Why family history affects prostate cancer risk

Why family history affects prostate cancer risk  

All men need to have the talk – the talk with their male relatives on who has had prostate cancer or who has not.  A strong family history of prostate cancer is a powerful player in detecting a man’s risk of this potentially deadly disease.  Other than skin cancer, prostate cancer is the most common cancer in American men making it imperative a man knows his grandfather’s, father’s and any brother’s medical history.   But, men rarely talk about their health history with other men in their family.  Yet knowing and being aware of medical conditions, both past and present, can literally save a man’s life.  Just like having a family history of type 2 diabetes is a known strong risk factor for developing that disease, family history is a substantial risk factor for prostate cancer and should not be ignored or deemed unimportant.

It has been known for some time that men with a family history of prostate cancer are at a higher risk of getting it themselves.  Just how high that risk is and how likely it is a man with a family history will get a mild or aggressive (fast-growing) type of the disease can be useful information in counseling men who have prostate cancer in the family.  The more information a man has on the risks of getting prostate cancer can help him make his own decisions about testing and treatment.

How strong is having a family history of prostate cancer?

A study conducted in Sweden in which researchers reviewed the medical records of 52,000 men with brothers and fathers who had prostate cancer found the following information:

·      Men with a brother who had prostate cancer had twice as high a risk of being diagnosed as the general population.  They had about a 30% risk of being diagnosed before age 75, compared with about 13% among men with no family history.

·      Men with a brother who had prostate cancer had about a 9% risk of getting an aggressive form of prostate cancer by age 75, compared with about 5% among other men.

·      Men with both a brother and father with prostate cancer had about 3 times the risk of being diagnosed as the general population.  They had about a 48% chance of getting any type of prostate cancer, compared with about 13% among other men.

·      Men with both a brother and father with prostate cancer had about a 14% chance of getting an aggressive type of prostate cancer by age 75, compared with about 5% among other men.

Other findings from the Swedish study

Also found in this study was that while the number of close relatives with prostate cancer affected the risk, the type of prostate cancer in the family did not have a strong effect on risk.  For example, the risk of an aggressive prostate cancer was just as high in men whose brothers had the mildest form of prostate cancer as those whose brothers had an aggressive type.

One thing for men to keep in mind about this study is that it only looked at men living in Sweden.  In other areas of the world where prostate cancer screening rates are fairly high and the population of people come from similar genetic backgrounds, the results from this study could be similar.  However, it is not clear how well these findings apply among people with different genetic makeups.

Takeaway message

Obviously, a man is unable to change his family history of prostate cancer.  But since it is known there are multiple genes a man inherits from his parents that can increase his risk of developing prostate cancer, at least a man can decide  just how high his risk may be.  There is an advanced DNA test that may identify gene mutations that increase a man’s risk of getting the disease.

A 2016 study published in the New England Journal of Medicine found that a significant proportion of men with advanced prostate cancer are born with DNA repair mutations and they believe that genetic testing could be a valuable part of the treatment for advanced prostate cancer.  This genetic testing for these mutations could identify men with advanced prostate cancer who may benefit by being offered drugs such as PARP inhibitors which are showing to be effective in men with these mutations. 

In the meantime, whether a man has a family history of prostate cancer or not, all men beginning at age 40 should have a baseline prostate specific antigen (PSA) test and then, discuss with his doctor on what the recommendation should be on the frequency of PSA testing for him.  Men should also be aware of other risk factors for prostate cancer.  The earlier prostate cancer is diagnosed, the better chance of beating it back and living a long life.