Skin Cancer and Prevention Flashcards
Types of skin cancer
- basal cell carcinoma (BCC)- squamous cell carcinoma (SCC)- melanoma: less prevalent but is major cause of death from skin cancerBCC and SCC are non-melanoma skin cancers. they are rarely lethal but surgical tx is painful and often disfiguring
Risk factors of skin cancer
- UV light exposure - Fair complexion, areas closer to the equator receive higher amounts of UV exposure: Intermittent, intense sun exposure is much more closely correlated with melanoma than chronic, occupational exposure- Age – people of over 75 years have a 50 – 300 x higher risk than those under 45 years- Large number of atypical nevi (moles): Strongest risk factor for malignant melanoma in fair-skinned populations- Family history of skin cancer- Actinic keratoses (premalignant condition)- Ionizing radiation – 3-5 fold increase with therapeutic radiation- Chronic immunosuppression – HIV, patients on long term immunosuppressants- Viruses - Human papilloma virus infection types 16 and 18 increase risk of anogenital SCC- Chronic arsenic exposure- Chronic skin inflammation
What is Minimum Erythema Dose (MED)?
- MED - smallest amount of sunlight exposure necessary to induce a slight redness of the skin within 24h after exposure- American Academy of Dermatology recognises 6 skin types, according to the amount of melanin normally present in the skin- MED is affected by latitude, altitude, reflection off sand/water/concrete, time of day
Sun protection tips to reduce skin cancer
- Avoid sun exposure between 10am and 2pm- Cover up with broad-rimmed hats, sunglasses, visors, clothing and umbrellas when out in thesun- Opt for protective swimwear and umbrellas with Ultraviolet Protection Factor (UPF) 50, which is a rating system to measure how much of the sun’s ultraviolet rays are absorbed or blocked by the fabric- Apply a broad-spectrum sunscreen of at least Sun Protection Factor (SPF) 15 to exposed areas of the skin including the ears (SPF 30-50 if fair skinned)- Use a water-resistant sunscreen when doing intensive sports where you perspire a lot or when swimming- Reapply every two hours
What are sunscreens, how shld they be applied and stored?
- Most sunscreen products work by absorbing, reflecting, or scattering sunlight- Apply 15 minutes before going outdoors. This allows the sunscreen (of SPF 15 or higher) to have enough time to provide the maximum benefit.- Use enough to cover the entire face and body (avoiding the eyes and mouth). An average-sized adult or child needs at least one ounce of sunscreen (about the amount it takes to fill a shot glass) to evenly cover the body from head to toe- Reapply at least every 2hours, and more often if swimming or sweating- Protected from excessive heat and direct sunlight
How to choose a sunscreen - SPF?
SPF = sun protection factor- Ratio of the minimal dose of solar radiation that produces perceptible erythema (minimal erythema dose) on sunscreen-protected skin compared with unprotected skin- E.g A patient with Type 1 skin (MED of 20 mins) could theoretically stay out in the sun for 5 hours without any evidence of burn after applying a product with an SPF of 15 -> 15 times longer (15x20)- SPF is not directly related to time of solar exposure but to amount of solar exposure
How to choose a sunscreen with broad spectrum?
- Broad spectrum = sunscreen contains ingredients that effectively protect against UVA rays as well as UVB- Solar ultraviolet radiation is approximately 200–400 nm in wavelength- The medium wavelengths (290–320 nm, known as UVB) cause sunburn- The long wavelengths (320–400 nm, known as UVA) are responsible for many photosensitivity reactions and photodermatoses- Both UVA and UVB contribute to long-term photodamage and to the changes responsible for skin cancer and ageing
How to choose a sunscreen - Active ingredient
Inorganic filters/physical sunscreens: Zinc oxide and titanium dioxideOrgan filters/chemical sunscreens: aminobenzoic acic (PABA) and trolamine salicylate -> not generally safe and effective. insuff data: octocrylene, oxybenzone, avobenzone etc- Organic filters include a variety of aromatic compounds that absorb UV radiation and convert it to a negligible amount of heat- Some organic agents such as cinnamates and salicylates specifically absorb UVB- Combining filters with varying UV absorption spectra to produce broad- spectrum sunscreens- Inorganic filters are mineral compounds such as zinc oxide and titanium dioxide that are believed to reflect and scatter UV light over a wide range of wavelengths.- Inorganic sunscreens offer broad-spectrum protection against UVA and UVB
How to choose a suncreen - dosage form
- Sunscreen sprays, oils, lotions, creams, gels, butters, pastes, ointments, and sticks are proposed as safe and effective- FDA proposes that it needs more data for sunscreen powders- As sunscreen ingredients are oil-soluble, the most widely commercialized sunscreen products (eg, lotions and creams) are oil-in-water emulsions, in which microscopic drops of oily materials are dispersed in a continuous water phase that typically contains also other polar ingredients like glycerin or glycols- Lotions are thinner and less greasy than creams and are generally preferred for application over large body areas
How to choose a sunscreen - water resistance
- Sunscreens cannot claim to be waterproof but can be labeled water resistant for either 40 or 80 minutes
How to choose a sunscreen - irritant and allergies
- Adverse reactions from sunscreen ingredients have been reported and include allergic and irritant contact dermatitis, phototoxic and photoallergic reactions, contact urticaria, and rare anaphylactic reactions- Most of the UV filters known to be contact sensitizers such as para-aminobenzoic acid (PABA), amyl-dimethyl-PABA, or benzophenone-10 are now rarely used in sunscreen manufacture- The top three allergens in sunscreens are benzophenone-3, DL-alpha-tocopherol, and fragrances- Inorganic sunscreens are stable, and in contrast to organic filters, have a low irritating and sensitizing potential and are suitable for people with sensitive ski
How to choose a susncreen - cosmetic properties
- Sunscreen-containing cosmetics (eg, facial moisturizers, foundations) may improve the photoprotection compliance- Most cosmetic products are formulated to provide a SPF of 15 to 30 and may or may not be labeled as broad spectrum- Cosmetics providing broad-spectrum protection should be preferred to those containing only UVB filters
Sunscreen counselling points
- Apply sunscreen to dry skin at least 15 to 30 minutes before sun exposure- Apply generously, including frequently forgotten spots: The “teaspoon” rule -> ears, nose, hands, lips, back of neck, top of feet, along hairline, areas of head exposed by balding- Reapply every 2 hours at a minimum, even on cloudy days- Reapply after heavy sweating, swimming, and toweling off- When using sunscreen sprays, spray and then rub the product into the skin to ensure uniform coverage- Apply sunscreen before insect repellent when using both (moisturiser -> sunscreen -> insect repellent)- Do not use sunscreen on children younger than 6 months of age- Expiration date - Sunscreen without an expiration date has a shelf life of no more than three years, but its shelf life is shorter if it has been exposed to high temperatures
Medications that may cause photosensitivity
- Photosensitivity = heightened skin sensitivity or an unusual reaction when exposed to UV radiation- ABs: tetracyclines, FQs, sulfamethoxazole, trimetoprim- NSAID: ibuprofen, naproxen, celecoxib- Retinoids: acitretin, isotretinoin- Oral contraceptives and estrogen- Antifungals: flucytosine, griseofulvin, voriconazole- psoralens: methoxsalen, trioxsalen- phenothiazines- sulphonyureas- amiodarone
Early detection: what to look out for
- Using sun protection consistently from an early age is the strongest defense against developing skin cancer- The American Academy of Dermatology recommends that all adults do monthly skin self-exams: High risk patients- see a dermatologist annually, or more frequently if they see something suspicious or have risk factorsLook for: - Changes in colour, size, or surface texture of moles or birthmarks- New skin growths, especially if they crust, bleed, itch or hurt- Sores or wounds which do not heal within a month
