We all know that unhealthy lifestyles and genetics increase the risk of developing cancer, but a new study suggests that hereditary or environmental factors are not the primary cause of two-thirds of cancer types. Instead, misfortune plays a large part.
According to the study, published in Science and widely reported on in the media, 65% of adult cancers are mainly due to “bad luck,” or random genetic mistakes that occur during the process of cell division in the body.
“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,” Dr. Bert Vogelstein of the Johns Hopkins University School of Medicine said in a media release.
Cell division is constantly happening in the body to replace old cells. Sometimes genetic mutations occur during the process. As might be expected, the risk of mistakes increases with the increased number of cell divisions. Drs Vogelstein and Cristian Tomasetti, analyzed the total number of stem cell divisions in 31 tissue types during an individual’s lifetime, excluding breast and prostate cancers. They estimated that 22 cancer types were a result of genetic mutations occurring during the normal cell division process and could not be avoided. These include leukemia, pancreatic, bone, ovarian and brain cancers.
“If two-thirds of cancer incidence across tissues is explained by random DNA mutations that occur when stem cells divide, then we should focus more resources on finding ways to detect such cancers at early, curable stages.” said Dr. Tomasetti in a report by The Telegraph carried in the National Post.
According to the researchers, other cancers, such as colorectal, skin and lung cancers are heavily influenced by genes and exposure to cancerous agents, such as smoking for lung cancer, UV exposure for skin cancer and poor diet for colorectal cancer.
Does the new finding mean we should abandon our efforts to prevent cancer? Not at all.
“Everything we know about altering lifestyles to prevent cancer from the environmental point of view we absolutely need to continue doing. If anything our finding puts more stress on the need to spend even more money on early detection,” Dr. Tomasetti told Time magazine.
“About half of all cancers can be prevented through healthy living and healthy public policies,” Gillian Bromfield of the Canadian Cancer Society said in a statement. “We encourage Canadians to lower their risk of cancer by not smoking, eating well, being active, sitting less, maintaining a healthy body weight, limiting alcohol, being safe in the sun and avoiding indoor tanning.”