INTRODUCTION
Skin cancer is the most common form of cancer in the United States. According to the World Health Organization, the incidence of both nonmelanoma and melanoma skin cancers has increased over the past few decades. Skin cancer rates seem to be climbing rapidly in the US population.1 In the United States, the incidence substantially increased from 1992 through 2006, and is now about double the last published estimate from 1994.2 Currently, between 2 and 3 million nonmelanoma skin cancers (NMSCs) and 132,000 melanoma skin cancers occur in the United States each year.1
Although skin cancers can develop without precursors, there are clearly certain skin lesions that may give rise to malignancies. Actinic keratosis (AK) is the most common precancerous lesion, which affects more than 58 million Americans.3 People with a fair complexion, blond or red hair, and blue, green, or gray eyes have a high likelihood of developing one or more of these common precancers.4
Chronic exposure to ultraviolet (UV) radiation is known as the most important risk factor for the development of AK and squamous cell carcinoma (SCC).5 It is not uncommon for a patient who has had a previous skin cancer to present with new AK lesions or even skin cancers. A study from the University of Vermont showed that of patients who had previously had NMSC treated in their clinic, 39% returned with a new NMSC lesion in a different location within 2 years.6 It is well-known and clear that individuals who were previously treated for skin cancer must be vigilant about new lesions—both precancerous and cancerous. In 2009, Criscione and colleagues conducted a study examining the progression of AK to SCC and basal cell carcinoma (BCC).7 The study involved the examination of 7,784 AKs in a high-risk population and found that nearly 65% of primary SCCs and 36% of primary BCCs arise from clinically diagnosed AK.7 DNA analysis of the cells within AK shows characteristic UV-induced mutations in key genes, including TP53 and deletion of the gene coding for the p16 tumor suppressor protein.8-10 In both histologic and molecular parameters, AK shares features with SCC.11
UV protection is the cornerstone in post–skin cancer topical skin care. The American Academy of Dermatology emphasizes the importance of applying a sunscreen with a sun protection factor of at least 30 to every exposed part of skin at least 20 minutes before going outdoors.3 In addition, careful monitoring by a dermatologist following treatment is critical. At the same time, self-examination and routine check-ups with a dermatologist are important not only for those with a history of skin cancer, but all patients. Early detection and treatment of skin cancer leads to the best outcomes for these patients. In addition to protection, avoiding the progression of precancerous lesions can also be a critical area of viable intervention. The objective of this article is to review studies about cosmeceuticals that can be used by people who have had skin cancer previously and may work, in some way, to help prevent the formation of new skin cancer lesions
CAFFEINE
The usefulness of topical caffeine and its derivatives for skin care is generally based on anti-inflammatory properties created by the presence of antioxidants. It is proposed that the antioxidative properties of caffeine reduce irritation and red-
