Possible Explanations for Rising Melanoma Rates Despite Increased Sunscreen Use over the Past Several Decades

Abstract

The incidence of cutaneous melanoma continues to rise despite the increased use of sunscreens within the last several decades. Some research even suggests that the use of sunscreen is associated with increased rates of melanoma. Given the aggressive, and often deadly, nature of cutaneous melanoma, the aim of this communication is to better elucidate the relationship between sunscreen use and melanoma development and if there are other preventative measures to be aware of. A search was performed to identify the studies that have investigated melanoma development in individuals who used sunscreen and those who did not. Study limitations and possible confounding variables were identified, which guided a subsequent search to determine what data were available to support that these limitations and confounding variables may explain the perplexing association between sunscreen use and melanoma development. Five hypotheses were generated, which were related to increased awareness and reporting, the relationship between sunscreen use and the duration of sun exposure, the importance of broad-spectrum protection, and the effect of sunscreen on reactive oxygen species formation. The main conclusion is that more recent studies that control for confounding variables are required to determine the true effect of adequate broad-spectrum sunscreen use today on the development of melanoma.

Keywords: cutaneous melanoma; reactive oxygen species; sun exposure; sun protection; sunscreen.

Figure 1

Age-standardized incidence rates (ASRs) per 100,000 for Germany [9], USA [10], UK [11], Australia [12], Italy [12]. Note: No data on ASR available for Italy from International Agency for Research on Cancer (Cancer Over Time dataset) after 2012. For the UK, data points in the source represent intervals (e.g., 2002–2004) rather than individual years as in the USA and Germany. The last date of this interval for each year’s x-axis tick was chosen for comparable visualization.

Figure 2

Age-standardized mortality rate per 100,000 (world normal population). Melanoma of skin: Australia—Germany—Italy—United Kingdom—USA [11]. Lines were smoothed using the LOESS regression algorithm (bandwidth: 0.25).

Figure 3

Age-standardized incidence rate per 100,000 in 2022 in EU-27. Melanoma of skin; both sexes, all ages [14].

Figure 4

Age-standardized incidence rate per 100,000 in 2022. Relative changes (in %) of each country compared to EU-27. Melanoma of skin; both sexes, all ages [14].

Figure 5

Age-standardized incidence rate per 100,000 projection 2040 compared to 2022. Relative changes (in %) of each country. Melanoma of skin; both sexes, all ages [14].

Figure 6

Rise in sunscreen usage in the USA from 2004 to 2020. Note: Percentage of adults aged 18 years and older (USA) who always or most of the time protect themselves from the sun by using sunscreen with a sun protection factor of 15 or higher [22].

Figure 7

Comparative analysis of Google search interest related to sun-protection usage from January 2004 to December 2018 in the USA, the UK, and Germany. Data were sourced from Google Trends using the search terms ‘sunscreen’ for the USA and UK and ‘sonnencreme’ for Germany. Solid lines indicate actual search interest over time, while dashed lines depict trendlines for each respective region. The values represent search interest relative to the highest point on the chart for the given region and time period. A value of 100 denotes peak popularity for the term; 50 indicates that the term is half as popular, and 0 means insufficient data for the term. It is evident that search terms were used more frequently during summer months and have been increasingly searched over time, indicating a growing interest in sun-protection usage [23].

Figure 8

Non-business-purpose trips of EU residents (EU-27) to other foreign countries in summer (June, July, August) and winter (December, January, February) months. Minimum duration of vacation 4 nights and over [46].