The Other 97 Percent of Skin Cancers

Squamous cell skin cancer and smoking link meta-analysis

(RxWiki News) When you mention skin cancer, most people think of melanoma. But surprisingly, 97 percent of skin cancers look completely different than melanoma. As you may have already guessed, they are a lot more common.

Basal cell carcinoma and squamous cell carcinoma can look more like wounds than warts.

Just like melanoma though, too much sun is the biggest preventable risk factor, and the cancers usually appear in exposed areas of the body. 

"Ask your doctor for help in quitting smoking."

A big picture research overview by Jo Leonardi-Bee, PhD, who works for the UK Centre for Tobacco Control Studies, took all the available data from 23 separate studies on skin cancer and found that there was a 52 percent increase in risk for squamous cell carcinoma in smokers.

On the other hand, her analysis of the data was unable to find any link between increased risk for basal cell carcinoma and smoking.

Some theories previously proposed to explain the increased squamous cell skin cancer risk in smokers include the antioxidant theory, where the human body uses up its chemical resources on the toxins from the tobacco smoke, leaving it unable to effectively repair the damage from UV radiation.

This argument is difficult to prove when there is no increased risk for basal cell skin cancer, leaving some scientists to consider that the tobacco smoke might directly irritate the outer layer of skin.

Squamous cells are the layer of skin cells that you see, and are the most exposed to the sun. Basal cells are a few layers deeper. Studies have shown that on average, squamous cell skin cancer is more aggressive, but basal cell skin cancer is slow to grow and is unlikely to metastasize.

At first glance, it may be hard to tell the type of cancer, so doctors recommend getting a check-up any time you notice unusual areas of skin damage that don't seem to be healing normally.

The documented increase in risk for squamous cell skin cancer this study points out is a correlation between squamous cell skin cancer and smoking. Proving that smoking causes squamous cell skin cancer is a lot more difficult.

For example, somebody might later prove that smokers may generally spend more time outside exposed to the sun, or are less likely to use sunscreen.

While these big meta-analysis studies can be very impressive in terms of raw numbers, it's important to remember in the middle of the avalanche of data that the conclusions from a meta-analysis are only as good as the quality of the data from the weakest study that was included.

Leonardi-Bee used the data from 23 different studies in 11 countries across four continents, so the authors felt comfortable concluding that the observed relationship between smoking and increased risk of developing squamous cell skin cancer was worth considering.

The article was published online on June 18, 2012 in the journal Archives of Dermatology.

Funding for the study was provided by the UK Centre for Tobacco Control Studies.

Reviewed by: 
Review Date: 
June 22, 2012