They also noted that cells in the large intestine needed to be replaced much more often than in the small intestine.
So there is an apparent correlation between more frequent cell replacement and higher risk of cancer because there are more frequent opportunities for errors to develop in the cells’ genetic code.
In other cases, known environmental factors such as smoking for lung cancer, or sun exposure for skin cancer, can drive up the risk of developing that cancer. Still other cancer risks can be significantly increased by inheriting a known cancer-causing gene.
Tomasetti compared the risk of cancer to the risk of having a car accident. Taking a long car trip increases the risk of being in an accidental car crash — the bad luck example.
Driving a car with defective brakes or driving in snow makes that risk even higher. This correlates to adding a behavior such as smoking or an environmental risk such as sun exposure on top of the “bad luck” factor.
The researchers see their discovery as both good and bad news, depending on your perspective.
Referring to patients who may wonder if they unknowingly did something to bring on their cancer, Tomasetti sees the results as comforting.
Vogelstein believes the report is good news for many people who do not have cancer. While people should still be aware of known behaviors that can increase their cancer risks, they may feel less worried about every action or food choice they make.
But for people who do not have cancer and who prefer to be in control of everything they can, the researchers believe the report will be perceived as bad news and a potential source of fear.
Dr. Kenneth Offit, chief of the clinical genetics service at Memorial Sloan Kettering Cancer Center in Manhattan, said that the hypothesis “appears to be correct”.
But he also noted that not all cancers follow the model in the report. For example, some cancers have a significantly higher hereditary component than the new study suggests.