Patterns of sunlight exposure and risk of basal cell carcinoma: A case-control study

Abstract

Background: Basal cell carcinoma is the most common keratinocyte skin cancer worldwide in fair skin colored people and its incidence is rising annually. The main risk factor for developing the disease is natural or artificial ultraviolet radiation. Different studies suggest that for development of basal cell carcinoma more important is intermittent and intense sunburns, rather than cumulative and long-term exposure to UV. However, many studies investigated the association between chronic occupational solar exposure and basal cell carcinoma.

Aim: The aim of our study was to analyze the recent clinical trends and risk factors associated with basal cell carcinoma and reveal the possible correlation between sunburn occurrences, outdoor activities, and the risk of disease development.

Design & Methods: A hospital-based case-control study was conducted, involving 47 histologically confirmed basal cell carcinoma patients. The control group, comprising 94 participants who visited the clinic for other non-cancerous skin dermatosis, was matched for age and gender with the cases.  Data on various factors like gender, age, residence, Fitzpatrick skin type, experiencing sunburn, using sunscreens, outdoor activities, use of solariums and UV therapy, were collected using an adapted questionnaire and subjected to analysis. The gathered data underwent statistical analysis.

Results: The majority of cases (n=52; 71.2%) were situated in areas exposed to sunlight (p<0.001), with a female-to-male ratio of 1.35 to 1. The nodular subtype of basal cell carcinoma emerged as the predominant form (n=49; 67.2%). Furthermore, the proportion of patients in the study cohort with Fitzpatrick phototypes I and II (n=38; 80.9%) was notably higher compared to controls (n=50; 53.2%, p=0.002). The percentage of patients with having a job related to outdoor activities in the study group (n=29; 61.7%) was significantly higher than in controls (n=36; 38.3%) - OR=3.27 (95%CI - 1.58-6.78, p=0.001). The association between intermittent sun exposure and BCC development risk was not statistically significant in both study groups (OR 0.74, 95% CI 0.37-1.50, p=0.404).

Conclusions: The etiology of BCC often involves a complex interplay of various etiological factors, posing challenges in isolating each factor's specific contribution. Our study highlighted a strong association between Fitzpatrick skin types I and II and occupational exposure to sunlight, significantly increasing the likelihood of BCC development in cases compared to controls. However, we did not observe a statistically significant correlation between intermittent sun exposure and the risk of developing BCC.