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Cancer Prevention: What You Need To Know

Heredity and Cancer

Why Is This a Problem?
Physically, each of us is organized as millions of microscopic units called cells. Our cells develop along different pathways to work together to form our many interacting organ systems. When we grow, repair or replace aging parts, our cells divide to form new cells. The program that directs all this is encoded in units called genes that are made of a material called DNA. Each cell has two copies of each gene. We inherit one copy of each gene from each of our parents. Every time a cell divides, all of its genes are copied and given to each new cell. Occasionally mistakes are made when the DNA is being copied and a cell inherits an altered copy of one or more genes. If that new cell divides, the mistake is copied. We call the mistake a mutation, and we call the altered gene a mutant gene. Eventually we can end up with a large collection of cells that have many mutant genes. Depending on what the mutations are, the cells may still be normal, or they may be abnormal and then behave abnormally. If an abnormal gene is passed on to a person’s child, then that child has an inherited abnormality.

In order for us to remain healthy, our cells have to function in a controlled fashion. When a gene becomes abnormal, it may upset the balance of the cell. If the cell is pushed out of control so that it divides when it should not and spreads to where it does not belong, it has become malignant. When a malignant cell divides, it makes more malignant cells. If these malignant cells divide faster than the rest of the body can get rid of them, then they form a growing cancer that makes the person sick. Our cells have many genes that provide back up controls so that we have to accumulate several predisposing mutations before we develop a malignant cell. Our tissues and organ systems also form many barriers that block the spread of malignant cells and destroy them before they can make us ill. That means that very few people actually inherit full blown cancer but some of us may inherit a set of genes that makes us more likely than others to develop certain kinds of cancer.

When we review family histories and find high rates of specific cancers that raise the possibility of a hereditary cancer syndrome, we can try to develop cancer screening programs for those families in order to find their cancers early enough to cure them. As we learn more about those cancers, we can also try to develop cancer prevention measures. In addition, we try to identify the genes and the defects that predispose members of families to those cancers. This helps us learn what causes these cancers and leads us to new treatments.

What Can I Do to Prevent the Problem?
Many of us may have a moderate predisposition to cancer that makes certain things more dangerous for us than for others. For instance, some cancers are caused in part by things we do such as smoking or chewing tobacco, or drinking alcohol. We should all avoid these habits. Individuals who know they may be predisposed toward certain cancers (those with parents, brothers or sisters, or children with certain cancers) should check the section on early detection of cancer for screening guidelines.

Where Can I Get More Information?

University of Iowa Resources
The Holden Cancer Center offers a Familial Cancer Consultation Clinic. In this clinic, physicians and genetic counselors assess family and individual risks of developing cancer. The physicians can then give recommendations on screening and preventive measures based on that risk assessment. The multidisciplinary team can also provide support services, follow-up and referrals that individuals who have a high risk of developing cancer may also need.

• University of Iowa Health Care, Department of Medical Genetics
• Cancer Information Service (1-800-237-1225)

Other Resources

• National Cancer Institute
  http://www.cancer.gov/cancer_information/
• Hereditary Cancer Institute
  http://medicine.creighton.edu/medschool/PrevMed/hc.html
• National Familial Pancreas Tumor Registry at Johns Hopkins Hospital
  http://pathology.jhu.edu/PANCREAS_NFPTR

Additional Information

• Hereditary Diseases and Cancer
• Definition of Terms

If you would like more information about heredity and cancer or to obtain phone numbers to the above organizations, please contact the Cancer Information Service at (1-800-237-1225) or e-mail: cancer-information@uiowa.edu.

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