The January 2 edition of the journal Science was led by researchers at Johns Hopkins University in the USA, and based on a statistical model that includes many types of cancer in a range of human tissues. Its conclusion was that cancer is often caused by the “bad luck” of random mutations that arise when cells divide, not family history or environmental causes.
However, it did not include breast cancer, which is the most common cancer in women, or skin cancer which is the most common cancer in men, followed by prostate cancer.
In the adult cancers they did measure (and not a very comprehensive list either), about two-thirds of these could be explained by random mutation in genes that encourage tumors to grow, while the remaining one third was due to environmental factors and inherited genes.
“This study shows that you can add to your risk of getting cancers by smoking or other poor lifestyle factors,” said study author Bert Vogelstein, a professor of oncology at the Johns Hopkins University School of Medicine.
“However, many forms of cancer are due largely to the bad luck of acquiring a mutation in a cancer driver gene regardless of lifestyle and heredity factors.”
He added that people who live a long time without getting cancer, despite being long-time smokers or being exposed heavily to the sun, do not have “good genes.” “The truth is that most of them simply had good luck,” he added.
Now, don’t get me wrong, Johns Hopkins is a well known and respected university, but this study, as reported in Science January 2, is not well enough documented. How many cancers did they study? Especially having excluded the major cancers, how many were left? To my simple mind, looking at a small percentage of the whole and drawing conclusions from it is risky to say the least.
They reported that the team sought to look at cancer in a new light, by searching the scientific literature for information on how many times stem cells divided over the course of an average person’s lifespan.
This process of self-renewal occurs naturally in the body and helps repopulate cells that die off in a specific organ. However, I would point out that this self-renewal is not 100 percent, otherwise we would all live for ever as there would be no kidney disease, for example, as all you have to do is sit tight and wait for spontaneous cell renewal.
They also claim that researchers have long understood that cancer can arise when stem cells make random mistakes, known as mutations. (Note the use of “can” arise and not “will” arise.)
But the study represents the first attempt at comparing how many cancers arise from this process, compared to family history or environmental factors.
Some 22 cancer types arising in 31 tissues studied could be traced back to random mutations, the study found.
The other nine “had incidences higher than predicted by ‘bad luck’ and were presumably due to a combination of bad luck plus environmental or inherited factors,” the university said.
These nine types included lung cancer and skin cancer – which are influenced by exposure to smoke and sunshine – as well as some cancers known to be hereditary.
The findings mean that an even greater emphasis should be placed on early detection of cancer and research that could detect these harmful random acts before they lead to widespread cancer.
“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,” said biomathematician Cristian Tomasetti, an assistant professor of oncology at the Johns Hopkins University School of Medicine and Bloomberg School of Public Health.
“We should focus more resources on finding ways to detect such cancers at early, curable stages.” Breast and prostate cancers were not included in the study because the literature did not show reliable stem cell division rates in those areas of the body, the authors said.
So, because these major cancers did not fit in with their study, they left them out.
But I do agree with the concept of early detection to get the development of cancer at the early stages.
