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.60 General protection guidelines published by the American Cancer Society include avoiding sun exposure when UV rays are strongest (between 10 AM and 4 PM); wearing protective clothing; wearing a hat that shades the neck, face and ears; wearing sunglasses that block UV rays; and properly using a broad spectrum sunscreen with a sun protection factor (SPF) of 30 or higher.61

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.62 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.62,63 It is of note that UV-B radiation is 1,000 - 10,000 times more carcinogenic than UV-A radiation.64,65

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.66 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.64,67,68 Table 3 lists selected FDA-accepted sunscreen formulations, the concentration of active ingredients, and their UVR spectrum.

Table 3. Some FDA Accepted Sunscreen Agents.67,68
Ingredient Maximum
FDA
approved %
Concentration
Maximum
(nm)
Absorption
UV
Coverage
Spectrum
Inorganic UV filters
Zinc Oxide 25 Variable * UV-B, UV-A
Titanium dioxide 25 Variable * UV-B, UV-A
Organic UV filters
Aminobenzoates
 para-Aminobenzoic acid
 Padimate O (octyl dimethyl PABA)

15
8

283
311

UV-B
UV-B
Cinnamates
 Cinoxate (2-ethoxyethyl p-methoxycinnamate)
 Octinoxate (octyl methoxycinnamate)

3
7.5

289
311

UV-B
UV-B
Salicylates
 Trolamine salicylate **
 (triethanolamine salicylate)
 Homosalate (homomenthyl salicylate)
Octisalate (octyl salicylate)

12

15
5

260-355

306
307

UV-B

UV-B
UV-B
Others
 Octocrylene (2-ethylhexyl 2-cyano-3,
   3- diphenylacrylate)
 Ensulizole (phenylbenzimidazole
   sulfonic acid)

10

4

303

310

UV-B, UV-A

UV-B
Benzophenones
 Oxybenzone (benzophenone-3)
 Dioxybenzone (benzophenone-8)
 Sulisobenzone (benzophenone-4)

6
3
10

288, 325
352
366

UV-B,UV-A
UV-B,UV-A
UV-B,UV-A
Dibenzoylmethanes
 Avobenzone (butyl methoxydibenzoylmethane,
   Parsol 1789)

3

360

UV-B, UV-A
Anthralates
 Meradimate (menthyl anthranilate)

5

340

UV-A
Camphors
 Ecamsule (terephthalylidene dicamphor
   sulfonic acid, Mexoryl SX)

3

345

UV-B, UV-A
* Spectral absorption depends of particle size.
** Exhibits both inorganic and organic blocking properties.

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.66,68,69 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.69

Table 4. Some Commercially Available Lip Balms.
Product Manufacturer SPF
Lip Repair + Protect Aquaphor 30
Anew Solar Advance Lip Sunscreen Avon 30
Aloe Vera with Vitamin E Lip Balm Banana Boat 45
Sport Performance Sunscreen Lip Balm Banana Boat 50
Healing Lip Balm CeraVe 30
Lip Shine Colorescience 35
CVS Health Lip Balm Broad Spectrum CVS Health 30
UV Lip Balm Broad Spectrum EltaMD 31
Hawaiian Tropic Lip Balm Hawaiian Tropic 45
LipDrink Lip Balm Jane Iredale 15
Sun Care Lip Protector Sunscreen Broad Spectrum Mary Kay 15
Super BB All-in-One Cheek and Lip Balm Physicians Formula 20
Essentials Lip Shield Rodan + Fields 25
Cle de Peau Beaute UV Protective Lip Treatment Shiseido Cosmetics 30
Sunscreen Lip Balm (6 Flavors) Sun Bum 30
Sports Sunscreen Lip Balm Broad Spectrum Target Up & Up 50

Regardless of the product chosen, sunscreens should be applied liberally 15-30 minutes prior to exposure to UVR.61,66 They should be reapplied liberally after any vigorous activity that may wash or rub away the product.61,69 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.