Self screening for risk of melanoma: validity of self mole counting by patients in a single general practice

To validate self screening by patients of high mole counts, assess the within family association of sun protection behaviour and mole counts, and estimate prevalence of risk factors for melanoma.

Systematic sample of families from a single affluent general practice population in Wessex.

Subjects completed a questionnaire about risk factors for melanoma and counted their moles. Subsequently a mole count was done by a general practitioner trained at dermatology clinics.

Validation of self counts by observer's count. Within family association of sun protection behaviour and mole counts; self reported risk factors.

199/237 subjects (84%) returned the questionnaire; 212/237 (89%) were examined. High counts by patients on the front of the trunk (> 7 moles of > or = 2 mm) were reasonably sensitive (79%), predictive (75%), and specific (97%) of the observer's mole counts (kappa = 0.74), unlike arm or total body counts. Sun protection behaviour correlated between individuals and other family members (Spearman's coefficient r = 0.50, P < 0.01). In the past three months 15/114 adults (13.2%, 95% confidence interval 7.0% to 19.4%) reported any change in a mole and 6/114 (5.3%, 2.0% to 11.1%) "major" changes; 6/109 adults (5.5%, 2.1% to 11.6%) had both high mole counts and freckling.

Asking patients to count trunk moles could be a feasible way of identifying patients at high risk of melanoma. Concentrating on reported major changes in moles should avoid considerable workload in general practice. The generalisability of these findings and the adverse effects, net benefit in earlier diagnosis and prevention, and workload implications of such self screening need further research.