What is Cancer?

Considering cancer from a technical viewpoint, it is just another natural process in which cells divide and grow at a rapid rate. It’s an abnormal process that destroys tissue, but that doesn’t change the fact that it’s a biological process. Yet the word cancer strikes fear in people’s hearts and for good reason. Over 560,000 people die of many different types of cancer in the United States alone each year.1

What exactly is cancer? What triggers the erratic cell division and growth? How does it cause pain and eventual death if not treated?

One of the best ways to confront fears about anything is to learn more about it. One of the first things you will learn is that cancer is curable if it’s detected early enough. That is true for almost all types of cancer. Unfortunately, not all cancer is detected early and that can complicate treatments. However, research is making remarkable strides in learning more about the biological mechanisms connected with cancer and in developing new treatment methods for all forms of cancer including breast cancer. Much of the most recent successes and advances have come from sophisticated technology that enables scientists to explore cancer cells on microscopic levels.

A Disease with Many Forms

Cancer comes in many forms. These include carcinoma which is a cancer of the inner or outer linings of the body (skin), sarcoma (bone, muscle, fat, cartilage or blood vessels), lymphoma and myeloma (immune system), leukemia (blood) and finally cancer of the central nervous system (brain and spinal cord). All of these cancer types have one thing in common – they start in the cells.

The human body is made up of trillions of cells so it is not surprising that there are over 100 cancer types. Cancer could potentially start in any cell in the body and be anywhere in the body.

Cells Behaving Well

To understand cancer, you have to understand how normal cells behave. Each cell has genes (DNA) responsible for controlling cell growth and division.  A normal cell is genetically programmed to divide in an orderly fashion. During division, DNA is copied or replicated, as one cell divides itself into two cells according to the instructions in its DNA. Cells even have instructions in their DNA to self-destruct and eventually, most cells die and their structures are recycled to make new cells in a process called apoptosis, or “programmed cell death”. This process is variable for different kinds of cells in the body and some, such as neurons (nerve cells) do not self-destruct for a very long time. Others, such as red blood cells, do so every four months. Certain genes have a regulatory role in controlling division. These genes include:2

  • Tumor suppressor genes – prevent abnormal division
  • Mismatch repair genes – repairs mistakes in DNA replication when cells divide, to prevent cancer formation
  • Oncogenes – genes that have the potential to form cancer when mutated

Chromosomes are strands of DNA and are stored in the nucleus of each cell. A gene is a segment of DNA that gives instructions for the production of a protein. These proteins have specific functions in cell behavior. When DNA replicates perfectly, cells divide normally and have normal behavior. But when certain genes are mutated causing abnormal division, signals to stop dividing are lost, and cancer is formed.

Cells Behaving Poorly

Simply stated, cancer is a cluster of cells with mutated DNA. When the DNA is mutated and cells continue to divide, abnormal cells are created and over time form a tumor. When tumor suppressor genes are mutated, they can no longer suppress abnormal cell division. When oncogenes are mutated, they permit disordered cell division. When mismatch repair genes are mutated, they stop “proofreading” and repairing the mistakes in DNA replication.

In all of these cases, uncontrolled cell growth is the result. The cells growing out of control form a cluster, or what we call a tumor. The process of a normal cell becoming a cancer cell involves several steps:3

  • A single mutation in DNA is either inherited or develops spontaneously
  • The cell is able to function normally with one mutation because each cell has two copies of each gene, one normal and one abnormal
  • The second copy of a gene is mutated and cells continue to divide out of control, causing a tumor
  • The tumor grows large enough to be detected and cancer can be diagnosed

Of course, this process does not happen overnight. Some cancers divide very slowly, taking years to become detectable while others divide, grow and spread quickly. Cancer cells continue to divide and tumors grow, recruiting their own blood supply in order to receive the necessary nutrients to continue dividing. The cells no longer have the ability to perform programmed cell death, so they continue to divide and outgrow their own blood supply. Because of that, the center portion of a tumor can be necrotic, or made of dead cancer cells.4

Tumors may continue to grow into and destroy healthy tissue, causing a number of symptoms. One of the most recognizable symptoms is pain, which unfortunately may be at later stages. Other symptoms include: 5

  • Mass formation
  • Hormones produced by the tumor, causing systemic symptoms
  • Bleeding
  • Organ dysfunction
  • Bone fractures at sites of tumors or metastasis
  • Blockage of ducts
  • Nerve compression

Finding a Way to Manage Mutations

Researchers are diligently working to find ways to detect genetic mutations and even support genetic repair with stem cells. Targeted drug therapies based on the unique characteristics of a patients cancer is the first step to improved treatment. There is still so much to learn, but the progress made thus far is simply remarkable.


1 Hartmann, Lynn C and Charles L. Loprinzi (2005) Mayo Clinic Guide to Women’s Cancers. New York: Mayo Clinic Health Information.

2 Ibid

3Defining Cancer (2011) Retrieve from National Cancer Institute at: www.cancer.gov/cancertopics/cancerlibrary/what-is-cancer

4 Murray Dr., M, ; Dr. Tim Birdsall; Dr. Joseph E. Pizzorno; Dr. Paul Reilly. (2002) How to Prevent and Treat Cancer with Natural Medicine. New York: Riverhead Books.

5 Cicala MD, Roger S. (2001) The Cancer Pain Sourcebook. Lincolnwood, Illinois: Contemporary Books.

This article was originally published on July 27,2012 and last revision and update of it was 9/2/2015.