Abstract
IMPORTANCE: Population-based skin cancer screening is currently not recommended owing to lack of data to quantify the balance of benefits and harms. OBJECTIVE: To compare thickness-specific incidence of melanoma in screened vs unscreened patients following the initiation of a primary care-based skin cancer screening initiative. DESIGN, SETTING, AND PARTICIPANTS: This observational study of a quality improvement initiative was conducted from January 1, 2014, through December 31, 2018, among patients 35 years and older presenting for a primary care visit at primary care practices within an academic and community-based health care system during the study period. Data analysis was performed January 2020 to January 2022. INTERVENTIONS: Primary care clinicians were offered training in melanoma identification through skin examination and encouraged to offer annual screening to patients 35 years and older. MAIN OUTCOMES AND MEASURES: Thickness of melanomas diagnosed in screened and unscreened patients. RESULTS: Among 595 799 analyzed screen-eligible patients, 144 851 (24.3%) were screened at least once. Screened patients were older (median [IQR] age, 59 [49-67] vs 55 [45-66] years) and more likely to be female (82 244 [56.8%] vs 250 806 [55.6%]; P < .001) and non-Hispanic White (124 747 [86.1%] vs 375 890 [83.4%]; P < .001) than unscreened patients. After adjusting for age, sex, and race, screened patients were more likely than unscreened patients to be diagnosed with in situ (incidence, 30.4 vs 14.4; hazard ratio [HR], 2.6; 95% CI, 2.1-3.1; P < .001) or thin invasive (≤1 mm) melanoma (incidence, 24.5 vs 16.1; HR, 1.8; 95% CI, 1.5-2.2; P < .001). Screened patients were also more likely than unscreened patients to be diagnosed with in situ (incidence, 26.7 vs 12.9; HR, 2.1; 95% CI, 1.7-2.6; P < .001) or thin invasive (≤1 mm) interval melanomas (melanoma diagnosed at least 60 days after initial screening examination) (incidence, 18.5 vs 14.4; HR, 1.3; 95% CI, 1.0-1.7; P = .03). Incidence of melanoma thicker than 4 mm in unscreened and screened patients, respectively, was 3.3 and 2.7 (HR, 0.8; 95% CI, 0.4-1.4; P = .38) for all melanomas and 2.7 and 1.5 (HR, 0.6; 95% CI, 0.2-1.2; P = .15) for interval melanomas. CONCLUSIONS AND RELEVANCE: In this quality improvement study, primary care-based melanoma screening was associated with increased detection of thin melanoma, raising concern about overdiagnosis. Further studies with longer follow-up are needed to determine the influence of screening on the incidence of thick melanoma and outcomes associated with high costs and poor outcomes, such as metastasis.