Prevention

Given the strong etiologic link between UVR and SC, reducing exposure to sunlight or other forms of UVR is the single most important measure in preventing SC.63 General protection guidelines published by the American Cancer Society include avoiding sun exposure when UV rays are strongest (between 10 AM and 4 PM); covering up exposed skin; wearing a hat that shades the neck, face and ears; wearing sunglasses; and using a sunscreen with a sun protection factor (SPF) of 30 or higher.64

The SPF of a sunscreen product is determined using a calibrated artificial UV radiation source to induce minimal erythema on skin protected by the application of 2 mg/cm2 of the test sunscreen.65 SPF is the ratio of UV radiation dose required to induce minimal erythema on protected skin versus the dose required to induce the same degree of erythema on unprotected skin.65,66 It is of note that UV-B radiation is 1,000 times more erythemogenic than UV-A radiation.67,68

Sunscreens are divided into two types: inorganic and organic. Inorganic sunscreens contain zinc or titanium dioxide and act to physically block, reflect, or scatter UV radiation.69 Organic agents have variable absorptive spectra and sunscreen manufacturers typically combine several agents to produce a broad spectrum product capable of blocking both UV-A and UV-B.67,70,71 Table 3 lists selected FDA-accepted sunscreen formulations, the concentration of active ingredients, and their UVR spectrum.

Table 3. Some FDA Accepted Sunscreen Agents.72
Agent Allowable Concentration Spectrum Blocked (nm)
Inorganic agents
Titanium dioxide 25% 290 - 350
Zinc oxide 25% 290 - 400
Organic agents
Avobenzone 3% 310 - 400
Cinoxate 3% 270 - 328
Dioxybenzone 3% 206 - 380
Ecamsule 10% 295 - 390
Homosalate 15% 290 - 315
Menthyl anthranilate 5% 200 - 380
Octocrylene 10% 287 - 323
Octyl methoxycinnamate 7.5% 280 - 310
Octyl salicylate 5% 260 - 310
Oxybenzone 6% 270 - 350
Padimate O 8% 290 - 315
Para aminobenzoic acid 15% 260 - 313
Phenylbenzimidazole sulfonic acid 4% 290 - 340
Sulisobenzone 10% 250 - 380
Trolamine salicylate 12% 269 - 320
For the prevention of SC, the product chosen should be formulated for use on the lip and provide broad-spectrum protection against both UV-B and UV-A radiation.69 Table 4 lists some commercially available broad spectrum lip sunscreens/sunblocks. As product lines and formulations are subject to change, clinicians and consumers should always check the product label. If a lip balm is not available, a broad-spectrum liquid or gel sunscreen applied to the lips may prove effective.72
Table 4. Some Commercially Available Lip Balms.
Product Manufacturer
Aloe Gator SPF 30 Medicated Lip Balm Aloe Gator Suncare Co. (Irving, TX)
Aloe Gator SPF 30 Tropical Lip Balm (various flavors) Aloe Gator Suncare Co. (Irving, TX)
Banana Boat Sport Performance Lip Balm SPF 50 Sun Pharmaceuticals, LLC
Banana Boat Aloe Vera with Vitamin E Lip Balm SPF 45 Sun Pharmaceuticals, LLC
Chaptstick Ultra 30 Pfizer Consumer Healthcare (King Mountain, NC)
Chapstick LipShield 365 Pfizer Consumer Healthcare (King Mountain, NC)
Eco Lip Sport Eco Lips, Inc. (Cedar Rapids, IA)
Five Star Lip Protection Blistex, Inc. (Oak Brook, IL)
Herpacin L Chattem, Inc. (Chattanooga, TN)
Lipcotz Lip Balm SPF 45 Fallen, Inc. (West Nirriton, PA)
RPM for Men Blistex, Inc. (Oak Brook, IL)
Sport Lip Balm SPF 30 Kiss My Face, LLC (Gardiner, NY)
SPF 30 Luxe Sport Lip Balm S&G Hampton Sun, LLC, (New York, NY)
Regardless of the product chosen, sunscreens should be applied liberally 15-30 minutes prior to exposure to UVR.69 They should be reapplied liberally after any vigorous activity that may wash or rub away the product.69,73 Finally, and perhaps more importantly, the patient should be educated that the purpose of sunscreens is to provide protection against UV radiation when one needs to be outside, but that the ultimate goal of prevention is to reduce elective sun exposure.