Debbie Knight

Posts Tagged ‘cancer’

Science news stories need better context

In observation on April 19, 2012 at 9:00 am

I’m taking a science communication class this quarter. And one of my fellow students, a communication major, contributed the following to our class discussion:

“It only takes one gene to cause lung cancer. One day you’re smoking a cigarette when you’re 25 (years old), and one gene flips over and you’ve got lung cancer. It only takes one.”

It’s not quite that simple…

I didn’t say anything to correct him during the class discussion — but maybe I should have.

And it took me a while to realize how he might have arrived at this oversimplified and somewhat  inaccurate conclusion.

News stories often report that scientists have discovered yet another gene associated with some form of cancer. Important information to relay, but without the proper context, a reader could think that it only takes that one particular gene with a single mutation to cause cancer when in reality it’s an accumulation of changes in the cell’s genome.

And it’s complicated.

Scientists still think it takes multiple assaults to a cell (especially to the DNA) before that cell becomes cancerous. Each of those assaults can cause a small change which by itself has little if any affect on the cell.  But those assaults start to add up (like cars in a multiple-car accident) and the chaos that is cancer can ensue.

The assaults can be many things (chemicals, sunlight and radiation exposure come immediately to mind). And those assaults can affect the cell in a variety of ways. It can affect the DNA, how it’s expressed, how the gene product interacts with other gene products, etc. A mutation in the DNA which changes one letter in the string of letters of a gene could change the way the blueprint is interpreted into a protein. The addition of a group of atoms (like a methyl group, for example) can interrupt where the blueprint-reading machinery hooks up to the gene’s promoter changing how that gene is expressed. Some assaults affect the proteins made from those genes. If a protein is made wrong it can change how a signal is transmitted from outside the cell to inside the cell. But not all involve an actual gene — it can occur in the DNA sequences between the genes. Pieces of DNA can switch places with other pieces of DNA which can occur within a single chromosome or between two chromosomes. And with the discovery of micro-RNAs, things have gotten that much more complicated.

Pretty much anywhere there is some form of cellular control there is vulnerability.  And the list is extensive.

A person can even inherit DNA from his parents that has a few of these changes already on board. This means that although these inherited changes may not cause the disease, it may take fewer assaults for this individual to develop cancer.

For example, a woman may inherit a mutation in her BRCA1 gene that puts her at higher risk of developing breast cancer but that doesn’t mean as soon as she’s born or hits puberty that she will have breast cancer. It may take a few more DNA changes before a cell rages out of control to become full-blown breast cancer. On the other hand, there is a possibility, based on the rest of her genome, that the woman may never develop breast cancer in her lifetime.

As I said, it’s complicated.

So, the student was not entirely right when he said it only takes one gene to be “flipped over.”

It is a single step (in a series of steps) in the making of a cancer cell.

And it doesn’t stop once a cancer cell has finally lost control of itself. More assaults, more mutations, more changes can make the cancer cell grow faster, help it dodge the immune system or help it escape to other places in the body.

I realize that in a news story there is limited time and space to discuss all the angles, but an effort should be made to include perhaps a tiny paragraph that places the discovery and the risk in  proper context.

A few well-placed words could prevent a misconception like this student had.


Additional reading:

Baudot A., de la Torre V., and Valencia A. Mutated genes, pathways and processes in tumours. EMBO Rep. 2010 October; 11(10): 805–810

Stratton S.R., Campbell P.J., and Futreal P.A.  The cancer genome. Nature. 2009 April 9; 458(7239): 719.