Cancer, Inherited Cancer & Lynch Syndrome (Page Under Construction)
Do I have an inherited condition? In the majority of cases, cancer is not inherited. In the case of colorectal cancer, it is common in the general population, affecting 1 in 14 men and 1 in 19 women at some point during their life, more commonly after the age of 60. Most cancers occur sporadically or ‘out of the blue’. However, in about 5-10% (5-10 in 100) of individuals who develop colorectal or endometrial cancer, cancer is caused by a genetic alteration (a change in their genetic code instructions, or what we are going to call a ‘genetic change’). In about 3% (3 in 100) of all colorectal or endometrial cancers, the genes affected are those whose task is to repair abnormalities when cells are made.
These repair genes (called DNA mismatch repair genes) protect us from developing certain cancer types. This is the case in Lynch syndrome, which is the most common cause of inherited colon and endometrial cancer. It affects 1 in 278 people. How is Lynch syndrome diagnosed following a cancer diagnosis? It is not straightforward to find out if a cancer is inherited or sporadic (out of the blue). To find out if someone has an inherited cancer that is being passed down in the family, there are different tests that need to be performed. In addition to taking a detailed family history, for Lynch syndrome, some tests are performed on the cancer (tumour) sample.
This is because Lynch syndrome leaves a fingerprint in the tumour. The initial tumour tests are immunochemistry (IHC) and microsatellite instability (MSI): • Immunochemistry (IHC). Every person diagnosed with colorectal or endometrial cancer has IHC performed on their tumour. IHC looks at the expression of the proteins produced by these ‘mismatch repair’ genes. If there is a loss of expression of any of these proteins, you may be offered genetic testing to find out if you have Lynch syndrome. There are some short and easy-to-understand leaflets which you can access here: o IHC & bowel cancer o Recording your bowel cancer IHC results card IHC & womb cancer o Recording your womb cancer IHC results card • Microsatellite Instability (MSI). This is another type of genetic test on the tumour to find out if you are likely to have Lynch syndrome. If the result is positive, you might have Lynch syndrome, and you will be offered genetic testing. o MSI & bowel cancer
Additional testing may be required using MLH1 promoter Hypermethylation (MLH1 Methylation). In some cases, following an IHC test, this test might be necessary to clarify if the cancer is sporadic and originates in the tumour cells, or if it could possibly be inherited. If the result of this test shows that the tumour sample is methylated, it clarifies that the cancer is sporadic and originates in the tumour. If not, it is possible that you might have Lynch syndrome and will be offered genetic testing.
If tumour test results show that there is a possibility that you might have Lynch syndrome, you will be offered genetic testing. Genetic testing will be able to confirm if you have Lynch syndrome.
How is Lynch syndrome diagnosed if you have an affected close relative? If you have a close relative with a diagnosis of Lynch syndrome, you might be offered genetic testing to find out if you have inherited the genetic change (or genetic alteration) that is causing Lynch syndrome in your family. This form of genetic test is called “predictive genetic testing” and will only look for the genetic alteration that have been identified in your family. The test will not look at the rest of your DNA to identify other genetic conditions. Genetic testing for Lynch syndrome following a cancer diagnosis 7 Genetic testing for Lynch syndrome will involve having a blood test. DNA will be extracted from your blood to look for genetic changes (or variants) that cause disease or increase your risk of developing a disease. This testing takes approximately three months to complete. Genetic testing for Lynch syndrome helps your doctors to understand you and your family’s risk of developing cancer in the future. Positive test results will also help your doctors to understand the treatments you may require. They will use it to develop an enhanced cancer prevention programme just for you. If you have cancer, you will be eligible for therapies that are known to work best for people with Lynch syndrome, such as immunotherapy. Having genetic testing is optional. Your decision will not affect the standard of care you receive. However, knowing you have Lynch syndrome will give you and your family access to personalised cancer prevention programmes, advice and treatments. It will also enable testing of other family members and, if appropriate, they will also be provided with a personalised cancer prevention programme to help reduce the chance of further cancers developing in the family. Genetic results Genetic test results do not always give a clear answer. This is because the science of genetics is still in its infancy. For this reason, and for clarity, your results will be classified as positive, uncertain or negative: • Positive: a genetic change for Lynch syndrome is identified This result would confirm the diagnosis of Lynch syndrome and provide an explanation for why you developed cancer. Your cancer team will use this information in their management decisions and will discuss this with you further. You might be considered for additional therapies, and they will offer predictive genetic testing to your first-degree relatives (parents, siblings and children), as they might carry the same genetic change. • Uncertain: Genetic change (or variant) of unknown clinical significance is found A genetic change is found, however, it is not certain that it is the cause of your cancer. If appropriate, there may be further analysis of your tumour or other family studies recommended. Unfortunately, genetic testing cannot be offered to your family members at this time but cancer surveillance for you and your family will still be recommended. • Negative: No genetic changes were found This result doesn’t rule out an inherited condition. It might be that the limited knowledge we have about genetics means we are unable find a genetic change currently. If appropriate, there may be further analysis of your tumour recommended, to try to clarify if you have Lynch syndrome. Unfortunately, genetic testing cannot be offered to your family members but cancer surveillance for you and your family will still be recommended. Screening recommendations for you and your family will follow the Lynch-like syndrome recommendations, which your clinician will tell you about.
Genetic testing for Lynch syndrome following the diagnosis of a family member If you have a first degree relative (parent, sibling, or child) with Lynch syndrome, you will be offered “predictive genetic testing” to find out if you have the genetic change or alteration that have been found in the family. DNA will be extracted from your blood to look for the familial genetic change. Having genetic testing is optional. Your decision will not affect the standard of care you receive. However, knowing you have Lynch syndrome will give you access to a personalised cancer prevention programme and advice. It will also enable genetic testing of your children when they reach the age of 18, or access additional family planning options if you don’t have children yet. Genetic results It is important to clarify that this genetic blood test will only look at whether you carry the familial genetic change. It will not look at any other part of your DNA. For this reason, there are only 2 possible outcomes from this predictive genetic blood test: 1. You are found to carry the familial genetic change This will confirm your diagnosis of Lynch Syndrome. You will be offered a personalised screening programme which will include a two-yearly colonoscopy from the age of 25 or 35 depending on the familial genetic alteration, to reduce the risk of bowel cancer. In this case, your children or future children will have a 50% chance of inheriting this genetic change. They will be offered this genetic blood test when they are 18 years old. If you haven’t had children yet, you will be offered additional family planning options. 2. You don't carry the familial genetic change In this case, you have not inherited Lynch syndrome and your risk of developing bowel cancer or any other cancer will be the same as the general population. You will not need any special or enhanced cancer screening. Your children will not inherit this genetic change as you cannot pass on something you don’t have. Psychological Concerns Genetic testing can bring up a wide range of emotions in people for a number of different reasons. This is particularly the case in predictive testing where a result can predict that in the future you might become unwell. As discussed, not everyone with Lynch syndrome will develop cancer, and leaving with uncertainty can be challenging. However, everyone is different, and many people find that knowing that they carry a particular genetic change can give them certainty, give them the power to make decisions, and encourage them to take control in their personalised cancer prevention programme. Insurance Implications of Genetic Testing 9 Currently there is an agreement between the insurance companies and the department of health that means that if they are a member of the British Association of Insurers, they should not ask for the results of predictive genetic tests. If you are having difficulties in arranging insurance, this might be due to your family history of cancer, rather than your genetic results. It can be helpful to talk to a company that is more experienced in dealing with Lynch syndrome. A member of Lynch syndrome UK might be able to direct you to cancer friendly companies and may be able to help with this if necessary. If your genetic result is negative, you might want to disclose this to your insurance company. If you have any questions about how your genetic test could affect your insurance, more information is available from: • The Association of British Insurers • The Code on Genetic Testing and Insurance • Insurance implications for individuals that going to have a predictive genetic blood test are different than people that are diagnosed with Lynch syndrome following a cancer diagnosis (called diagnostic genetic testing). More information is available from Genetic Alliance UK. What does my genetic test result mean? After approximately three months (or 1.5 months of you are having a predictive genetic blood test) you will be given your genetic test results. You have been waiting for this for 10 what it might feel like a long time. Now that you have spoken to your team and have your results, you might have some questions. Please read the information below as many times as you need so you can understand your results and its implications for you and your family and, most importantly, what can you do to reduce or prevent cancer and balance out the risk. The main concern in Lynch syndrome is colorectal (bowel) cancer. For women, endometrial (womb) cancer is also a concern, and to a lesser degree ovarian cancer. There is small increase in the likelihood of developing a few other cancers: pancreatic, kidney, urinary tract, skin, brain and gastrointestinal cancers. However, these other cancers are seen only occasionally, and the increased risk is small – generally less than a 5% increase if you compare this risk to rest of the general population. The risk or likelihood of developing cancer depends on three factors: age, gender and which gene is implicated: • Age The likelihood of developing cancer is very low at an early age, including for people with Lynch syndrome. Cancer prevention bowel check-ups for people living with Lynch syndrome start at the age of 25-35. The likelihood of developing cancer increases with age, so people with Lynch syndrome will have bowel checks every two years. • Gender Men tend to have a higher risk of developing colorectal cancer as compared to women. However, women have the additional risk of endometrial and ovarian cancer. • Gene Different genes have a different likelihood of contributing to the development of cancer. There are some websites that can give you percentages of risk. It can be difficult to look at graphs and make sense of the information, especially when the information is personal to you. If you do wish to calculate your risk, it is recommended to do this with a healthcare professional, who can interpret and personalise the information for you and answer your questions appropriately. However, if this is something that you would like to look at on your own, you can visit the Prospective Lynch Syndrome Database. Prospective Lynch Syndrome Database help If you would like to have a look at your risk on your own, here are some helpful tips that will help you to look at the graphs. There are 3 boxes and a current age bar that you need to select to add your personal information. There are additional taps at the top of the page for calculations for people with and without a previous cancer diagnosis. In addition, please note the acknowledgement in the database on PMS2. They state that “the number of PMS2 carriers included in the studies are insufficient for reliable conclusions. Risk estimates for PMS2 carriers should therefore be interpreted with caution” Information that you need to personalise to look at your risk: