Researchers find most cancers caused by genetic error
By Emma Gruner, Staff Writer
Every year in the United States, 1.6 million people become infected with cancer, with 600,000 of those cases being fatal. In such conditions, it is only natural to pin the blame on an outside source such as cigarette smoke, or solar radiation, or chemical contaminants in our food and water.
Surely, we say, our own bodies cannot be that faulty. Yet according to a recent study by Johns Hopkins University, they very well could be. The study, published in Science on March 23, claims that two-thirds of cancer-causing mutations stem not from genetic or environmental factors, but by random errors in cell division.
The basis for this study assumes three different causes of cancer-causing mutations. The first is heredity, or mutated genes that have been passed down from a parent.
This is the rarest variety of mutations, accounting for only five percent of the total. The second is the environment, or, more specifically, factors such as smoking, diet, exercise, sun exposure and chemical exposure.
Such environmental hazards are traditionally given a lot of weight in cancer-prevention discussions, yet they are only responsible for 29 percent of all cancer-causing mutations. The final cause, which, according to the study, 66 percent of these mutations can be attributed to, is essentially chance.
As our cells divide and replicate their genes, random mistakes are made constantly. While these mistakes are usually harmless, their occurrence in cancer-driving genes alongside other mutations can ultimately lead to a diagnosable illness.
The study was conducted by Drs. Bert Vogelstein and Cristian Tomasetti, both of the Kimmel Cancer Center at Johns Hopkins. Their work was originally published in 2015, but received considerable criticism from the scientific community.
Many scientists claimed the team had misunderstood their data, and that their work was undercutting important messages about cancer preventive measures.
Over the next two years, though, Vogelstein and Tomasetti double-checked their figures, linked them with other studies on specific types of cancer, compared them to data from 69 countries, and ultimately came to the same conclusions.
Of course, these new results certainly do not downplay the importance of a healthy lifestyle in the fight against cancer.
Most cancers stem from a combination of the three mutation causes, and multiple mutations would need to be present for the cancer to progress. Also, the factor of chance has a higher influence in some cancers than others.
Pediatric cancers, as well as cancers of the brain and colon, have the highest input from random mutation.
Other cancers have a much larger environmental factor. Lung cancer is a prime example due to the damage caused by smoking, asbestos and radon gas. Even with the new study, a full 40 percent of cancers are preventable if people do not smoke, avoid heavy sun exposure and eat nutritious diets.
According to Vogelstein, “We’re not saying the only thing that determines the seriousness of the cancer, or its aggressiveness, or its likelihood to cause the patient’s death, are these [random] mutations. We’re simply saying that they are necessary to get the cancer.”
In the end, the results of these studies will have a wide variety of implications, both positive and negative. On the serious side, the study puts the “average person” at a much higher risk for cancer than previously thought.
Everyone is susceptible, regardless of family history or lifestyle, and regular screenings, already highly recommended, are now an absolute necessity.
Yet for those already suffering from cancer, the team hopes these findings will bring a sort of relief.
Vogelstein says, “We hope that this research offers comfort to the literally millions of patients who have had cancer but who have lived nearly perfect lifestyles — who have never smoked, who have avoided the sun … who exercise regularly. It’s not your fault. Nothing you did or didn’t do was responsible for your illness.”
Vogelstein continues, “They also hope to bring a similar comfort for the parents of child cancer patients; many such parents blame themselves for their children’s illnesses, even though those illnesses would have occurred no matter what, and “we don’t need to add guilt to an already tragic situation,” he said.
As far as repercussions for future research, the team believes that their findings could turn the search for a cure in a completely new direction.
Despite the influence of the environment, the study suggests that those factors are not the real enemy. Even in a perfect environment in which smoking was banned, industry was nonexistent and everyone ate kale shakes for every meal, human cells would still make mistakes, and cancer would still arise.
“Most of the enemy is inside us. They are already here,” says Vogelstein. He hopes that their findings will attract more attention towards the study of random mutations, and hopefully bring us closer to the idyllic, truly cancer-free society.