A new study recently found that two-thirds of cancer cases were mainly caused by DNA mutations in various parts of the body.
These DNA mutations happen during ordinary cell division. A normal cell has a life span and dies out, but is replaced by a new cell via cell division.
Basically, tissues that have more cell divisions increase their chances of random DNA mutations, which increase the cases of some types of cancer. Unlike normal cells, cancer cells do not die and can eventually kill their host.
The researchers studied 31 types of cancer and discovered that 22 types - including pancreatic, bone, testicular, ovarian and brain cancer - were mainly caused by random DNA mutations, noted Reuters.
Nine other types of cancer - including colorectal, skin and lung - were primarily caused by heredity, bad habits and exposure to carcinogens, said the study, which was published in the medical journal Science.
The study didn't include breast and prostate cancer, the biggest killers of women and men, because researchers could not determine reliable cell division rates.
"When someone gets cancer, immediately people want to know why," Dr. Bert Vogelstein, study co-author at the Johns Hopkins University School of Medicine, told Reuters. "They like to believe there's a reason. And the real reason in many cases is not because you didn't behave well or were exposed to some bad environmental influence, it's just because that person was unlucky. It's losing the lottery."
“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. Vogelstein told The Guardian.
Study co-author and Johns Hopkins biomathematician Dr. Cristian Tomasetti added, “If two-thirds of cancer incidence across tissues is explained by random DNA mutations that occur when stem cells divide, then changing our lifestyle and habits will be a huge help in preventing certain cancers, but this may not be as effective for a variety of others."