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Jul 14, 2019 03:19PM
Jul 14, 2019 07:44PM
Diane, the thing about risk models is that they are not absolute. One person might have a 90% chance of developing breast cancer (BRCA+ plus other high risk conditions and a high risk lifestyle, for example). Another person might have a 3% chance of developing breast cancer (no risk factors other than being female and getting older, and a pristine lifestyle). Obviously the first person is at significantly higher risk than the second person, but it could turn out that the first person doesn't develop breast cancer but the second person does. This doesn't mean that the risk models and the criteria evaluated were wrong. It's just a question of odds. The first person, although very high risk, still has a 10% chance of never developing breast cancer. And the second person, although very low risk, still has a 3% chance of developing breast cancer. So if the first person is lucky and the second person is unlucky.... But it doesn't mean that the assessments of their risk were wrong.
The best I can tell, breast cancer develops because of a confluence of factors. As an example, someone who is BRCA positive starts off with one defective gene - this is the gene that controls the growth and management of breast tissue. This alone doesn't mean that she will develop breast cancer. What it means is that if her other copy of the same gene also craps out (we have two copies of the gene), then she will develop breast cancer. What might cause this other copy of the gene to fail? Aging is the big one that hits most of us - some of our genes wear out and simply stop functioning properly as we get older. Accumulated lifetime estrogen overload might do it. If she has dense breasts, the biology within her body that causes the breast density might do it. Or maybe it was exposure to radiation. Or exposure to environmental toxins. Or consumption of foods that drive biological/molecular changes that cause more estrogen (or something else) that down the line triggers a change in this gene. Most likely, it's a combination of factors that each directly or indirectly make a small change that weakens or damages the gene, until one day, the gene gives up and cries uncle. Once the gene fails, there is nothing controlling the growth of breast tissue cells and the environment is ripe for cancer cells to thrive and spread.
I believe the process is the same for those who do not carry a known breast cancer gene. It's an accumulation of factors that together wear down the genes, cause failure, and allow breast cancer cells to develop and grow. As for which factors, it's probably a different combination for everyone. There is a long list - let's say 75 items - that are known to increase breast cancer risk. This includes things that are inherent to us as humans (we age) and females (we have estrogen), things that we are exposed to (those canned foods we ate as kids, toxins in the air as we take a walk around the neighbourhood) and things that we consume (even fruit juice, it seems). It includes factors that have a direct impact - radiation, for example, might directly harm the cells. And it includes factors that have an indirect, convoluted impact; no one knows why alcohol slightly increases breast cancer risk and it appears to be through a multi-step process. Most importantly, not everything on the list affects everyone. For each of us, there are tick marks by some of the items on the list. These are the items that affect us personally by impacting and changing our genes or cells. My tick marks will be different than your tick marks. Then it's a question of how much we are exposed to and affected by each of these factors with the tick marks, and whether in total the damage caused reaches a level that allows breast cancer to develop and thrive. Most women never get to this level of exposure. Someone who is obese and has terrible eating habits might appear to be high risk, but it's possible that her breast cancer risk isn't affected by any of these factors - no tick marks on these items. Those of us here all reached that unlucky combination of factors that finally created an environment that allowed breast cancer to develop. But which factors caused it, and in what quantities of exposure, it's impossible to ever know. And it's different for every one of us.
All that to say that the risk models and the lists of things that drive breast cancer risk aren't wrong. But they are broad and population based - they can't be applied to any one individual. And in the end, whatever the odds we face from our unique combination of risk factors, some of us end up being lucky and some of us end up being unlucky.
Edited for typos/grammar only (gotta love autocorrect, or not!)
“No power so effectually robs the mind of all its powers of acting and reasoning as fear.” Edmund Burke