What is the difference between spontaneous v. familial cancer genes such as BRCA?

One of the major questions that we get with a young person with cancer is, “Will I pass on the cancer disease to my child?” So one of the things we talk with patients about is that the majority of cancers actually arrive spontaneously. So over 90% of cancer diagnoses are not carried through a family, but actually arose spontaneously as a consequence of, for example, sun exposure, or other factors, many of which we just don’t understand. But those are not genetically-based diseases; rather, they are spontaneous mutations that arose in an individual that gave them breast cancer or melanoma or some other kind of cancer.

In a small percentage of cancer cases, these are associated with what we call a familial, or an inherited, gene, that causes one generation of a family to pass on that cancer gene to another generation. And the best example of this are the BRCA 1,2 cancer patients who have a mutation in a gene called the BRCA gene. Now, those families are fairly well aware that within their pedigree exists a gene that can give them a higher risk for breast and ovarian cancer. So for a patient who has a family history of those kinds of cancers, having the option to preserve fertility early is really an important one for them, so that then they can go on and make decisions about how they might manage the cancer by, for example, having a mastectomy or an ovary-ectomy, before the cancer really arises in those tissues.

The decision to preserve fertility in the majority of cancer patients is one that is not associated with delivering a gene to the next generation. For BRCA patients who decide to preserve fertility through some of these advanced technologies, there are ways of actually then selecting the embryos so that you don’t actually pass that gene on to the next generation. So we really want to provide as much information as possible to all these patients—either those who have spontaneous cancer or those with familial cancer genes—to give them the best information on their biology and how that impacts the next generation.