Few days ago, Science published a groundbreaking research by Tomasetti and Vogelstein from Johns Hopkins University, hinting how getting cancer is significantly a matter of bad luck (*). The authors focus on stem cells and their divisions, and by applying some statistics, show that there is a strong correlation between such repeated process and the development of cancer. But let's go with order.
Stem cells and cancer
Stem cells are defined through three properties: (1) they can regenerate and repair themselves, (2) they are unspecialised but (3) can generate specialised cells. Even though stem cells are relatively few in all tissues (**), they play the very important role of "repairing" organs. During such process of division, there is a chance something goes wrong and a defective cell is generated.
Tomasetti - Vogelstein's study
The authors prove for many organs that there is a strong correlation (Spearman's rho 0.81) between number of stem cells divisions and lifetime risk. To underline the result, they show the following example:
For example, patients with FAP (familial adenomatous polyposis, Ed.) are ~30 times as likely to develop colorectal cancer than duodenal cancer [...]. Our data suggest that this is because there are ~150 times as many stem cell divisions in the colon as in the duodenum. The lifetime risk of colorectal cancer would be very low, even in the presence of an underlying APC gene mutation, if colonic epithelial stem cells were not constantly dividing. A related point is that mice with inherited APC mutations display the opposite pattern: small intestinal tumors are more common than large intestinal tumors. Our analysis provides a plausible explanation for this striking difference between mice and men; namely, in mice the small intestine undergoes more stem cell divisions than the large intestine [...].
Consequences
If further investigation confirmed this study, early diagnosis of cancer would result fundamental to save people's lives. As I discussed previously in the case of breast cancer, X-rays used in CT scans are considered one of the environmental factors causing cancer. Early diagnosis may translate into relatively frequent scans, hence low radiation dose becomes a central issue. The research group I participate in, develops algorithms to reproduce nice imaging outcomes with few measurement data (that is, lower radiation doses).
I really hope to read soon updates on this exciting research!
(*) To check other sources about the study: Time, The Guardian,
(**) Tomasetti and Vogelstein collected such datas in this appendix.
Featured image is courtesy of The Telegraph.
I would like to make a clarification, after several critics to the paper and how the press reported it.
This study does not tell you the cancer is mostly about bad luck, but that some data - limited to American population and some kinds of cancer - show a correlation between stem cell duplication ("bad luck") and chance of getting some type of cancer. This is a PRELIMINARY study that says "Hey, there could be something interesting here, let's research more about it".
It is wrong both to overstate this result and spread bad information, but as a scientist I say it's also wrong to diminish this result just because of viral bad press. I sincerely hope there will be further investigation about this matter.
http://news.sciencemag.org/biology/2015/01/bad-luck-and-cancer-science-reporter-s-reflections-controversial-story