diagnosis is necessary. it is a rarely utilized technique for ak treatment. shave excision and curettage (sometimes followed by electrodesiccation when deemed appropriate by the physician): this technique is often used for treatment of aks, and particularly for lesions appearing more similar to squamous cell carcinoma, or those that are unresponsive to other treatments. the surface of the lesion can be scraped away using a scalpel, or the base can be removed with a curette. tissue can be evaluated histopathologically under the microscope, but specimens acquired using this technique are not often adequate to determine whether a lesion is invasive or intraepidermal. dermabrasion: dermabrasion is useful in the treatment of large areas with multiple ak lesions. the process involves using a hand-held instrument to "sand" the skin, removing the stratum corneum layer of the epidermis. diamond fraises or wire brushes revolving at high speeds are used. the procedure can be quite painful and requires procedural sedation and anesthetic, necessitating a hospital stay. one-year clearance rates with dermabrasion treatment are as high as 96%, but diminish drastically to 54% at five years. laser therapy laser therapy using carbon dioxide (co2) or erbium:yttrium aluminum garnet (er:yag) lasers is a treatment approach being utilized with increased frequency, and sometimes in conjunction with computer scanning technology. laser therapy has not been extensively studied, but current evidence suggests it may be effective in cases involving multiple aks refractive to medical therapy, or aks located in cosmetically sensitive locations such as the face. the co2 laser has been recommended for extensive actinic cheilitis that has not responded to 5-fu. chemical peels a chemical peel is a topically applied agent that wounds the outermost layer of the skin, promoting organized repair, exfoliation, and eventually the development of smooth and rejuvenated skin. multiple therapies have been studied. a medium-depth peel may effectively treat multiple non-hyperkeratotic aks. it can be achieved with 35% to 50% trichloroacetic acid (tca) alone or at 35% in combination with jessner's solution in a once-daily application for a minimum of 3 weeks; 70% glycolic acid (α-hydroxy acid); or solid co2. when compared to treatment with 5-fu, chemical peels have demonstrated similar efficacy and increased ease of use with similar morbidity. chemical peels must be performed in a controlled clinic environment and are recommended only for individuals who are able to comply with follow-up precautions, including avoidance of sun exposure. furthermore, they should be avoided in individuals with a history of hsv infection or keloids, and in those who are immunosuppressed or who are taking photosensitizing medications. prognosis squamous cell carcinoma of the nose. this skin cancer can develop from actinic keratoses if they are not treated. untreated aks follow one of three paths: they can either persist as aks, regress, or progress to invasive skin cancer, as ak lesions are considered to be on the same continuum with squamous cell carcinoma (scc). ak lesions that regress also have the potential to recur. progression: the overall risk of an ak turning into invasive cancer is low. in average-risk individuals, likelihood of an ak lesion progressing to scc is less than 1% per year. despite this low rate of progression, studies suggest that a full 60% of sccs arise from pre-existing aks, reinforcing the idea that these lesions are closely related. regression: reported regression rates for single ak lesions have ranged between 15 and 63% after one year. recurrence: recurrence rates after 1 year for single ak lesions that have regressed range between 15 and 53%. clinical course given the aforementioned differering clinical outcomes, it is difficult to predict the clinical course of any given actinic keratosis. ak lesions may also come and go—in a cycle of appearing on the skin, remaining for months, and then disappearing. often they will reappear in a few weeks or months, particularly after unprotected sun exposure. left untreated, there is a chance that the lesion will advance to become invasive. although it is difficult to predict whether an ak will advance to become squamous cell carcinoma, it has been noted that squamous cell carcinomas originate in lesions formerly diagnosed as aks with frequencies reported between 65 and 97%. epidemiology actinic keratosis is very common, with an estimated 14% of dermatology visits related to aks. it is seen more often in fair-skinned individuals, and rates vary with geographical location and age. other factors such as exposure to ultraviolet (uv) radiation, certain phenotypic features, and immunosuppression can also contribute to the development of aks. men are more likely to develop ak than women, and the risk of developing ak lesions increases with age. these findings have been observed in multiple studies, with numbers from one study suggesting that approximately 5% of women ages 20–29 develop ak compared to 68% of women ages 60–69, and 10% of men ages 20–29 develop ak compared to 79% of men ages 60–69. geography seems to play a role in the sense that individuals living in locations where they are exposed to more uv radiation throughout their lifetime have a significantly higher risk of developing ak. much of the literature on ak comes from australia, where the prevalence of ak is estimated at 40–50% in adults over 40, as compared to the united states and europe, where prevalence is estimated at under 11–38% in adults. one study found that those who immigrated to australia after age 20 had fewer aks than native australians in all age groups. research diagnostically, researchers are investigating the role of novel biomarkers to assist in determining which aks are more likely to develop into cutaneous or metastatic scc. upregulation of matrix metalloproteinases (mmp) is seen in many different types of cancers, and the expression and production of mmp-7 in particular has been found to be elevated in scc specifically. the role of serin peptidase inhibitors (serpins) is also being investigated. serpina1 was found to be elevated in the keratinocytes of scc cell lines, and serpina1 upregulation was correlated with scc tumor progression in vivo. further investigation into specific biomarkers could help providers better assess prognosis and determine best treatment approaches for particular lesions. in terms of treatment, a number of medications are being studied. resiquimod is a tlr 7/8 agonist that works similarly to imiquimod, but is 10 to 100 times more potent; when used to treat ak lesions, complete response rates have range from 40 to 74%. afamelanotide is a drug that induces the production of melanin by melanocytes to act as a protective factor against uvb radiation. it is being studied to determine its efficacy in preventing aks in organ transplant patients who are on immunosuppressive therapy. epidermal growth factor receptor (egfr) inhibitors such as gefitinib, and anti-egfr antibodies such as cetuximab are used in the treatment of various types of cancers, and are currently being investigated for potential use in the treatment and prevention of aks.