Are We Really Born With Cancer Cells?

For all the threats that cancer poses, the truth is that most of us know more about 1970s sitcoms than we really know about cancer. For instance, you probably don't know that you have cancer. That's right.

Every single person has cancer cells in them. But in most cases, your body finds the cells, realizes that they're foreign, and kills them right away without you even knowing that it happened.

Our bodies have the ability to get rid of these cells most of the time. When our bodies do not recognize the cell as a cancer or can't kill it, then it can become a cancer.

Family Cancer Syndromes

Cancer is such a common disease that it is no surprise that many families have at least a few members who have had cancer.

Sometimes, certain types of cancer seem to run in some families. Sometimes, this is because family members have certain risk factors in common, such as smoking, which can cause many types of cancer. It can also be due in part to other factors, like obesity, that tend to run in families and influence cancer risk.

But in some cases the cancer is caused by an abnormal gene that is being passed along from generation to generation.

Although this is often referred to as inherited cancer, what is inherited is the abnormal gene that can lead to cancer, not the cancer itself. Only about 5% to 10% of all cancers result directly from gene defects (called mutations) inherited from a parent. This document focuses on those cancers.

Every cell in your body has all of the genes you were born with.

Although all cells have the same genes and chromosomes, different cells (or types of cells) may use different genes. For example, muscle cells use a different set of genes than skin cells use. The genes that the cell doesn't need are turned off and not used. The genes that the cell is using are activated or turned on.

Family cancer syndromes - when should I worry?
When many cases of cancer occur in a family, it is most often due to chance or because family members have been exposed to a common toxin, such as cigarette smoking. Less often, these cancers may be caused by an inherited gene mutation causing a family cancer syndrome.

Certain things make it more likely cancers in a family are caused by a family cancer syndrome, 
such as:
  • Many cases of an uncommon or rare type of cancer (like kidney cancer).
  • Cancers occurring at younger ages than usual (like colon cancer in a 20 year old)
  • More than one type of cancer in a single person (like a woman with both breast and ovarian cancer)
  • Cancers occurring in both of a pair of organs (both eyes, both kidneys, both breasts)
  • More than one childhood cancer in a set of siblings (like sarcoma in both a brother and a sister)
  • Cancer occurring in the sex not usually affected (like breast cancer in a man)
Before you decide that cancer runs in your family, first gather some information. For each case of cancer, look at:
  • Who is affected? How are we related?
  • What type of cancer is it? Is it rare?
  • How old was this relative when they were diagnosed?
  • Did this person get more than one type of cancer?
  • Did they smoke or have other known risk factors?
Cancer in a close relative, like a parent or sibling (brother or sister), is more cause for concern than cancer in a more distant relative. Even if the cancer was from a gene mutation, the chance of it passing on to you gets lower with more distant relatives.

It is also important to look at each side of the family separately.

Having 2 relatives with cancer is more concerning if the people are related to each other (meaning that they are both on the same side of the family). For example, if both relatives are your mother's brothers it means more than if one was your father's brother and the other was your mother's brother.

The type of cancer matters, too. More than one case of the same rare cancer is more worrisome than cases of a more common cancer. For some very rare cancers, like cancer of the adrenal cortex, the risk of a certain family cancer syndrome is relatively high with even one case.

Having the same type of cancer in many relatives is more concerning than if it is several different kinds of cancer. Still, in some family cancer syndromes, a few types of cancer seem to go together.

For example, breast cancer and ovarian cancer run together in families with hereditary breast and ovarian cancer syndrome (HBOC). Colon and endometrial cancers tend to go together in a syndrome called hereditary non-polyposis colorectal cancer (HNPCC), also known as Lynch syndrome.

The age of the person when the cancer was diagnosed is also important. For example, colon cancer is rare in people under 30. Having 2 or more cases in close relatives under 30 could be a sign of an inherited cancer syndrome.

 On the other hand, prostate cancer is very common in elderly men, so if both your father and his brother were found to have prostate cancer when they were in their 80s, it is less likely to be due to an inherited gene change.

Certain kinds of benign (not cancer) tumors and medical conditions are sometimes also part of a family cancer syndrome.

For example, people with the multiple endocrine neoplasia, type II syndrome (MEN II), have a high risk of a certain kind of thyroid cancer.

They also often have hyperparathyroidism (overactive parathyroid glands) and may develop adenomas (benign tumors) of the parathyroid glands and can also can get tumors in the adrenal glands called pheochromocytomas, which are usually benign.

When many relatives have the same type of cancer it is important to notice if the cancer could be related to smoking. For example, lung cancer is commonly caused by smoking, so many cases of lung cancer in a family of heavy smokers is more likely to be due to smoking than to an inherited gene change.

Dr. Richardson-Heron’s cancer prevention tip to us is to avoid grilled and pan-fried meats. That includes all meats; beef, pork, chicken and fish! She explains that the high temperatures of frying and grilling meats, especially to the point of charring the flesh, breaks down the muscle and creates cancer causing chemicals.

The National Cancer Institute suggest ways to reduce our exposure to these cancer causing chemicals.
  • limit your consumption of red, processed and smoked meats
  • avoid direct exposure of all meats (beef, pork, chicken, and fish) to an open flame or a hot metal surface
  • avoid prolonged cooking times at high temperatures
  • use a microwave oven to pre-cook meat to reduce exposure time to high heat cooking such as pre-cook before grilling.
  • continuously turning meat over a high heat source compared to just leaving the meat on the heat source without flipping it often.
  • removing charred portions of meat and refraining from using gravy made from meat drippings

Genetic counseling and testing

People with a strong family history of cancer may want to find out about their genetic makeup. This knowledge may help the person or other family members in planning health care for the future. Since inherited mutations affect all cells of a person's body, they can often be identified by genetic testing that is done on blood samples.

Genetic counseling and testing may be recommended for some people with a strong family history of cancer.

American Cancer Society
We have some related information that may also be helpful to you. These materials may be viewed on our website or ordered from our toll-free number, 1-800-227-2345.

Along with the American Cancer Society, other sources of information and support include:

National Cancer Institute
Toll-free number: 1-800-4-CANCER (1-800-422-6237)

Provides accurate, up-to-date information on a variety of cancer-related topics such as finding support, financial assistance and other resources; coping with cancer; cancer genetics, etc (click the “Cancer Topics” tab on the home page). 

Also has an Online Cancer Genetics Services Directory to identify professionals who provide services related to cancer genetics (cancer risk assessment, genetic counseling, genetic susceptibility testing, and others). 


MedlinePlus. National Library of Medicine (US). Multiple endocrine neoplasia (MEN) II. 3/14/2012. Accessed at on 3/7/2014.

National Cancer Institute. Physician Data Query (PDQ). Cancer Genetics Overview. 2/18/2014. Accessed at on 3/7/2014

National Cancer Institute. Physician Data Query (PDQ). Genetics of Colorectal Cancer. 2/14/2014. Accessed at on 3/7/2014.