Why Not Have a Cigarette?

Hmm. Besides not smelling too good and giving me an asthma attack, cigarettes are scary. I went to a seminar today on "molecular profiling" of lung cancer and was rather surprised by the statistics. I wrote my thesis on breast cancer, and am currently learning the ropes on brain cancer, but as far as lung was concerned, I figured it was an epithelial cell derived neoplasm, so how different could it be?

I was surprised that while lung cancer caused by smoking is so easily preventable, lung cancer ranked in the top four of the most commonly occurring neoplasms. Of these four, it had an alarmingly low 5-year survival ratio -- only ~18%, while the other three top offenders had ratios of 60-90%. Yeesh. When I went to the website of the Canadian Cancer Society to see why there was such a large discrepancy, it seems that early detection of the disease, allowing early intervention, just didn't seem to be happening, as the symptoms seem to develop slowly.

The take home message: If you're going to get some form of cancer, lung cancer is not a good one to get.

As I browsed further through the information provided by the CCS, the list of health problems that could be caused by smoking became more extensive, and the risk of other cancers also increased.

One of the most frightening things, is that mutations caused by smoking can apparently be passed on to children through sperm.










Cigarette smoke contains chemicals that mutate the p53 gene, resulting in a non-functional protein. p53 is a tumour suppressor protein, which means that it normally stops cells that have DNA damage from dividing (and continually dividing in an uncontrolled manner until a tumour forms). This "lock down" of the cell is not lifted until the cell either manages to repair the damaged DNA, so that it can function normally, or a self-destruct program is initiated (apoptosis) so that the damaged cell is destroyed before a tumour can form.

As you may well surmise, if p53 cannot function, cells that have DNA damage will not be stopped from dividing and spreading through the body. Unlike the X-Men, these mutated cells have no idea what they are supposed to be doing, and end up disrupting the function of other tissues and organs, which is why cancer is so devastating.

http://www.cancerci.com/content/5/1/10/figure/F2

I am, of course, over-simplifying things to make a point without getting lost in the details: smoking just isn't worth it.