PREVENTATIVE MEDICINE
Skin Cancer Prevention By Fatima Raza OMS-III, Faraz Yousefian, DO and Daniel Fischer, DO
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kin cancer is the most common cancer in the United States, followed by lung cancer, prostate cancer and breast cancer. According to American Academy of Dermatology estimates, one in five Americans will develop skin cancer in their lifetime, and approximately 9,500 people in the United States are diagnosed with skin cancer every day.1 In Texas, the odds are even more grim: the state ranks third in the nation for incidence of malignant melanoma, with 5,020 cases projected to be diagnosed in 2022.2 In the United States, skin cancer represents 20-30% of all neoplasms in Caucasians, 2-4% in Asians and 1-2% in the Black population.3 Of the types of skin cancer, non-melanomatous skin cancers (NMSCs), namely basal and squamous cell carcinomas, are the most commonly diagnosed.4 Both of these cancers have overlapping risk factors, including tanning bed usage and ionizing radiation. However, the most significant risk factor is UV radiation, principally UVB radiation from sunlight exposure. In particular, occupational UVB exposure, as in the agricultural and construction industries, is a major risk factor as compared to nonoccupational risk factors. UVB radiation is thought to be more carcinogenic than UVA radiation due to its complete absorbance by skin and resultant increased ability to mutate tumor suppressor genes. Of the tumor suppressor mutations resulting in skin cancer, p53 is the most common, with mutations found in up to 50% of basal cell carcinomas.4 While the risk factors and pathogenesis of skin cancers are well studied, there remains no consensus on screening guidelines for skin cancer. The USPTF has not published screening recommendations, citing insufficient evidence for its benefit.5 Diagnosis of skin cancers is therefore heavily reliant on clinical examination of the skin lesion. Clinical diagnosis of NMSCs commonly includes aspects of patient history, including raised lesions which bleed and crust. Dermatoscopic evaluation and biopsy can often aid with clinical diagnosis. In melanomatous disease, the importance of early clinical recognition and diagnosis is paramount, as the cancer grows first horizontally and then vertically in stages, with stage correlating to depth. In 1985, researchers at NYU implemented the acronym ABCD, now commonly used in practice − A (asymmetry), B (border irregularity), C (color variegation), D (diameter >6mm) and E (evolving or changing) for clinical diagnosis of melanoma.6 18
SAN ANTONIO MEDICINE • June 2022
In the absence of routine screening, preventive measures become all the more important. The American Academy of Dermatology has published multiple guidelines regarding skin cancer prevention: seeking shade particularly between the hours of 10 am and 2 pm, wearing sunprotective clothing and using broad-spectrum, water-resistant sunscreen with SPF 30 or higher, reapplying every two hours. The AAD additionally recommends regular skin self-exams to detect cancer early.7 In short, these guidelines essentially encourage patients to become their own healthcare advocates. Perhaps the bedrock of skin cancer prevention is the regular use of sunscreen. While most of the population may at least be aware that sunscreen is protective in some form, the wide varieties and types of sunscreens may overwhelm the common consumer. Sunscreens are largely organized into two categories based on active ingredients: organic (physical) and inorganic (chemical). Organic filters include active ingredients such as oxybenzone, while inorganic filters include titanium dioxide and zinc oxide. Organic filters, however, have shown in some studies to have systemic effects in subjects including hormonal imbalance. In addition, negative environmental impacts of the active ingredients may potentially concern consumers.8 Inorganic sunscreen filters are considered alternatives to organic filters, and are present in sunscreens at sizes of <100nm. This size difference is cosmetically preferable to consumers, as the sunscreen is much less visible on the skin. Based on currently available data, inorganic filters are less harmful to the environment and pose minimal health risk due to low levels of absorption across the skin barrier.9 While as of yet, there is no clear consensus as to which type of sunscreen provides superior UV protection, empowering patients with information about sunscreen choices as well as education on how and when to apply sunscreen may improve patient initiative and participation in skin care and prevention. The utility of preventive methods such as sunscreen, however, is limited by other aspects of dermatologic care, such as physician constraints. A 2011 survey of primary care providers, internists and dermatologists reported that of all responding physicians, time constraints, competing comorbidities and patient embarrassment or reluctance were reported as the top three major barriers to performing full body skin examinations on patients; these factors varied by specialty. Family physicians responded with time constraints as the primary hindrance, while dermatologists re-
