I attended the Science Friday presentation on the 22nd of November about cancer, genetics, and heredity. The flyers for the presentation themselves were informative and thought-provoking: Cancer is always genetic, but when is it inherited? I would wager that many people, like me, have never thought about this important differentiation. The speaker, Kerry Crandall, gave an informative presentation regarding the causes of cancer and genetic testing. I learned quite a few things, some of which actually had a surprising impact on some things I once thought.
One of Ms. Crandall’s first statements was that when she started working in the field [in 1988], nobody was talking about hereditary cancer. She went on to say that this came up seven years later [in 1995]. This was surprising to me, but it makes sense in light of the percentage of cancers that are actually hereditary. One thing that I learned about cancer and heredity that was quite central to the presentation was that only about 5 – 10% of cancers are hereditary. If I had been asked to guess prior to this experience, I may have guessed that about 75% of cancers were hereditary. Conversely, it is about 70% of cancer that is believed to develop due to acquired changes, which include exposure to carcinogens, the aging process, and chance.
Secondly, I learned about the characteristics of hereditary cancer. These characteristics are that multiple individuals on the same side of the family are affected with the same or related cancers, over multiple generations, with the cancer occurring at a younger age than usual, and no known environmental risk factors. The other types of causes are acquired changes (which are sporadic) and familial. Ms. Crandall stated that family history is that best tool for differentiating between sporadic, familial, and hereditary cancers.
Finally, I learned that testing of multiple gene mutations is sometimes done in a sort of “panel” test. This testing looks for sequencing differences, deletions, and duplications of various genes, and can take anywhere between a few days and a few months to return results.
Ms. Crandall stated that federal and state laws protect against discrimination based on results of genetic testing when it comes to searching for health insurance. She also said that laws are not so helpful when it comes to life insurance.
Relating these facts to microbiology in three different ways is a bit more difficult. Obviously, information about mutations in genes relates to microbiology as we look at the processes through which cells divide and acknowledge that mistakes sometimes happen in that process. The fact that there are 1000 or more mutations of BRCA-1, some of which are “just mutations” that have no dangerous implications that we know of, is just a point of interest. Secondly, when we think about some of the environmental factors that might make up some of the 70% of cancers created by acquired changes, some of those causes in the category of “chance” might include microorganisms like viruses (for example, human papillomavirus and its link to cervical cancer). Finally, a question from the audience about Factor V Leiden clotting disorder piqued my interest. This condition is caused by a gene mutation that causes the clotting protein to deactivate more slowly than it should.
So, how does this affect the way I think? As previously stated, I was completely surprised by the low number of cancers that could be considered genetic. Without having done any research, I thought that my grandmother’s bout with breast cancer automatically meant that I was at a higher risk for breast cancer. However, being that she is the only member of my mother’s family who has had breast cancer, and the only member of my mother’s immediate family to have had any cancer at all, that her cancer occurred at age 72, and the fact that my grandmother was exposed to carcinogens for decades in the form of heavy secondhand smoke while my grandfather smoked cartons of cigarettes per day, it is unlikely that my risk of breast cancer is elevated due to any genetic factors. So, this has had an important impact on my thought.
Secondly, because Ms. Crandall indicated that genetic testing is not indicated for people with no elevated risk, and because I could face discrimination if I was found to carry some gene mutations, I have come to the conclusion that I am very unlikely to ever seek genetic testing to rule out possible inherited cancers. (I might be interested in having testing to determine my genetic origins, however, as my paternal grandmother was an orphan and I’m very curious to know her background. It would be awesome to find some relatives to visit in some faraway land…)
Finally, the 30% instance of familial cancer that is not necessarily related to genetics, but more linked to commonalities in habits and environment, inspires me to pay careful attention to what may be working well in my environment and upbringing. We are a very healthy family – low instances of cancer, obesity, diabetes, heart disease, etc. It seems to me that we may be doing some things right, worth continuing as tradition.
In conclusion, I am happy that I attended this presentation, and found it informative. While I did have trouble linking it solidly to microbiology in three different ways, I do think that there is a very solid link between this information and microbiology as we remember the processes of cell division and the ways that that can be impacted.