Recovery from sun damage
Dear OncoLink "Ask The Experts,"
I was at the Penn melanoma conference and Dr. Elenitsas showed two slides of the dermis. One was damaged by the sun, and the other one did not have sun damage. My question is: does the dermis have the ability to recover from the damage of the sun? For instance, I have practiced safe sun habits for 5 years: protective clothing and sunscreen. Unfortunately, before that time, I was a sun worshiper (I am now in my 40's); does that mean it is too late for my skin to recover?
Thank you for your time.
Keith T. Flaherty, MD, Assistant Professor of Medicine (Hematology/Oncology), responds:
The damage that sun causes to the deep layer of the skin (the dermis) is cumulative over the course of one's life. The term ?solar elastosis? is used to describe the appearance of these changes when a skin biopsy is examined under the microscope. The severity of these changes is clearly related to sun exposure reported by patients who have had these biopsies. So, there is general agreement that a pathologist can determine the accumulated sun damage in a skin biopsy. Having said that, it is often possible for a dermatologist to determine the extent of sun-induced damage by a simple office examination. There are certain non-cancerous skin growths that are closely related to the total amount of sun exposure, particularly actinic keratoses.
With regards to the risk of developing skin cancers, such as squamous cell carcinoma and basal cell carcinoma, there is a very clear relationship between the total amount of sun-induced damage and the risk of these cancers. So, every increment in sun-induced damage is associated with an increase in the risk of these cancers. Therefore, safe sun habits will benefit you in relation to these cancers and things like actinic keratoses.
For melanoma, the relationship is a bit more complicated. For some people, it is clear that this same type of relationship exists. For those people, avoiding future sun damage will likely reduce the risk of developing melanoma. However, there are several studies which show that a history of severe sunburn early in life (childhood or teenage years) may be a more important risk factor for melanoma than total sun exposure over the course of one's life. That data suggests that, for some people, the damage is done early, and avoiding sun exposure later in life may not substantially reduce the risk of melanoma. The real problem in counseling people about sun exposure is that we don't know how to determine who the people are for whom life-long sun exposure is more important and who the people are for whom severe exposure early in life is more important. So, we advise parents to protect their children from severe sunburns, and we advise all adults to minimize their cumulative sun exposure.
It is safe to say that all skin cancers (taken together) will be reduced my minimizing lifelong sun-induce skin damage. For melanoma, the connection between early severe burns, cumulative sun-induced skin damage, and melanoma is less clear. It is likely the case that certain genetic factors determine the risk of melanoma for each type of sun exposure. Melanoma researchers are trying to learn what those factors are so that people who are at very high risk can be targeted for prevention.