What is cancer?

Cancer is a word no one wants to hear.

Cancer is something that oftentimes invokes bad memories, unpleasant thoughts, or worry. However, we must remember something about cancer: as unpleasant as it is to think about, it’s important that we understand what it is and why it affects people. By learning more about cancer, we can take care of others while simultaneously taking care of our own future health.


Where did the word cancer come from?1

cancerThe word cancer stems from the Greek word karkinos, which means “crab.” In around 400 B.C., Hippocrates was studying patients with end-stage cancer. Many historians disagree on the similarities he could have found between crabs and cancerous tumors—comparisons between both their hardness and stubbornness have been drawn, as well as with other similarities—but no matter what drew him to that comparison, he decided to call cancerous tumors karkinos

Several hundred years later, in around 47 A.D., Greco-Roman philosopher Celsus followed Hippocrate’s lead, listing cancerous tumors as cancer (the Latin word for crab) in his encyclopedia of medicine. Since then, the term cancer has become a universal term for any malignant cells within an organism’s body.

Similarly, the word oncologist stems from another Hippocratic term: the Greek onkos, which translates to “masses.”


On a physical level, what is cancer?2,3

lavender2According to the Mayo Clinic, “Cancer refers to any one of a large number of diseases characterized by the development of abnormal cells that divide uncontrollably and have the ability to infiltrate and destroy normal body tissue.” Most cancers come in the shape of cancerous tumors, while some, such as leukemia, do not always become tumors.

A malignant (cancerous) tumor is a cluster of cancerous cells. These cells can sometimes grow to destroy or damage the healthy cells and tissues surrounding them. In some instances, cells break away from malignant tumors and spread to different areas of the body, where they may form new tumors. This process is called metastasis. It’s important to note that having cancer does not automatically constitute metastasis.

black-star  Benign vs. Malignant: What’s the difference?

Benign tumors, unlike malignant tumors, are not cancerous

and do not spread to different parts of the body.

Rivaled only by heart disease, cancer is the second most common cause of death in the United States. However, survival rates are steadily increasing for many types of cancer, thanks to improvements in screening and treatment. For many, cancer is not a death sentence, but simply a difficult journey they must endure. ❖


How is cancer staged?4,5

Cancer is always staged on a scale from 0-4.4 Staging determines how much cancer there is in the body and how far it has spread. Although each diagnosis is different, cancers with the same stage tend to have the similar outlook and therefore receive similar treatments. Stages give doctors a good idea of how they will need to treat a patient’s cancer. The following chart from the National Cancer Institute5 gives a basic idea of what each stage of cancer means:

Stage What it means
Stage 0 Abnormal cells are present but have not spread to nearby tissue. Also called carcinoma in situ, or CIS. CIS is not cancer, but it may become cancer.
Stage I, Stage II, and Stage III Cancer is present. The higher the number, the larger the cancer tumor and the more it has spread into nearby tissues.
Stage IV The cancer has spread to distant parts of the body.

Doctors may use the following terminology to describe a patient’s cancer:

  • In situ— Abnormal cells are present and have not spread to neighboring tissue.
  • Localized— Cancer is limited to where it started and has not spread.
  • Regional— Cancer is now present in neighboring lymph nodes, organs, or tissues.
  • Distant— Cancer has spread to distant and unrelated parts of the body.
  • Unknown— Stage cannot be identified.

To learn more about stages, how they are selected, and what they mean, click here.




  1. Flatow, Ira. “Science Diction: The Origin Of The Word ‘Cancer.'” NPR. NPR, 22 Oct. 2010. Web. 19 Jul. 2016. (Link)
  2. “Cancer.” Mayo Clinic.  Mayo Foundation for Medical Education and Research, 23 May 2015. Web. 10 Jul. 2016. (Link)
  3. “What is cancer?” KidsHealth. The Nemours Foundation, 2016. Web. 13 Jul. 2016. (Link)
  4. “Cancer Staging.” American Cancer Society. American Cancer Society, Inc., 25 Mar. 2015. Web. 14 Jul. 2016. (Link)
  5. “Cancer Staging.” National Cancer Institute. National Institutes of Health, 9 Mar. 2015. Web. 14 Jul. 2016. (Link)
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