Hereditary Cancers

Most cancers are sporadic, meaning that cancer strikes any given person at any given time and is not linked to heredity genes. However research has shown that there about 10% of all cancers have a hereditary component. The best place to start in finding out if you are at risk for hereditary cancer is to complete the family history cancer risk checklists.


Breast and Ovarian Cancer

Breast cancer is one the most common forms of cancer for women effecting approximately 7% of women in the United States. Although ovarian cancer is much less common, effecting approximately 2% of women in the United States, it is of greater concern as many times ovarian cancer goes undetected until it has reached advanced stages of the disease. Although most cases of breast and ovarian cancer is sporadic, about 10% may be due to a hereditary predisposition.

It is well know that breast and ovarian cancers often occur more frequently in women whose relatives have also had these diseases. This Cancer Risk Checklist will help you determine if you might be at risk. We now know that many cases of inherited breast and ovarian cancer are due to inherited genetic mutation. The genes responsible for ovarian cancer are BRCA1 and BRCA2 located in chromosome 17 and 13 respectively. These are tumor suppressor genes, it is only when a mutation is present in these genes that they are unable to prevent cancer. Women with these genetic mutations are at much greater risk for developing breast and ovarian cancer. Therefore, a person who inherits a mutated gene has a greatly increased risk of cancer, "cancer-prone", and more likely to develop cancer at a younger age or to have multiple cancers.

As a matter of fact, women with inherited gene mutations in BRCA1 or BRCA2 have an elevated risk for developing breast cancer by age 70 of 87% and before age 50 to between 33% - 50%. The elevated risk for developing ovarian cancer before age 70 is between 28% and 44%.

  • By age 50, between 33% and 50% of all women with a BRCA mutation will develop breast cancer, versus 7% risk for the general population


  • Women with a BRCA Mutation have a 27% to 44% lifetime risk of developing ovarian cancer, versus a less than 2% risk for the general population


  • Women with a BRCA mutation who have already had breast cancer have up to a 20% risk of developing cancer in the other breast within five years of their first diagnosis


    • Knowing your cancer risk may help you and your physician make better-informed decisions about surveillance and early detection or treatment of these inherited cancers. Monthly breast self-examination is one of best forms of early breast cancer detection, other recommended early cancer detection techniques should include annual mammography, pelvic examination, transvaginal ultrasound of the ovaries and a blood test to measure a marker of ovarian cancer called CA-125.

    All cancer is genetic because it results from mutations in genes, however most cancerous mutations are random events, which are not passed on to offspring. Nonhereditary or sporadic cancer results from these random mutations.

    Visit our Breast Health Center and the Women' s Health Resource Center for more information on programs and services available at California Pacific Medical Center. Cancer Risk Checklist for Breast and Ovarian Cancer

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    Colon and Endometrial Cancer

    Among all cancers, colorectal cancer is the second leading cause of cancer-related deaths among Americans and endometrial cancer, also known as uterine cancer, is the fourth most common cancer in women. The two most important genes responsible for the hereditary risk of colon and endometrial cancer are MLH1 and MSH2, chromosome 3 and 2 respectively. These are tumor suppressor genes, it is only when a mutation is present in these genes that they are unable to prevent cancer. Colorectal cancer is one the most common kinds of cancer and each year more than 130,000 individuals will be diagnosed with colon or rectal cancer. Most colorectal cancer is sporadic, however 5% is caused by inherited genetic mutations called Hereditary Nonpolyposis Colorectal Cancer (HNPCC) syndrome. Endometrial cancer, also associated with HNPCC syndrome, is the most common gynecologic malignancy, making up approximately 95% of all uterine cancers diagnosed.

    Reviewing the Cancer Risk Checklistfor colorectal and endometrial cancer is one of the most important ways of determining whether an individual may be at risk for HNPCC syndrome. Without medical intervention approximately 25% of persons with the inherited genetic mutations will develop colorectal cancer by age 50 and approximately 80% by age 70. Women with HNPCC have a greatly elevated risk of developing endometrial cancer, approximately 20%, by age 50 and approximately 60% by age 70.

  • By age 70, it is estimated that 80% of persons with an HNPCC gene mutation will develop colorectal cancer, versus 2% risk for the general population


  • By age 70, it is estimated that 60% of women with an HNPCC gene mutation will develop endometrial cancer, versus 1.5%


    • Knowing your cancer risk may help you and your physician make better-informed decisions about surveillance and early detection or treatment of these inherited cancers. The usual surveillance for colon cancer is comprised of a colonoscopy every 1-3 years and for endometrial cancer annual transvaginal ultrasound and or endometrial aspiration. Other preventive measures should be discussed with your healthcare professional.

    All cancer is genetic because it results from mutations in genes, however most cancerous mutations are random events, which are not passed on to offspring. Nonhereditary or sporadic cancer results from these random mutations.

    Visit the Women' s Health Resource Center for more information on programs and services available at California Pacific Medical Center.
    Cancer Risk Checklist for Colon and Endometrial Cancer

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    What is Genetic Testing?

    Genetic testing examines a person's DNA for a gene change that can cause or predispose us for a disease or disorder. DNA is housed within chromosomes that are located in the nucleus of our cells. Chromosomes are bundles of genetic information that determine our physical features. The majority of cells in the human body have 46 chromosomes that come in 23 pairs, one inherited from the father and one inherited from the mother. Genes are located on these chromosomes. Individuals with a parent who has a genetic mutation has a 50% chance of inheriting that gene, therefore it is important to understand that not all individuals from a high-risk family are at the same risk of inheriting genetic mutations.

    Through a blood or tissue sample, the DNA in cells is examined for gene changes or mutations. Even if a patient is shown to have a DNA mutation for these genetically linked cancers it does not mean that the patient will develop cancer, this means only that the patient may have a propensity toward developing one of these cancers and that the gene may be passed down to their children.
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