Development and external validation study of a melanoma risk prediction model incorporating clinically-assessed naevi and solar lentigines.

Background Melanoma risk prediction models could be useful for matching preventive interventions to patients' risk. Objectives To develop and validate a model for incident first-primary cutaneous melanoma using clinically assessed risk factors. Methods We used unconditional logistic regression with backward selection from the Australian Melanoma Family Study (461 cases and 329 controls) in which age, sex and city of recruitment were kept in each step, and we externally validated it using the Leeds Melanoma Case-Control Study (960 cases and 513 controls). Candidate predictors included clinically assessed whole-body naevi and solar lentigines, and self-assessed pigmentation phenotype, sun exposure, family history and history of keratinocyte cancer. We evaluated the predictive strength and discrimination of the model risk factors using odds per age- and sex-adjusted SD (OPERA) and the area under curve (AUC), and calibration using the Hosmer-Lemeshow test. Results The final model included the number of naevi >= 2 mm in diameter on the whole body, solar lentigines on the upper back (a six-level scale), hair colour at age 18 years and personal history of keratinocyte cancer. Naevi was the strongest risk factor; the OPERA was 3 center dot 51 [95% confidence interval (CI) 2 center dot 71-4 center dot 54] in the Australian study and 2 center dot 56 (95% CI 2 center dot 23-2 center dot 95) in the Leeds study. The AUC was 0 center dot 79 (95% CI 0 center dot 76-0 center dot 83) in the Australian study and 0 center dot 73 (95% CI 0 center dot 70-0 center dot 75) in the Leeds study. The Hosmer-Lemeshow test P-value was 0 center dot 30 in the Australian study and This model had good discrimination and could be used by clinicians to stratify patients by melanoma risk for the targeting of preventive interventions. What's already known about this topic? Melanoma risk prediction models may be useful in prevention by tailoring interventions to personalized risk levels. For reasons of feasibility, time and cost many melanoma prediction models use self-assessed risk factors. However, individuals tend to underestimate their naevus numbers. What does this study add? We present a melanoma risk prediction model, which includes clinically-assessed whole-body naevi and solar lentigines, and self-assessed risk factors including pigmentation phenotype and history of keratinocyte cancer. This model performs well on discrimination, the model's ability to distinguish between individuals with and without melanoma, and may assist clinicians to stratify patients by melanoma risk for targeted preventive interventions.