**1. Introduction**

Sunscreen offers an integrative health approach to sun protection, to prevent skin cancers. Skin cancer is among the most common forms of cancers in the United States (U.S.), affecting nearly 10,000 people every day [1]. Over three million cases of non-melanoma skin cancers (NMSC), including basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), are diagnosed annually, with one in five Americans projected to develop the cancer during their lifetime [2]. The incidence rates may vary across states and regions, depending upon sociodemographic and environmental factors, and rates of cancer screening [1,3].

**Citation:** Sharma, M.; Asare, M.; Largo-Wight, E.; Merten, J.; Binder, M.; Lakhan, R.; Batra, K. Testing Multi-Theory Model (MTM) in Explaining Sunscreen Use among Florida Residents: An Integrative Approach for Sun Protection. *Healthcare* **2021**, *9*, 1343. https:// doi.org/10.3390/healthcare9101343

Academic Editor: Wolfgang Uter

Received: 13 August 2021 Accepted: 7 October 2021 Published: 10 October 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Florida has the second highest incidence rate of skin cancers in the U.S., which can be partly explained by its high ultraviolet (UV) index [3–5]. Over 600 Floridians die of skin cancer each year, and this mortality rate has doubled over the past few decades [3]. These rates are also underestimated, due to lack of NMSC reporting in cancer registries [1,6]. However, a report of the Medical Expenditure Panel Survey indicated that nearly 4.3 million people were treated for NMSC in 2015 in the U.S. [6]. Collective evidence suggests an increase in the national, as well as global, incidence of NMSC compared to other forms of non-preventable cancers combined [1,7–10].

Given the continued increase in incidence, the healthcare cost associated with skin cancer is substantial, making it the fifth most expensive disease in the U.S. [1,11]. Nearly five million people have been treated for some form of skin cancer, which cost the nation over eight billion dollars [4]. This underscores the need for adopting and reinforcing costeffective yet simple preventive strategies, especially sunscreen use, which is the single most modifiable risk factor of skin cancer, other than avoiding ultraviolet (UV) exposure [2,12].

Other risk factors for skin cancers include old age, race, family history, male gender, long-term skin inflammation, and immunocompromised status [7,13,14]. NMSC occurs more often in white people than people of color, due to lower melanin (photo-protective pigment) production in the former group [14]. However, the worst prognosis was noted among people of color [15,16]. According to the previous reports, incidence and mortality associated with NMSC among people of color may be underestimated, given the scarcity of data [14]. UV radiation from the sun or indoor tanning machines has been directly associated with the development of skin cancer [12]. The risk of skin cancer can be significantly reduced by limiting sun exposure [12]. The American Cancer Society (ACS) recommends avoiding the sun during peak hours (10 am–4 pm), seeking shade when outdoors, wearing sun protective clothing, including sunglasses and a wide-brimmed hat, and frequently applying sunscreen (SPF > 30) with both UVA and UVB (broadband) protection [17].

Proper sunscreen use has been linked to a reduction in squamous cell and malignant melanoma skin cancer development, by 40% and 50%, respectively [18,19]. The best method of preventing skin cancer in the population is to increase sunscreen usage in the community, to protect skin from harmful UV radiation exposure. Regrettably, the utilization of sunscreen is low despite the well-established protective benefits of sunscreen in preventing skin cancers [18,19]. Personal barriers (dislike of the appearance or feel of sunscreen), time constraints, and economic barriers were commonly cited contributing factors to sunscreen underuse [20]. According to the 2015 National Health Interview Survey-Cancer Control Supplement analysis, sunscreen use in U.S adults was only 31.5% [21]. Only 10% of Americans reported using sunscreen daily with nearly half (47%) indicating that they have never used sunscreen. This highlights the importance of behavior change community-based interventions to address the underutilization of sunscreen [21].

Previous studies utilized a range of theoretical frameworks, including a transtheoretical model, health belief model, precaution adoption model, social cognitive theory, protection motivation theory, inoculation theory, and theory of planned behaviors in guiding public health interventions targeted at reducing the risk of skin cancer by promoting sunscreen usage, and thereby decreasing sun exposure [22–26]. Such theoretical interventions have received some success in identifying gaps in knowledge, attitudes, and practices, but overall, their impact has been limited in promoting sunscreen usage behaviors. Additionally, public health experts and behavior change theorists have been cognizant of the limitations of public health theories, as many of these do not provide robust estimations of the likelihood of initiation and sustenance. Behavioral change is a long-term process, and if a behavior is not sustained long enough then a relapse is more likely. Therefore, it is vital to obtain a better understanding of the initiation and sustenance of sunscreen usage in the community, to reduce the increasing incidence risk of skin cancer. Sharma (2015) attempted to address these gaps by combining constructs of popular theories and models in a way that predicted the initiation and sustenance of a behavior [27]. Therefore, this

study aims to investigate the predictability of adopting and continuing sunscreen usage behavior among a high UV index risk population: Florida residents.
