Written by Robyn Scherber, MD
Familial predisposition to MPN is something that we have suspected to be occurring for many years. A recent study reported in Blood Journal drawing off of a large cancer database in Europe reinforces this suspicion. When MPNRF shared this report recently, it prompted many good questions from people in the MPN community who wonder whether they or their family members should take action or be concerned about this information.
It may be scary to think that this may mean that your loved ones might be at a higher risk of developing an MPN; however there are a few key points that I would recommend considering:
1) Although the relative risk of developing a blood cancer may be higher if you or a family member has a blood cancer, all things considered, your family member’s risk of developing an MPN is still low.
In the United States, the risk of polycythemia vera is approximately 22 people per 100,000 in the population. According to the article, if you have polycythemia vera the relative familial risk is 7.6. This means that your family members risk is 167 per 100,000 people (also can be thought of as 1.6 in 1,000 individuals. This is still a very low risk. For example, the likelihood of being born with extra fingers or toes (also called polydactyly) is even higher risk (1 in 500).2) Every person is unique, and this represents with unique predispositions and risk factors for every person who has an MPN.
Ultimately, cancer can happen despite our best efforts to avoid it. Both genetics and lifestyle choices are factors that can alter whether – and potentially how –a blood cancer manifests.
Genetics are certainly something that we can not change (at least at this point, although modern medicine is trying to change this). Even people who have the same known genetics can have vastly different manifestations of their mutations. Previous studies have shown that the number of people walking around with a JAK2V617F mutation is much higher than the number of people with a diagnosed blood cancer. Thus, not everyone with genetic mutations has, or may even develop, a blood cancer.
Lifestyle and our environment are also important factors that can influence whether or not someone develops an MPN. To date, modifiable risk factors that have been associated with a higher risk of developing an MPN include smoking or elevated body mass index. If anything, the best advice I can give anyone who is concerned they will develop a blood cancer is to try to modify these risk factors and live as healthy of a life as best you can. This includes trying to quit smoking, eat healthy, and exercise.
3) Having a genetic mutation does not mean that you are going to pass along your mutation to your children.
In general, there are two types of mutations: somatic, which basically is a mutation that someone has acquired over the course of their life, OR germline, which are inherited mutations passed along in families. Mutations for MPNs can be either one of these. Just because you have a specific mutation, it does not necessarily mean that you will pass this genetic mutation along to your children. In fact, most MPN mutations are acquired over time. However, we are understanding more that there may be other mutations than the most common mutations (i.e., JAK2, Calreticulin, or MPL) that can be potentially passed along that may allow someone to acquire these additional mutations over time.
4) Many cancer types have been found to run in families.
Cancers running in families is a not a new concept. Breast cancer, kidney cancer, brain cancer, colon cancer, skin cancer, thyroid cancer, and adrenal cancer are just a few types of cancers that can be associated with familial genetic changes. Although there are known genes that can be associated with familial cancers in other cancer types, we currently do not have any fancy testing widely available to test if your cancer runs in the family or not for MPNs. Efforts are underway to do genetic mapping to see if we can get a better idea of what genes may be associated with familial cancers in MPNs.
5) What do I do if I worry someone in my family has a blood cancer?
It is important to have your family members do their best to stay healthy and get regular check-ups with their primary health care provider. If there is a suspicion that someone you love may have a blood cancer, I would recommend that they be encouraged to have their blood counts checked. For someone with abnormal blood counts, it may be worthwhile to have close monitoring or be referred to a blood specialist for closer monitoring and potentially testing.