How does Basal Cell Carcinoma Originate in the Skin?
We’ve heard about sunburns and sunscreen, fair complexions and temperate climates, but this does not explain how these risks lead to the development of basal cell carcinoma in the skin.
“It’s not as big of a black box as it used to be,” says Dr. Adam Mamelak, skin cancer specialist and Mohs micrographic surgeon in Austin, Texas. “In fact, years of research have taught us a lot of how these risk factors lead to actual the development of skin cancer.” After performing laboratory bench research on skin cancer during his years as a Research Fellow at Johns Hopkins University, Dr. Mamelak says there are some basic things that are known about these tumors.
Where in the skin do Basal Cell Carcinoma Develop?
“There is a strong relationship between basal cell carcinoma and hair follicles,” explains Dr. Mamelak. “We do not tend to see these tumors developing on non-hair bearing skin.” Dr. Mamelak notes that it is exceedingly rare to find basal cell carcinomas developing on the palms or soles (squamous cell carcinoma is more common in these areas). Even when these cancers involve the lips, there is usually some involvement of the skin just adjacent to the mouth.
There are actually stem cells in the skin and hair follicles that continuously grow and recycle. It is because of these cells that our hair continues to grow, and our sweat glands continue to work over our lifetime. One theory suggests that basal cell carcinoma arises from these pluripotential cells in hair follicles and the skin.
What about UV?
Ultraviolet radiation has been found to damage DNA in skin cells. These mutations are thought to induce the expression and turn on cancer causing genes (the so-called proto-oncogenes) in the cells. Furthermore, by mutating the DNA, they allow the skin cells to continue to grow and proliferate.
“There is actually a very specific molecular signaling pathway in skin cells than has been implicated in the development of Basal Cell Carcinoma,” says Dr. Mamelak. This pathway is called Sonic Hedgehog (yes, named after the video game!). UV-induced mutations have been noted in Sonic Hedgehog in a large and consistent number of Basal Cell Carcinoma. It is for this reason that a new Sonic Hedgehog inhibiting medication (Erivedge) has been developed for the treatment of some of these skin tumors.
UV light has also been shown to suppress the body’s immune system in the skin. “This is why UV phototherapy is used for psoriasis and eczema, skin diseases characterized by too much inflammation or an overactive immune response in the skin,” explains Dr. Mamelak. However, in prolonged doses of UV radiation or chronic sun exposure, this immune suppression in the skin can decrease the body’s ability to detect and fight off cancerous cells (aka tumor surveillance). This could lead to the growth of skin cancers like basal cell carcinoma, or even melanoma.
If you have been diagnosed with Basal Cell Carcinoma, or have questions about skin cancer treatment, please contact Sanova Dermatology today. Our board-certified dermatologists possess the knowledge and skills to help you with all of your skin care needs.