Sunscreen
UV radiation exists in three forms, UVA, UVB, and UVC, in decreasing order of wavelength. While all of the UVC and most of the UVB rays are absorbed by the ozone layer, UVA rays reach and penetrate the skin, causing increased melanin production, premature skin aging, and melanoma development through gene damage and mutation (Bais et al., 2015; Del Bino et al., 2006; Miyamura et al., 2010; Young, 2009). Melanin produced through UV radiation does not result in the aforementioned photoprotection by large melanocytes (Coelho et al., 2015). Even low exposure to such radiation causes considerable DNA damage, regardless of skin color, contradicting the common belief that dark skinned individuals are immune to UV radiation-induced melanoma (Tadokoro et al., 2003). Around 80–90% of skin cancers are associated with UV radiation exposure, showing the importance in considering non-genetic risk factors of melanoma (Parkin et al., 2011).
The primary method of UV radiation protection is sunscreen. Sunscreens contain organic or inorganic compounds that filter against UVA and UVB rays. Organic filters contain compounds like oxybenzone, avobenzone, octocrylene, and ecamsule that absorb high-intensity UV rays, while inorganic filters contain compounds like titanium dioxide and zinc oxide that deflect UV rays away from the skin (Geoffrey et al., 2019).
Numerous studies support the effectiveness of sunscreen for melanoma (All About, 2022; Ghiasvand et al., 2016; Green et al., 2011). For instance, a study conducted by Green AC, Williams GM, Logal V, et. al. found that daily sunscreen use during their 4.5-year study significantly reduced the risk of melanoma nearly 15 years after completion (Green et al., 2011). Such effectiveness can be increased when the sunscreen’s sun protection factor (SPF), which is determined by laboratory tests on a patch of skin, is higher (Ghiasvand et al., 2016). Experts recommend all skin types to apply sunscreen with a SPF of at least 30 both prior to and during sun exposure (Gordon et al., 2009; Sunscreen, n.d.).
Racial Differences in Melanoma Skin Cancer
Skin colors are determined by the amount of melanin produced by melanocytes. Individuals with darker skin have larger melanosomes that better protect the epidermal cells of the skin by absorbing and deflecting UV radiation (Kaidbey et al., 1979). Consequently, genetic characteristics that may increase the risk of melanoma – light skin tone and eye color, freckles, blonde hair, and moles – majorly pertain to white populations (Gandini et al., 2005). In a study conducted by the Surveillance, Epidemiology, and End Results Program (SEER), the highest incidence of melanoma between 2015 and 2019 occurred in whites: 64.1/100,000 persons (Cancer Stat, 2019).
However, although the incidence of melanoma in black populations in the same SEER study was considerably less (1.9/100,000 persons), studies show that survival rates in these populations (71% 5-year survival) are lower when compared to whites (93% 5-year survival) due to difficulties in identification, socioeconomic factors, and misconceptions (Cancer Stat, 2019; Culp & Lunsford, 2019; Pollack et al., 2011).
The overall darker skin pigmentation of black populations makes symptoms of melanoma, such as developments and changes in moles, difficult to find (Culp & Lunsford, 2019). Moreover, melanoma symptoms for black populations manifest in obscure places like the inner mouth surface, toe nails, and soles (Madankumar et al., 2016). Thus, early melanoma in black populations is often unnoticed or misdiagnosed, delaying diagnosis and significantly decreasing the survival rates (Culp & Lunsford, 2019; Tucker & Goldstein, 2003).
Socioeconomic factors also contribute to the poor prognosis and survival of black populations. When comparing white and black populations, the difference in educational attainment is statistically significant with 35 percent of white adults and 21 percent of black adults earning at least a bachelor’s degree (American Community Survey, 2019). Moreover, non-hispanic white populations have a significantly greater socioeconomic status (SES) than blacks, as can be seen by the percent of children in poverty for each racial group in 2019: 10 percent whites, 31 percent blacks (Children in Poverty, 2019). Individuals with low education and SES were found to lack knowledge about melanoma, hindering proper prevention, early detection, and effective patient-physician communication (Pollitt et al., 2011). Furthermore, low SES prevents individuals from accessing health care facilities through insurance and transportation, leading to late diagnosis and treatment and thus, poorer clinical results (Harvey et al., 2014; Jiang et al., 2015; Watson et al., 2016).
A majority of the black population incorrectly believe that they have immunity against skin cancer because of their pigmented skin, although many studies indicate that they are still at risk (Lozano et al., 2012). Studies revealed that this misconception even exists among health professionals, as many doctors do not educate black individuals on melanoma prevention and risk (Kim et al., 2009). This misconception may be continuing due to the limited melanoma research on black populations and the white-dominated focus of public sun protection interventions (Buster et al., 2012; Calderón et al., 2019). This misperception causes diagnosis and treatment delays among black individuals, advancing melanoma stages to potentially fatal levels (Hansen, 2014; Jacobsen et al., 2016).
Furthermore, black populations were found to not apply sunscreen routinely (Andreeva et al., 2009; Coups et al., 2013; Weiss et al., 2012). In a study conducted on the sun protection behaviors of different racial and ethnical populations in the U.S., regular sunscreen use was highest in whites (37.6%) and lowest in blacks (13.1%) (Calderón et al., 2019). Possible causes for such differences may be the aforementioned misconception of immunity among black individuals, as well as the general lack of knowledge on melanoma in minority groups compared to whites due to lower education levels and neglect in public sun protection interventions (Calderón et al., 2019; Ma et al., 2007).