system cancers
    Cancers that begin in the tissues of the brain and spinal cord

Signs / Symptoms of Cancer
Symptoms of cancer depend on the type and location of the cancer. For example, lung cancer can cause coughing, shortness of breath, or chest pain. Colon cancer often causes diarrhea, constipation, and blood in the stool. Some cancers may not have any symptoms at all. In certain cancers, such as pancreatic cancer, symptoms often do not start until the disease has reached an advanced stage.
The following symptoms can occur with most cancers:

  • Chills
  • Fatigue
  • Fever
  • Loss of appetite
  • Malaise
  • Night sweats
  • Weight loss
  • Lumps or swelling (tumor), 
  • Hemorrhage (bleeding from the skin, mouth or anus)
  • Ulceration and pain

Although local pain commonly occurs in advanced cancer, the initial swelling is often painless. None of these are diagnostic, as many of these symptoms commonly occur in persons who do not have cancer. Benign tumors are very diverse, and may be asymptomatic or may cause specific symptoms depending on their location and tissue type. Symptoms or pathological effects of some benign tumors may include:

  • Bleeding or occult blood loss causing anemia
  • Pressure causing pain or dysfunction
  • Physical changes on body
  • Itching
  • 'Hormonal syndromes' resulting from hormones secreted by the tumor
  • Obstruction, e.g., of the intestines
  • Compression of blood vessels or vital organs

Related Tests to Cancer
Common tests include the following:

  • Biopsy of the tumor
  • Blood tests (which look for chemicals such as tumor markers)
  • Bone marrow biopsy (for lymphoma or leukemia)
  • Chest x-ray
  • Complete blood count (CBC)
  • CT scan
  • MRI scan
  • Endoscopy

Synonyms for Cancer
Canker disease, Carcinoma, malignancy, tumor, malignant neoplastic disease, malignant tumor, malignant neoplasm, metastatic tumor