What Is Cancer

Cancer is a group of diseases resulting from abnormal cells that divide uncontrollably in the body. There are more than 100 types of cancer. In advanced cases, cancer cells often invade other tissues and metastasize, or spread to other regions of the body. When cancer develops, it is crucial for doctors and patients to be vigilant in observing and identifying symptoms which may indicate cancer. Cancer testing is also a critical part of the cancer diagnosis and treatment process. The sooner cancer is properly diagnosed and treated, the greater the patient’s chance of a full cure.

Cancer Categories

Cancer is often categorized into five major types: carcinoma, sarcoma, leukemia, lymphoma, and myeloma. Cancers of the central nervous system may also be considered a fifth category. Central nervous system cancers begin in the tissues and cells of the spinal cord and brain, which comprise the central nervous system.


Carcinoma is a category of cancer that originates in epithelial tissue, or tissue which lines the outer or inner surfaces of the body. These tissues include the skin, as well as the tissues that cover or line the internal organs. Carcinoma is the most common category of cancer.


Sarcoma begins in cartilage, cone, muscle, fat, blood vessels, or other supportive or connective tissue in the body. Sarcoma is a rare category of cancer, as the vast majority of cancers are carcinomas. It is estimated that 60 percent of sarcoma of the soft tissue develops in the patient’s leg or arm.


Leukemia is a cancer category wherein the cancer begins in blood-forming tissue, including bone marrow. Bone marrow is the soft tissue located within most bones of the body. As a result, large quantities of abnormal blood cells are manufactured and released into the patient’s blood stream.

Lymphoma and Myeloma

Lymphoma and myeloma affect the white blood cells of the immune system. White blood cells help to protect from disease and infection by fighting foreign bodies. Lymphoma is a type of blood cancer that develops in the lymphocytes, a type of white blood cells. Myeloma begins in bone marrow and affects plasma cells, another type of white blood cell that produces infection-fighting antibodies.

Cancer Symptoms

Cancer symptoms vary depending on several factors, such as the type of cancer, stage, location, and current health of the patient. Many forms of cancer do not exhibit noticeable symptoms until they reach more advanced stages. Unfortunately, this often equates to greater difficulty in treating the cancer. For this reason, it is crucial for all individuals to be alert and aware of changes that occur in their bodies. In many cases, the symptoms a patient experiences may be the only indicator of the cancer. In general, cancer symptoms may include bodily pain, fever, unexplained weight loss, and changes in the skin.

The following types of cancer may exhibit the following symptoms:

  • Colorectal cancer symptoms may include bowel habit changes, diarrhea, constipation, rectal bleeding, and persistent abdominal pain.
  • Breast cancer symptoms may include a lump or thickening of breast tissue, inverted nipple, bloody nipple discharge, and changes in breast shape and size.
  • Prostate cancer symptoms may include difficulty urinating, bloody urine or semen, pelvic discomfort, and erectile dysfunction.
  • Lung cancer symptoms may include a persistent cough, shortness of breath, chest pain, wheezing, hoarseness, bone pain, and headache.


Cancer Testing and Diagnosis

Cancer testing and diagnosis are hand-in-hand, as cancer testing is critical for proper cancer diagnosis. Additionally, cancer testing is also used to create a personalized treatment plan after a cancer diagnosis is made. The type of cancer testing administered will depend on several factors, such as the type of cancer suspected and the nature of the symptoms the patient is experiencing.

Cancer testing may be administered through tests such as:

  • Imaging tests. These create pictures of the patient’s internal structures. Imaging tests include X-rays, computerized tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), bone scans, and ultrasounds.
  • Laboratory tests. Lab tests involve a sample such as blood, urine, or tissues, which is collected and sent to a specialized lab for examination. Laboratory testing includes complete blood count (CBC), urine cytology, blood protein tests, and tumor marker testing.
  • Endoscopic tests. Endoscopy involves the insertion of a tube instrument with an attached camera. Endoscopic tests allow the physician to examine certain organs and systems, such as the gastrointestinal tract.




Allen, Liz, et al. “Cancer.” Nature 411.6835 (2001): 335. Academic OneFile. Web. 15 Nov. 2013.

“Knowing lung cancer symptoms could improve survival.” AORN Journal Jan. 2003: 15. Academic OneFile. Web. 15 Nov. 2013.

Kolata, Gina. “How Bright Promise in Cancer Testing Fell Apart.” New York Times 8 July 2011: A1(L). Academic OneFile. Web. 15 Nov. 2013.