Mutated genes don’t automatically lead to cancer, says Rob Verkerk
Angelina Jolie is the pin-up woman for an entire new industry centered around cancer prevention (see page 20). Just like Jolie, you can find out if you have mutations in one or both of the genes that most affect your chances of getting breast cancer (BRCA1 and BRCA2) and decide whether you want to undergo preventative surgery to slash your risk. If you have the ‘faulty’ genes, you’ll consult with a new-fangled ‘genetic oncologist’ and may well be persuaded to kiss your breasts, ovaries and fallopian tubes goodbye.
Predictive genetic testing will inevitably become an important part of cancer risk reduction in the future. An increasing number of doctors and other practitioners in integrative or functional medicine are already using it. Knowledge of certain gene variation patterns can help a practitioner advise changes to behavior, lifestyle, diet and exposure to environmental chemicals that can reduce the risk of disease and prioritize what modifications are most important at a given time in your life.
But it’s a new field, and there’s a lot we don’t know. One of the most important elements is trying to understand how our genes are actually expressed, not just whether we do or don’t have particular variations in them. In essence, our genes ‘load the gun,’ while our environment ‘pulls the trigger.’ That means you can be dealt a less-than-ideal set of genetic cards, but by controlling your behavior, lifestyle and diet, you can quite drastically affect how those genes are used.
In January, the notion of screening the whole female population for BRCA and other genes related to breast and ovarian cancer risks was reported to be cost effective,1 and the news was sprawled across newspapers worldwide. Public relations companies working for medical interests must have had a field day. But what should be good news, and a major feather in the cap of the cancer prevention movement, rings some alarm bells in my mind.
The approach could certainly facilitate early treatment of cancer. But what are the long-term effects of people knowing that they, and other family members, have some or a full complement of ‘faulty’ cancer genes?
How do thousands of people react to being given this news? Do they act on it and remove ‘at risk’ body parts? Or do they plummet into depression, take to the bottle and indulge in lots of deep-fried foods and candy to drown their sorrows?
Taking the intended ‘right action’ will definitely cause surgeons to start sharpening their scalpels in expectation of the crowds that will be lining their waiting rooms. The new era of genetic medicine has the potential to become a big-money industry. It’s also one that insurance companies are watching closely. Just think about how your genetic results might impact your health insurance premium.
Beyond these unsavory possibilities, what else might health professionals do when counseling or giving advice that would really help people reduce their risk? We know lifestyle, diet and specific nutrients are strongly related to cancer incidence and prognosis, and there is a wide range of nutrients in our diet, or in supplements, that help gene repair – the very thing that is defective in people with the ‘high-risk’ variants of the BRCA1/2 genes.
It’s a tricky juncture for medicine. Do we use our knowledge of the body’s programming to simply jettison parts that might get diseased, or do we take a much broader perspective on gene-environment interactions and give people options that don’t involve drastic surgery? Is genetic medicine making a mistake by continually referring to ‘high-risk’ genes as ‘faulty’?
As Darwin found out, Nature creates variations deliberately; some have benefits, some have disadvantages. Only rarely does it mess up so badly that the software doesn’t allow the hardware of the body to function at all. There are more than 20,000 genes in the human body, and each one has different variations. We don’t know enough about the people who are carriers of the mutated genes but who never contract cancer.
Is it something to do with their environment, their epigenetic background, their whole deck of genetic cards or a combination of all these things?
BRCA genes are no newcomers. They’ve been around 1.6 billion years, and they’re found not just in animals but also plants and fungi. They can be affected by viruses, and recently, in evolutionary terms, they’ve been evolving particularly rapidly in primates, including humans.2 Like so many things about our genes, we still don’t know why.
The idea that genetic screening is highly accurate is flawed in my view. And don’t be taken in by tags like ‘precision medicine’ when it comes to BRCA gene-informed double mastectomies.
There are women with BRCA mutations who don’t want to lose body parts. Instead of handing themselves over to surgeons, they’re making genetically well-informed changes to their diet and lifestyle patterns. Follow-up on these women will be fascinating – and might give us clues that most women on the planet can really benefit from.
In the meantime, we’re flying near-blind, something genetic medicine would prefer that you ignore.
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J Nat Cancer Inst, 2018 Jan 18
BMC Evol Biol, 2014; 14: 155