The recent news about Angelina Jolie and her bilateral prophylactic mastectomy has brought renewed attention to the high risk of women with BRCA gene mutations of both breast and ovarian cancer. I would agree that Jolie’s decision to undergo surgery was a reasonable choice. It is well documented that bilateral mastectomy is one of the most effective ways to limit the risk of and mortality from breast cancer in women with a BRCA gene mutation, particularly when performed before the age of forty. However, that’s not all there is to it. While family history can be an important indicator of breast cancer risk, there’s a critical point that often gets overlooked. Jolie’s situation and its extensive coverage have presented a tremendous opportunity for the medical establishment and Jolie to address a commonly held misconception that has potentially dangerous consequences – that the leading risk factor for breast cancer is a gene mutation resulting in a hereditary predisposition to cancer. This, in part, reflects confusion about the difference between “hereditary” and “genetics,” with regard to cancer risk. Hereditary risk factors are changes in the genes you inherit from one or both of your parents, which are present in all cells in your body. In families with a very high cancer risk, some family member(s) might inherit that abnormal gene. It is important to note that while virtually all cancers are “genetic” (resulting from changes in specific genes), most cancers are not inherited but, rather, reflect the genetic changes that occur within the DNA of that cell. Over a period of years, a mutated cell can give rise to generations of new cells that acquire additional genetic changes, eventually resulting in an actual cancer. Thus, strictly speaking, all cancer is “genetic” but not necessarily inherited. I coauthored a 2006 study in Connecticut conducted by Environment and Human Health, Inc, surveying a large sample of women without a cancer history that assessed their understanding of breast cancer risk. The results reaffirmed how frequently the public misunderstands and overestimates the role genetics and family history play in breast cancer risk, with one quarter of the women believing that 75% of all breast cancers are caused by inherited gene mutations such as BRCA-1 or 2. What we do know is that only 15% of breast cancer in the US is related to a strong family history, and only 8-10% of breast cancer has a defined inherited genetic predisposition. On the other hand, if a woman does have a high risk BRCA-1 gene mutation, she has an 85-95% risk up until age 70 of getting breast cancer and a tendency toward earlier onset of both breast and ovarian cancer. The problem is that women are confusing the high risk in individuals that have the gene mutation with the general risk of getting breast cancer. What are the consequences of this misunderstanding? That many women without a family history or genetic predisposition to breast cancer are underestimating their actual risk of getting breast cancer and are not taking adequate preventative measures, like screening. I even hear “I don’t have a family history, so I don’t have to worry” from my own patients. A critical piece of the puzzle is the strong environmental component that has led to in the dramatic growth in the incidence of breast cancer in all women. Many of these environmental factors are known, including reproductive history, hormonal factors, diet, and lifestyle. But something has also changed in the last 40+ years that appears to have increased the lifetime breast cancer risk in carriers of an inherited BRCA-1 or 2 gene mutation from 20% up to 85%-95% risk, similar to the marked increase in non-inherited breast cancer incidence over this same period. Unfortunately, this is rarely talked about. And this cannot be due to an increase in the frequency of these genetic mutations, because it would take hundreds-to-thousands of years for this magnitude of change to occur. Despite all the media coverage, public awareness campaigns, and money spent on disseminating information on breast cancer, this critical issue continues to be misunderstood. Despite the evidence of high risk that women with these mutations face, having the gene is not destiny. Beyond the aggressive surgical approaches currently being employed, there is a critical need to determine what specific environmental factors are responsible for the dramatic increase in breast cancer. The ultimate goal must be to seek the safest strategy to prevent this disease in all women.
Posted on: Fri, 04 Jul 2014 14:49:02 +0000
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