Despite the scientific community’s long-standing dislike of the concept of “luck”, it seems that randomness is precisely the reason why some people get cancer, while others do not.
According to a group of researchers from the Johns Hopkins Kimmel Cancer Centre in Baltimore, USA, almost two-thirds of all cancer cases may be chalked up to random DNA mutations, which occur during the process of stem cell replication.
Using statistical theory, the scientists demonstrated that the popular idea of “good genes”, supposedly protecting one from cancer regardless of lifestyle choices, is simply wrong.
“All cancers are caused by a combination of bad luck, the environment and heredity, and we’ve created a model that may help quantify how much of these three factors contribute to cancer development,” noted Dr. Bert Vogelstein, professor of oncology at Johns Hopkins University School of Medicine and one of the two authors of the study. “Cancer-free longevity in people exposed to cancer-causing agents, such as tobacco, is often attributed to their “good genes”, but the truth is that most of them simply had good luck.”
The team looked at the literature concerning 31 types of cancer and evaluated whether the number of stem cell divisions, inevitably leading to DNA errors, may be linked to cancer incidence. The results showed that 22 of the 31 different cancer types, including leukaemia, testicular, pancreatic, ovarian, bone and brain cancer were strongly correlated with the number of stem cell divisions in a tissue type.
The remaining 9 cancer types were more heavily influenced by genetic inheritance and environmental factors like carcinogen exposure. “We found that the types of cancer that had higher risk than predicted by the number of stem cell divisions were precisely the ones you’d expect, including lung cancer, which is linked to smoking, skin cancer, linked to sun exposure and forms of cancers associated with hereditary syndromes,” said Dr. Vogelstein.
Overall, the team attributed 65 per cent of all cancers to random mutations and the remaining 35 per cent to the combination of random mutations and genetic and environmental factors.
Dr. Cristian Tomasetti, a biomathematician from Johns Hopkins University and co-author of the study, claimed their work shows that changing one’s lifestyle and habits may help decrease the chance of getting certain forms of cancer, while leaving others largely unaffected.
“Thus we should focus more research and resources on finding ways to detect such cancers at early, curable stages”.
Vogelstein and Tomasetti claim that the reason why they omitted certain common cancers, such as breast and prostate cancer, was the lack of reliable stem cell division rates for them.
Their findings were published in the journal Science on the 2nd of January 2015.