Hereditary cancer syndromes

This section covers the following topics:

What is a cancer syndrome?

In medicine, a syndrome refers to a collection of symptoms or signs with a common cause. Sometimes doctors refer to certain inherited mutations as causing a syndrome. Not all inherited gene mutations are associated with a syndrome, and some are associated with more than one syndrome or referred to by more than one name. This can be confusing for people who are trying to understand the medical risks associated with their mutation. The table below lists different syndromes and the genes associated with them. If you have been told you have a hereditary cancer syndrome, it's very important for you to learn your exact mutation. Make sure that you receive a copy of your genetic test results and discuss your results with a genetics expert. If you are uncertain or do not have a copy of your genetic test results, you may request a copy from your health care provider. Some testing labs may make the results available to you directly through a patient portal. 

The two most common hereditary cancer syndromes are hereditary breast and ovarian cancer syndrome (HBOC) and Lynch syndrome. 

Hereditary breast and ovarian cancer syndrome (HBOC)

HBOC is a name given to inherited mutations in one of two genes:

• BRCA1
• BRCA2

Breast and ovarian cancer are the two most common cancers in people with BRCA1 and BRCA2. However, "HBOC" can be misleading because mutations in these two genes can also increase the risk for pancreatic, prostate and other cancers. Because it involves breast and ovarian cancer, “HBOC” may imply that these genes don't affect men. However, half of people with a BRCA1 or BRCA2 mutation are male. 

There are guidelines that outline what is known about the cancer risks associated with HBOC and options for screening, prevention and treatment of cancers in people with inherited mutations in these genes. In the past, the guidelines were the same for both genes. As research on these genes has continued, experts have found that the cancer risks for each gene are somewhat different from one another. For this reason, experts have started to separate out the different risks and medical options for BRCA1 and BRCA2. Despite these differences, some references still use the term HBOC when referring to inherited mutations in either gene. 

If you have been told that you have HBOC, it is important to know whether the mutation you inherited is in a BRCA1 or BRCA2 gene, so that you can make informed decisions about your medical care. 

Lynch syndrome

Lynch syndrome is caused by an inherited mutation in one of these five genes:

• EPCAM
• MLH1
• MSH2
• MSH6
• PMS2

People with Lynch syndrome have an increased risk for colorectal, endometrial and other cancers. The cancer risk varies by gene mutation, therefore it is important for people with Lynch syndrome to know which gene mutation they have.

In the past, the risk-management guidelines were the same for people with an inherited mutation in any of the Lynch syndrome genes. As more research has shown different cancer risks for each gene, experts have started to separate the risks and medical options for each individual mutation. Despite these differences, some references discuss Lynch syndrome as though inherited mutations in these genes carry the same risks. 

If you have been told that you have Lynch syndrome or HNPCC, it is important to know which gene has a mutation, so that you can make informed decisions about your medical care. 

In the past, Lynch syndrome was also referred to as “hereditary nonpolyposis colorectal cancer” (HNPCC). This term has fallen out of favor because mutations in these genes also increase the risk for other cancers besides colorectal cancer. 

Cancer syndromes and associated genes

This chart lists the genes that are associated with some of the most common hereditary cancer syndromes.