Cancer Overview

Cancer at a glance

  • Cancer is a group of related diseases caused by uncontrolled cell growth.
  • There are over 100 types of cancer including the four most common: breast, colorectal, lung and prostate.
  • Treatments vary but the most common are chemotherapy, radiation therapy and surgery.
  • Cancer treatment and detection are becoming more advanced resulting in fewer deaths.
  • Many cancers can be prevented through healthy lifestyle choices and avoiding known risk factors.

What is cancer?

According to the American Cancer Society (ACS), there are roughly 15.5 million people with a history of cancer living in the United States currently. While cancer is the second most common cause of death in the U.S, more people are living full lives after treatment than ever before.

Cancer is a term used to describe a group of related diseases. There any many types but what they all have in common is the uncontrolled growth and division of cells. This can occur rapidly or at a slower rate depending on the type of cancer.

Typically, the cells grow, divide and die as the body needs them. Cancer disrupts this process, causing damaged cells to survive rather than die, and new cells to form needlessly. The creation of these extra cells may develop growths called tumors.


Cancer terminology can get confusing. While the ACS has an exhaustive list of all terms, below are the basic terms to help navigate the disease.

  • Benign: Not cancerous.
  • Benign tumor: Noncancerous abnormal growth of cells that creates a lump or mass of tissue but will not spread to other areas of the body.
  • Biopsy: Removal of a sample of tissue to determine if cancer cells are present.
  • Carcinogen: A substance that helps or causes cancer to grow.
  • Malignant: Cancerous.
  • Malignant tumor: A mass of cancer cells that could spread into nearby tissue.
  • Metastasis/Metastasize: The cancer cells have spread into one or more sites within the body.
  • Oncology: The field of medicine focused on the diagnosis and treatment of cancer.
  • Remission: When the signs or symptoms of the disease are no longer present.
  • Stage: The extent of the cancer’s growth, usually assigned numerically from I to IV.

Causes of cancer

There are many causes of the disease, some of which are not preventable while others are. The World Health Organization estimates that 30-50 percent of all forms of the condition could be prevented (see Cancer prevention below).

This disease can be caused by family genetics, exposure to sunlight or behaviors. There’s usually no way to know for certain why one person gets cancer and another person doesn’t. When several studies link a health or behavioral factor to people who develop the disease, oncology scientists consider it a risk factor.

Currently, the largest risk factor for unpreventable cancers is age. Eighty-seven percent of all cancers in the U.S are diagnosed in individuals 50 years of age or older.

Risk factors

Following are some of the most probable risk factors identified through study.

  • The age of the person.
  • Person’s diet.
  • Hormone problems.
  • Level of alcohol consumption.
  • Tobacco use.
  • Exposure to substances that cause the disease, infectious agents, sunlight or radiation.
  • Immunosuppression issues.
  • Chronic inflammation.


For many types of cancer, if a person has a family history of the disease it is more likely that he or she will eventually develop it as well. This is thought to be the result of an inherited genetic variation.

Additionally, the National Cancer Institute (NCI) identifies three main types of genes that could contribute to, or drive, growth.

  • Proto-oncogenes: These genes are involved in typical cell growth and division but can sometimes be altered, developing into cancer-causing genes.
  • Tumor suppressor genes: These cells also help control cell division and growth. If these cells are altered, they may uncontrollably divide.
  • DNA repair genes: Involved in fixing damaged DNA, mutations in the cells may cause additional mutation in other genes. These mutations together may be the reason why some cells become cancerous.
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Cancer prevention

The best way a person can prevent cancer is to adopt a lifestyle that does not involve the risk factors listed above, like smoking and maintaining a healthy weight. Of course, people can’t control their age or genetics, but avoiding known risk factors can reduce the chances of getting some types of the disease.

Certain cancers that are caused by infections can be prevented through vaccination, behavioral changes and treatment of the initial infection. These cancer-causing infections include human papillomavirus (HPV), hepatitis B virus (HBV), hepatitis C virus (HCV) and more.

There are more than 5 million cases of skin cancer diagnosed annually, many of which could be prevented with proper skin protection and avoiding tanning devices.

Additionally, screenings can prevent the spread of pre-cancerous cells and allow for early detection, which means treatment would be more effective.

Types of the disease

There are over 100 different types of cancer. Often, it is named for the tissue or organs where it began, such as lung cancer that begins in the lungs, and so on. The most common type of cancer in the U.S. is breast, followed by lung and prostate cancer.

Cancer is often categorized by the type of cells.

  • Carcinoma is the most common type, which is formed by the cells that cover the inside and outside of the body, known as epithelial cells.
  • Leukemia begins in bone marrow, where the tissue is blood-forming. Leukemia does not become a tumor but builds up abnormal white blood cells in the blood and bone marrow. This crowds out the number of normal blood cells making it difficult to fight infection, control bleeding or transport oxygen to tissue.
  • Lymphoma begins in the disease-fighting white blood cells, which are a part of the immune system. These abnormal cells build up in the lymph nodes.
  • Melanoma starts in the specialized cells that make melanin, which gives the skin color. Most of these cancers form on the skin, but melanomas can also develop in other tissues that are pigmented, such as the eyes.
  • Sarcoma causes the malady to form in the bone and soft tissue, including fat, blood vessels, fibrous tissue and muscle.
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Diagnosis and treatment

There are a variety of ways a physician may diagnose these conditions including a physical exam, laboratory testing of blood, urine tests, imaging scans such as CT scans and MRIs, or a biopsy of a tumor.

If this testing determines that a person does have the disease, there will be more thorough testing to identify what stage it is in. This helps the oncologist determine the best course of treatment.

Treatment options often depend on what type and stage the cancer is. The goal of treatment is to remove or destroy the cancerous cells. The three most common forms of treatment are chemotherapy, radiation and surgery.

  • Chemotherapy distributes into the patient chemicals designed to attack the cancerous cells.
  • Radiation therapy uses high doses of radio energy to kill cancer cells and shrink tumors.
  • Surgery involves performing an operation to treat cancerous cells and tissue by physically removing the affected cells and nearby tissue from the body.

Living with cancer

Treatment and diagnosis tools continue to improve and result in more people living after they have the disease. According to an NCI study, there are more than 2.3 million fewer cancer deaths from 1991 to 2015.

Treatments can have differing and uncomfortable side effects on the body. It is important to maintain good health through a nutritious diet, staying mildly active, getting plenty of rest and generally keeping health and wellness a top priority.