Colon Cancer, The Genetic Factor

Medical Author: Dennis Lee, MD
Medical Editor: Jay W. Marks, MD, and Barbara K. Hecht, Ph.D.

Introduction

Colon cancer is the fourth most common cancer in the United States. In the US an estimated 130,000 men and women will develop colon cancer and more than 50,000 will die from it each year. The life-time risk for individuals to develop colon cancer is approximately 6%, but the risk increases to 18% among individuals who have a first degree relative (parent, sibling or child) with colon cancer.

What causes colon cancer?

Mutant genes cause colon cancer. The human body is composed of trillions of cells. Inside each cell are two sets of 23 chromosomes, one set from each parent. Each chromosome contains long strands of DNA. The DNA encodes thousands of genes. The genes carry the genetic information that is passed down from both parents. Different genes are responsible for different structures and functions in the body. For example, some genes influence eye color, hair color, height, and other physical characteristics. Other genes regulate cell growth and division. Still other genes prevent cells from invading neighboring tissues or spreading to distant organs.