Researchers have estimated that around 65 percent of variation
in cancer rates between tissue types is related to the number of stem cell
divisions, explaining why cancer occurs more commonly in some parts of the body
researchers, reporting in Science, used data from the scientific literature on stem cell division
rates in 31 different tissue types. They then plotted the total number of stem
cell divisions against the lifetime risk of cancer in each particular tissue
type, revealing a strong correlation between the two.
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,' said study author Professor Bert Vogelstein from Johns Hopkins University School of Medicine.
longevity in people exposed to cancer-causing agents, such as tobacco, is often
attributed to their "good genes" but the truth is that most of them simply had
good luck,' he added.
However, some commentators have criticised the 'bad luck / good
luck' terminology used by the researchers and the media.
Writing on the Cancer Research UK Science Blog, Henry
Scowcroft says: 'According to the researchers, the maths could explain two-thirds of the variation between different
He continues: 'The media coverage has inadvertently jumped
from talking about cancer rates in
different tissues to speculating about cancer
rates in the population.'
Scowcroft also notes that the research only
looked at tissue types for which solid data on stem cell divisions were available, leading to two notable exclusions - breast cancer and prostate cancer - and limiting what we can conclude from the findings.
Additionally, a feature on the NHS Choices website highlights that in the
authors' statistical analyses, the 65 percent figure was not particularly
robust, and the true estimate based on the researchers' data could lie anywhere
between 39 and 81 percent.
In an updated press statement, Professor Vogelstein and co-author Dr Cristian
Tomasetti defended their research findings against criticism that it suggests
that people cannot protect themselves from cancer.
doesn't mean that cancer research should be stalled in any way. Quite the
opposite - our research emphasizes the likelihood that more cancers will appear
in the future simply because aging increases the number of stem cell divisions.
Research on primary and secondary prevention, cancer treatment, and the biology
of the disease is more important than ever.'