We're bombarded with mixed messages about cancer every day, but the truth is we're still a way off understanding it. While many may believe a healthier lifestyle can provide a level of immunity, there is no denying the considerable influence your genes have on your disease susceptibility. Teasing out exactly how much your genes play a role however, and which gene variants may be 'nasty', is a difficult task requiring large scale, expensive studies. The latest such study involving over 200,000 twins followed across 32 years is revealing more of the story.
Nature or Nurture
The researchers analysed data taken from identical and fraternal twins from the Nordic countries of Denmark, Finland, Norway, and Sweden. They discovered around 33% of cancer incidence was strongly influenced by genetics, but this figure varied wildly depending on the type of cancer involved. Cancers of the skin, ovary, kidney, breast, prostate and uterus were the most genetically linked.
“Earlier studies were not critically large enough to be able to provide any information about heritability for [some] cancers. Our ability to provide information about the relative contribution of genetic factors for these more rare cancers is really important”
What does heritability mean?
The term is very confusing and refers to the extent genetic differences can account for cancer figures. It does not mean a cancer was a case of genetics over environment and because of that, this data is still somewhat obscure. It found a significant pattern of familial risk, but while significant, it's perhaps less than you might predict.
The study did not address the difference between hereditary risk and heritability, as it focused on the variance in cancer risk dependent on individual genetic differences. It did not measure how likely a cancer was to repeat down the generations.
So where are we now?
Cancer is complicated, and this study reinforces that...yet again. It's clear there are a number of genetic components that make specific cancer far more risky, but that developing cancer is far from certain even with this added risk. What information like this is useful for however, is in combination with precision medicine tactics. If we can establish specific gene variants behind significant heritability, then we can perhaps offer tailored advice for those more at risk.
“I think it would be unconscionable and completely unjustified at this point to try to translate the results of a finding like this into risk or probability that a physician would tell a patient”
Read more at Stat News