Q&A: How to maximize UV exposure benefits in inflammatory diseases while minimizing risk
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While ultraviolet exposure from the sun is known to cause skin cancer, sunspots and other damage, for some with inflammatory skin conditions, this exposure can lead to beneficial outcomes.
Healio spoke to Loren Clarke, MD, chief medical officer at DermTech, about how patients with psoriasis, eczema and other inflammatory conditions can best balance their exposure to ultraviolet (UV) radiation in order to maximize benefit and avoid risk.
Healio: How does sun exposure negatively affect inflammatory skin conditions and what conditions are most affected?
Clarke: Depending on a person’s underlying skin type, exposure to sunlight causes inflammation after limited exposure. This results in compounding inflammation for those with underlying inflammatory skin conditions. Appropriately limited sun exposure should not cause additional inflammation.
UV exposure is the primary modifiable risk factor for skin cancer, including melanoma. Any disease or treatment that weakens the immune system for extended periods of time will increase the amount of damage done by UV exposure and lead to increased skin cancer rates — this can be severe and even fatal in extreme cases.
Some medications can increase the skin’s sensitivity to light and cause “photodermatitis,” or skin inflammation triggered by UV exposure.
Some inherited/autoimmune diseases (xeroderma pigmentosum, vitiligo, lupus) either increase our susceptibility to UV-induced damage or reduce our ability to repair UV-induced damage.
Healio: What skin conditions can benefit from sun exposure and why is that?
Clarke: UV exposure physiologically changes the skin. It reduces the activity of certain cells that help mount an inflammatory or immune response. For example, eczema and acne are improved by UV exposure and psoriasis and cutaneous T-cell lymphoma, a rare type of skin lymphoma, can be treated with UV exposure. In these situations, UV exposure is prescribed and dosed by health care providers in a way to minimize the added risk.
UV exposure is related to vitamin D levels — vitamin D is an important nutrient in many of our body’s functions. However, vitamin D is available as an oral supplement and as such increased sun exposure should not be the first line treatment for low vitamin D levels.
Healio: How can someone who benefits from sun exposure also protect themselves from negative effects that could cause skin cancer?
Clarke: Sun-safe behaviors include using appropriate sun block or sunscreen, wearing protective clothing and avoiding peak hours of sun exposure, which are from 11 a.m. to 2 p.m. Using sun block or sunscreen does not block the benefits of sunlight. Incidental sun exposure and appropriate time-limited exposure during nonpeak hours can confer benefits while minimizing increased risk. It is recommended that you consult with your health care provider to assess risks and needs. Vitamin D supplements can be a safe and helpful method to offset low vitamin D levels. It is also important to note that sunlight or UV light is a primary modifiable driver of skin aging. Wrinkling, sunspots and freckling are caused, in part, by sun and UV exposure.
Healio: How should someone judge if they should be getting more or less sun exposure?
Clarke: Each person is unique and has unique risk factors. The best way to judge this is to consult a health care provider. Measuring vitamin D levels in the blood is a reasonable method of evaluation. Some signs of excess sun exposure include sunburn, increasing tan, freckling and/or sunspots.
Healio: Why is this information important for individuals with inflammatory skin diseases?
Clarke: It is helpful to reiterate that UV light is the component of sunlight that induces DNA damage and ultimately skin cancer risk. While UV light can help with some skin conditions, exposure to UV light increases skin cancer risk and skin aging. The same UV light can be filtered or divided so that only the intended part of the light is getting to the skin. When directed by a health care provider, the risk can be minimized using these filtered light sources. In some cases, a health care provider may recommend some exposure to natural sunlight. Just as doses are imperative with medications, doses of sunlight (recommended and limited time of exposure) should be adhered to.
Healio: What research is underway in this area and what research is needed for the future?
Clarke: A simple way to think about skin cancer-related research is to divide it into two groups — preventive research and treatment research. In the preventive research arm, effort is being made to identify substances that can be ingested to reduce UV damage — “oral sunscreen,” in a way. One of the largest breakthroughs in the last few years is the discovery that oral nicotinamide, a less common variant of vitamin B3, can be protective against non-melanoma skin cancer. Research has also been conducted on the benefits of acetaminophen, aspirin and ibuprofen with varying results.
Healio: When should sun exposure be discussed with a dermatologist?
Clarke: It is a good idea to discuss skin cancer risk and sun exposure with your dermatologist at each visit. While there is not a consensus recommendation for skin cancer screening, a regular evaluation by a dermatologist is prudent — especially for those with increased risk including those with inflammatory skin conditions.
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