What causes most cancers?

What causes most cancers?

When it comes to cancer, many people ask themselves “why me?” or “why my family member?” While cancers are a result of many factors, new research looked to identify the most common cause.

The research, out of Johns Hopkins University, used mathematical modeling to look at mutations that lead to abnormal cell growth for 32 different types of cancer. They found that many tumors were actually caused by random genetic “mistakes.” The researchers from the study, which was published in the journal Science this month, said they now believe that the majority of cancers are in fact caused by these random copying errors.

“It is well-known that we must avoid environmental factors such as smoking to decrease our risk of getting cancer. But it is not as well-known that each time a normal cell divides and copies its DNA to produce two new cells, it makes multiple mistakes,” said study co-author Cristian Tomasetti in a news release. “These copying mistakes are a potent source of cancer mutations that historically have been scientifically undervalued, and this new work provides the first estimate of the fraction of mutations caused by these mistakes.”

As part of their mathematical model, they found, for example, that when all these mutations are added up, 77 percent of pancreatic cancers are due to the random errors. For other cancers, the random copying errors were even more prevalent. For prostate cancer and bone cancer, over 95 percent of the mutations were caused by the copying problems.

Still not all cancers followed this pattern. Sixty-five percent of lung cancer mutations were due to environmental factors and only 35 percent due to copying errors.

Overall, they found 66 percent of the mutations could be attributed to copying errors.

Experts aren’t surprised by these results.

“As an oncologist and researcher myself, the results of this study were not surprising but rather educating on something we all felt to be true for a long time,” says  Dr. Sigrun Hallmeyer, an oncologist-hematologist at Advocate Lutheran General Hospital in Park Ridge, Ill. “There is an important key message here that most cancers arise ‘spontaneously’ due to random copy errors, and even in the very best human environment and adherence to lifestyle guidelines, cannot be avoided.”

Still, Dr. Hallmeyer doesn’t believe this should be the key takeaway.

“A small minority of cancers are due to exposure – for instance, smoking – and an even smaller fraction due to inherited factors. This means that many of us will not be able to influence our fate of getting cancer; however, the take home message is that one can reduce your chance by a significant percentage when leading a healthy life. The rest of the risk can be modified by participating in early screenings and regular doctor visits, which can aid in detecting many cancers in an early and often curable state.”

So the main message: focus on what you can do to reduce your risk, not what you can’t control.

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  1. You mostly depict young people in all of your photos. This seems to inflict a sense of disingenuousness and commercial marketing on your site.

  2. This is interesting information, however, there are many documented cases that people with various cancers have cured/put it into remission by changing their diet. So, I disagree with the article that states, “This means that many of us will not be able to influence our fate of getting cancer; however, the take home message is that one can reduce your chance by a significant percentage when leading a healthy life.” Well, wait…on the one hand you’re saying you can’t change your fate, but then at the end of the sentence you are saying that by leading a healthy lifestyle you can reduce your risk significantly??? I’m sorry, but let’s tell it like it is…cutting out sugar, gluten, smoking & integrating clean eating (mostly veggies…high greens, fruits, non-gmo grains, non-packaged foods) plus exercise will not only help you avoid cancers & other diseases, but can cure or dramatically reduce the way they affect the body. Although this article may shed some light on some cases, the majority are preventable by lifestyle changes. It’s not all genetic math…it’s what you decide to put in your body.

  3. because I am not a doctor. I found this article very confusing… What are copying errors . not really a clear article.

    • Copying your unique DNA. It appears when this happens to make a new cell, an error in the exact DNA copy could have mistakes in the transfer.

  4. Yes, I was trying to read carefully as JB was, as a layman. I follow it mostly, but the article and the mention of copying raises my question: I figure this concept of copying is also what we call “growth”–cell division.
    A LOT of this happens before birth, of course, and also we associate it with childhood. Why then is the appearance of cancer something we associate more with old age, than with childhood when most of the growth (and I would assume, the “copying”) occurs? Cancer is not unknown in childhood, but mathematically, according to the article, wouldn’t the likelihood of cancer be greater in childhood, with all the cell division and copying going on at a higher rate than in “old age?”
    Also, I wonder whether the human body has any kind of protective response against these mutations.
    And BTW, Eric’s comments seem to be turning a deaf ear to the research and comments included in the article, and he’s just writing his own article according to his own beliefs. Sounds like he’s trying to turn the info around, and profess the opposite.

  5. Aren’t the random copying errors, to some extent, influenced by various forms of radiation and environmental toxins, that we breathe in and ingest? If so, we do have the ability to avoid copying error cancers to some degree.

About the Author

Jackie Hughes
Jackie Hughes

Jacqueline Hughes is a former manager, media relations at Advocate Aurora Health. Previously, she was the public affairs and marketing manager at Advocate Lutheran General Hospital in Park Ridge, IL. She earned her BA in psychology at Stanford University in Palo Alto, California. Jackie has 10 plus years experience working in television and media and most recently worked at NBC 5 in Chicago. In her free time, she enjoys swimming, going to the movies and spending time with her family.