Cancer risk & hereditary cancer
Hereditary cancer is caused by changes in certain genes. Genes are the instructions that our bodies use to grow and function, and this information is passed down from parents to children. According to the American Cancer Society, an estimated 5 to 10 percent of cancer diagnoses are due to an inherited form of cancer. This means that 5 to 10 percent of people who receive a cancer diagnosis had a genetic factor that caused them to have a higher likelihood of developing the disease.
The most common hereditary cancers include:
- Breast cancer
- Ovarian cancer
- Uterine cancer
- Colon cancer
- Pancreatic cancer
Signs of hereditary cancer
If you or a close relative, such as a parent, child, brother, sister, aunt, uncle, niece, nephew, grandparent of grandchild, have any of the following risk factors, a referral to a genetic counseling clinic may be right for you.
Hereditary breast and ovarian cancer
- Invasive breast cancer or ductal carcinoma in situ (DCIS) diagnosed at or under age 50
- Two or more blood-related individuals with breast cancer
- Male breast cancer
- Ovarian, fallopian tube or primary peritoneal cancer at any age
- Breast cancer and one or more other separate cancers
- Breast cancer and large head circumference (57 cm or larger for women, 59 cm or larger for men) and/or mental retardation/autism
- Breast cancer with Eastern European Jewish ancestry, or Hispanic/Latino ancestry from Southern Colorado or northern New Mexico
Cancers that accompany breast cancer in inherited syndromes include a second, new breast cancer; brain, thyroid, pancreatic and endometrial cancers; lymphoma/leukemia; and adrenal cortical or choroid plexus carcinomas.
Hereditary colorectal cancer
- Colorectal OR uterine cancer diagnosed under age 60
- Two or more separate colorectal cancers in the same person
- Three or more blood-related individuals with colorectal or uterine cancer
- Colorectal cancer or uterine cancer and a personal or family history of other cancers
- Ten or more cumulative gastrointestinal adenomas or hyperplastic polyps
- Hamartomas (non-cancerous growths), juvenile polyps or Peutz-Jeghers polyps
- Pathology of the colorectal tumor shows microsatellite instability or evidence of a mismatch repair defect
Cancers/tumors that accompany colorectal cancer in inherited syndromes include uterine, ovarian, stomach, small intestine, pancreatic and urinary tract cancers, as well as brain tumors, sebaceous adenomas and keratoacanthomas.
Other hereditary cancer syndromes
- An identified inherited/genetic syndrome
- An individual with bilateral or multiple primary cancers or brain tumors
- An individual diagnosed with cancer at an unusually young age
- Three or more blood-related family members with the same type of cancer
- Rare cancers, such as medullary thyroid cancer, adrenocortical carcinoma, pheochromocytoma and paraganglioma
Genetic testing advances
Genetic testing for inherited cancer syndromes has advanced rapidly in the last few years. Expanded knowledge of genetics has also led to better insurance coverage and additional testing options that allow you to receive the testing needed to make informed choices about your health. Many former patients who pursued genetic testing previously have elected to undergo new testing that has provided new information. One such patient remarked after a cause of the cancer in her family was finally found, “My family has been looking for this explanation for 20 years.”
If you were seen for genetic counseling previously, even if you received normal test results, you may benefit from a follow-up appointment. If you declined genetic testing in the past because of cost, new options may allow you to receive testing at no or very little cost. If you already had genetic testing and the results were negative or uncertain, you may qualify for additional genetic testing. Personal and family history updates may also impact genetic testing options, as well as cancer risk estimates and screening options. We recommend contacting your genetic counselor every one to two years to update your family history and see if any additional genetic testing options are available to you.
Before 2012, genetic testing for hereditary cancer syndromes was often done one gene or one syndrome at a time. Since 2012, technology has improved to be able to test many different genes at once. We now call these tests “panels” since they analyze numerous genes of concern at one time. These panels have made genetic testing cheaper because now one test can be done instead of having to order multiple tests from different labs. Panels also allow us to test individuals for rare hereditary cancer syndromes that previously would not have been covered by insurance.
BRCA1 and BRCA2 genes have been the center of conversations surrounding hereditary breast cancer since the mid-1990s. BRCA1/2 testing that was done before 2012 didn’t always include comprehensive rearrangement testing (also called “BART”) so it’s very possible that individuals who received normal BRCA1/2 test results before 2012 could still have a BRCA1 or BRCA2 mutation that was undetected at the time.
Other hereditary breast cancer genes
In addition, many different genes have long been known to interact with BRCA1 and BRCA2. Studies have now shown that individuals with mutations in these other genes also have an increased cancer risk. Testing for these additional genes is now available.
Hereditary colorectal cancer/Lynch syndrome
Testing for hereditary colorectal cancer has also seen great advances. The most frequently identified hereditary colorectal cancer syndrome is Lynch syndrome, which leads to an increased risk for colorectal, uterine and other cancers. Additional genes that cause Lynch syndrome have been identified and more comprehensive testing of these genes is now available. New causes of hereditary colorectal cancer also have been identified. Individuals who received Lynch syndrome testing in the past could still have a mutation that wasn’t known at the time, or they may have a mutation linked to another hereditary colorectal cancer syndrome that wasn’t tested.
Other hereditary cancers
For people with other cancer types, we now have testing options that did not exist previously. For example, there are now panels available that check 19 genes for hereditary kidney cancer and 13 genes for hereditary pancreatic cancer.
In summary, genetic testing for inherited cancer syndromes has been significantly updated in recent years, and individuals may qualify for additional genetic testing even if they tested negative in the past.