Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at December 9, 2015

Cancer refers to a collection of related illnesses. While cancer may occur anywhere in the body, all forms of cancer begin when abnormal cells divide uncontrollably into a mass called a tumor. One in three people will be affected by cancer at some point in their life.


Definition & Facts

There are more than 200 types of cancer although all occur when cells become abnormal and grow out of control. Cancer can begin anywhere in the body when damaged or old cells survive and begin to grow out of control rather than dying.

These abnormal cells begin to grow and produce new cells that aren't necessary and these extra cells then continue growing into a mass called a tumor. While many types of cancer form a solid tumor, there are also forms of cancer like leukemia that do not form a solid mass.

Because these cancerous masses are malignant, abnormal cells may break off and travel through the blood stream or lymph system to form new tumors in new areas of the body.

Symptoms & Complaints

The symptoms of cancer range a great deal and some people do not have symptoms at all. Cancer symptoms depend largely on where the cancer develops, the size of the tumor, and how much it affected surrounding tissues and organs. Because there are more than 200 types of cancer, this group of diseases can result in virtually any symptom or complaint. The following are common general symptoms of cancer:

  • Fatigue that doesn't improve with rest. It can occur early in cancers like leukemia or as other cancers spread.
  • Fever is a common sign of cancer that often means the cancer has spread. Virtually all people with cancer develop a fever at some point.


Cancer is the result of mutations to the DNA inside of cells that cause errors in how the cells functions. While some of these gene mutations are inherited, these mutations account for a very small percentage of cancers.

There are hundreds of causes of gene mutations after birth. There are many possible causes of cancer including genetic factors, some infections, environmental exposures to chemicals, and lifestyle factors. Some factors are known carcinogens (capable of causing cancer) that lead to specific types of cancer.

Smoking cigarettes, for example, introduces more than 60 well-known carcinogens that can lead to lung cancer. Other substances that have been shown to cause cancer include UV radiation (from tanning beds and sunlight), alcoholic beverages, wood dust, outdoor air polution, talcum powder, drugs that suppress the immune system, and hormone therapy.

Diagnosis & Tests

There are dozens of tests and diagnostic tools to diagnose cancer. If cancer is suspected, a doctor may order blood tests or lab tests such as an analysis of a patient's urine or a biopsy of a suspicious lump or mole. A complete blood count (CBC) is a common test that measures the amounts of types of blood cells in the blood.

This test can be used to detect blood cancers, which can be confirmed with a bone marrow biopsy. A blood protein test can be used to examine proteins in the blood to look for abnormal immune system proteins that may be elevated. A tumor marker test is test that checks for tumor markers, or chemicals produced by tumor cells that can be detected in the blood.

This test can be used to look for prostate-specific antigen (PSA) for prostate cancer, cancer antigen 125 for ovarian cancer, and calcitonin for thyroid cancer. Screening tests may also be used to detect cancer early. Examples of common cancer screening tests include a colonoscopy for colorectal cancer, mammography for breast cancer, and pap tests for cervical cancer.

Treatment & Therapy

Most people diagnosed with cancer receive a combination of treatment options. The types of treatments available depend on the type of cancer and how far it has spread. Surgery ay be used to diagnose and treat many forms of cancer. Surgery has the greatest chance of curing cancer if the cancer has not spread.

Chemotherapy is another common form of treatment that uses drugs to kill tumor cells. Radiation therapy uses high-energy waves to damage cancer cells. It's one of the most common types of cancer treatment and may be combined with other treatment options. There are also several new forms of therapy that are still being explored.

Targeted therapy is a new form of treatment that uses drugs to attack cancer cells directly without damaging healthy cells like chemotherapy. Immunotherapy uses the body's immune system to target abnormal cancer cells. Some forms of cancer also respond to hormone therapy to stop the spread of cancer cells or stem cell transplants to replace blood-forming stem cells lost during treatment.

Prevention & Prophylaxis

The easiest way to reduce the risk of cancer is adopting lifestyle changes. Avoiding tobacco is an important aspect of cancer prevention that reduces the risk of lung, mouth, and throat cancer. A healthy diet high in protein, fruits, and vegetables can reduce the risk of stomach, colon, and rectal cancer.

Limit alcoholic drinks to reduce the risk of breast, lung, colon, kidney, and liver damage. Maintaining a healthy weight and remaining physically active reduces the risk of prostate, breast, colon, kidney, and lung cancer. Wearing sunscreen daily, avoiding tanning beds, and staying in the shade can reduce the risk of skin cancer, one of the most common and preventable forms of cancer.

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