Heredity

author/s: Dr Xavier Llor Farré

 

Have I or have I had relatives with this or with other types of cancer?

One of the most important factors concerning the risk of colorectal cancer has to do with whether we have had one or more relatives diagnosed with this type of cancer or whether there have been other types of cancer in the family. Even though the highest percentage of colorectal cancer appears in people with no familial history, the risk of a person to suffer from this type of cancer is higher if there is a familial past history. The higher the number of affected relatives, the greater the risk will be. A different matter is families with hereditary syndromes such as familial adenomatous polyposis or Lynch´s syndrome in which the risk to suffer from colorectal cancer for each member of the family nearly reaches 50%.

 

Is colorectal cancer inherited?

The hereditary component in this type of cancer is very important. We already know that if the mutated form of some specific genes is inherited, the risk to suffer from colorectal cancer reaches approximately 100%. At this time, not all the responsible genes have been identified.

 

When can I suspect that my family may be affected by a hereditary syndrome?

You can suspect colorectal cancer when several family members have suffered from this specific type of cancer or other types of cancer, mainly endometrial cancer. Also, when there have been cases of young family members (under 50) diagnosed with cancer.

 

What do I have to do if I have relatives with colorectal cancer or other types of cancer?

You should seek help from your specialist, who will suggest the possible strategies to follow according to your particular risk and your age, referring you to have a genetic consultation if a case of familial syndrome is suspected.

 

What is genetic counselling?

Genetic counselling is a personalised evaluation carried out to determine the likelihood of developing a hereditary syndrome, in this case, colorectal cancer. The patient will be given the appropriate recommendations and if deemed applicable, genetic testing will be ordered to help establish whether the mutation affecting the family has been inherited.

 

Are there any tests to detect if a predisposition to colorectal cancer has been inherited?

Yes, there are. Even though at this time we do not know all the genes that are involved in hereditary colorectal cancer, if a mutation is detected in one of the identified genes in an affected family member, the other members of the family will be able to be tested to see if such mutation has been inherited. This will enable us to find out the high risk of developing colorectal cancer or other types of cancers related to colorectal cancer.

 

Are these tests reliable?

If we are able to detect a mutation in an affected family member, all the other members will have to be tested by means of a simple test. Those who have not inherited the mutation will have the same risk as the rest of the population to develop colorectal cancer and thus, it will not be necessary to do any screening until they are 50, just as with the rest of the population with no symptoms. Those individuals who have in fact inherited the mutation will have to follow the established guidelines to avoid the development of the cancer.

 

What are the family syndromes?

The most important family syndromes are Lynch´s syndrome, also known as non-polyposic colorectal cancer or without polyps, and familial adenomatous polyposis, characterised by the presence of a large number of polyps throughout the entire length of the colon.

 

Can I prevent colorectal cancer?

Colorectal cancer is one of the most preventable cancers due to its generally slow growth and the significant knowledge acquired on familial syndromes. In all cases, the most important is to know what guidelines to follow and what needs to be done in each particular case.