Recognize the risk of cancer in your family
You may remember stories of your father’s military service and your mother’s hometown, but how much do you know about your family’s medical history? In particular, do you know whether anyone on your mom or dad’s side ever had cancer? “Family history can be one of the first lines of defense in preventing cancer,” says Dr Huma Q Rana, clinical director of the Centre for Cancer Genetics and Prevention at Harvard-affiliated Dana-Farber Cancer Institute. “If you can get a picture of the patterns of cancer on both sides of your family, you can screen for certain cancers more closely and either prevent them or catch them early.” And if you do get cancer, your genetic heritage might provide clues to help your doctor choose targeted therapies to treat it.
All in the family
Your family’s cancer history should include your first-degree relatives – father, mother, and siblings – as well as your second-degree relatives, if possible – aunts, uncles, and grandparents. Note what type of cancer occurred, the age at diagnosis, as well as the age at which the person died and the cause of death. The first-degree relatives tend to be the most crucial. “This is because you share 50% of your DNA with them. A genetic susceptibility to cancer does not guarantee that you will get cancer, but you have a higher risk,” says Dr Rana. Lifestyle and environmental factors
also play a part in your cancer risk assessment. For instance, if your father died of lung cancer in his 80s and was a lifelong smoker, the cancer probably did not reflect a strong genetic trait. If you can pinpoint a certain hereditary cancer in your family, you may run the risk of developing other types of cancers associated with it. For instance, 3% of people with colon cancer have Lynch Syndrome, an inherited disorder that also increases the risk of cancers of the stomach, kidney, bladder, skin, and (in women) uterus. Of course, a family medical history can be difficult to obtain. Family members can be estranged or not forthcoming about their history of cancer. And odds are your older relatives have passed away. Even if you can’t create a complete family cancer history, any medical information you can provide your doctor is helpful. “For instance, knowing if family members have died of other causes and age at diagnosis or death can help build a family history profile,” says Dr Rana.
Pass it along
Who has been diagnosed with cancer in your family affects not only you, but also your children. For example, if your mother died of breast or ovarian cancer, which can sometimes result from a mutation in the BRCA1 or BRCA2 genes, you might not worry about it yourself since these are woman-specific cancers. But you may have inherited a mutation that is also associated with the development of aggressive prostate cancer, says Dr Rana. And even if you remain cancerfree, you could still pass along that mutated gene to your daughter, which puts her at a higher risk for breast or ovarian cancer. In fact, a 2011 study found that 24% of women with ovarian cancer had an underlying mutation. “That’s why it’s so important to try to put together as detailed a medical history as possible. It’s not just for you, but something you can share with your children and grandchildren,” says Dr Rana.
Your family cancer history is only the first step. A genetic test can help clarify whether you have one or more specific genetic mutations. Genetic testing involves seeing a genetic counsellor or other specialist who assesses your family history and explains the risks and outcomes of testing, like anxiety from inconclusive results, or the need for closer cancer surveillance if you have a mutation. A simple blood or saliva test looks for mutations in a number of genes related to cancer. You typically get the results in about four weeks. Years ago, genetic testing was expensive, but it is now more affordable and accessible. Think you’re too old to worry about cancer? Think again. Cancer, like some relatives, can always show up unexpected. “You can get diagnosed with cancer late in life, so don’t think you are home free if you reach a certain age cancer-free,” says Dr Rana. “Know your family history and talk to your doctors about your possible risk and strategies for prevention.”
Knowing your family’s history of cancer can help you better assess your own risk. This sample family tree depicts a family with a history of ovarian, breast and prostate cancer.