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I've Got the BRCA-Positive Mutation Gene -- How Do I Interpret My Hereditary Risk for Getting Breast and/or Ovarian Cancer?

04/27/2015 05:24 pm ET | Updated Jun 27, 2015

In her late 40s, Jane was diagnosed with the BRCA 1 and 2 genetic mutations that placed her at high risk for developing breast and ovarian cancer. Going online, she notes her risk percentages for getting cancer differ somewhat from site to site. She asked me, "How can that be?" In talking with her genetics counselor she noted: "I was a bit numb, so I didn't really listen to her explaining these risk numbers." However after her counseling session and reflecting on her risk percentages, she told me: "I just guess it means I'm going to die if I don't get preventative surgery."

Jane's experience is not unusual among the BRCA-positive mutation women I have interviewed concerning their genetic testing experience. Hereditary cancer risk is usually expressed as a percentage that goes from 60 to 90 percent for BRCA1 and 30 to 85 percent for BRCA2, compared with 12 percent for women without the BRCA-positive mutation. However, sometimes these risk intervals can change, especially when they are based on different life span estimates usually that usually assume up to ages 70 or 80. In addition, website risk numbers are estimated percentages based on large population samples. As more research findings become available, these population hereditary cancer risk estimates will change overtime. In addition, there will remain variations in these numbers because these estimates are based on using different study protocols, methods and populations. There is little attention paid in the medical field as to just how much these risk percentages can vary as well as the variability of hereditary cancer risk among BRCA-positive women.

Most BRCA-positive mutation women are often not aware of these hereditary cancer assessment risk fluctuations. How, then, can BRCA-positive women make more precise medical decisions regarding their cancer risk and whether to wait and watch and/or whether they should have preventive surgery?

There are some strategies women can employ to determine their personal risk for cancer. For example, knowing the type and site of your particular genetic mutations is important, as some common genetic variants are associated with lower cancer risk as opposed to more rare genetic variants. The recent move to have more public information about the long-term impacts of certain genetic variants overtime is now become more publicly available and this should help give women the longitudinal impact data they also need to assess their cancer risk over time.

In addition, your personal hereditary risk varies depending upon your age and your particular cancer family history. Your cancer risk is greater the stronger the history of cancer in your family line. How many of your relatives died from cancer and died at a young age? Your risk may be higher if your ancestors come from a population whose rates of hereditary cancer are known to be higher. Also important to assess in this mix are your own lifestyle habits -- those habits that may serve to enhance or stave off one's overall cancer risk -- factors such as how often you exercise, as well as your level of alcohol consumption etc.

It's also important to understand that assessing risk levels for hereditary cancer is at its core, a subjective assessment, as there are few "pure" models of cancer risk that don't contain a subjective element. Epidemiologists make subjective judgments regarding those factors that should go into determining risk when they calculate risk numbers. They must decide on what specific populations to derive their risk assessment model estimates. For the most part these risk estimates rely on retrospective population data that contains a variability of risk factors (smokers/non smokers, differences by ethnicity and race and so on) that are not always the same for all statistical cancer risk models. They must also decide on exactly what mix of population characteristics to include/exclude in their target population. There is also the subjective judgment of each BRCA-positive mutation women who gathers all this information. To what extent will she then filter this risk information when deciding the next steps she will or will not take to stem the tide of getting cancer?

My current research into women who test positive for the BRCA-genetic mutation and what medical decisions they make next finds that many women rely on their own family's cancer history. In addition, the women in my study are also influenced by a range of other social and psychological factors that tend to come into play when assessing their risk and making medical decisions. For example, some women are able to tolerate risk and/or uncertainty in their lives in general, and part of this comes from relying on the cancer narratives that reside within their own families. They may have a mother or close relative who had hereditary cancer and they use family hereditary cancer narratives as a "cancer clock" that guides their determination of their overall risk for cancer. These narratives also help women determine the timing of their medical decision making with regard to when, or if at all, they will get preventive surgery.

There are other BRCA-positive mutation women in my study who have little or no history of cancer in their own families, and these women are challenged in their quest to figure out just how to assess their immediate and long-term hereditary cancer risk. Sometimes, they tend to rely on the overall cancer risk numbers they garner from medical personnel and genetics counselors, but they often wind up having a hard time figuring out what these risk numbers mean.

It behooves the medical profession who relate hereditary risk assessment percentages to do so in a way that women can interpret the subjective nature of these data and offer more guidance on just how at risk women should apply these numbers in the context of their own lived experience.

Sharlene Hesse-Biber is a Professor of Sociology and Director of the Women's and Gender Studies Program at Boston College. Her latest book is titled, Waiting for Cancer to Come: Genetic Testing and Women's Medical Decision Making for Breast and Ovarian Cancer. Visit her website: www.hessebiber.com