Prevalence of left-sided melanomas in an Irish population

A predominance of melanomas on the left side of the body has recently been described. No associations between tumour laterality and gender, age or anatomical site have been identified.

The aim of this study was to investigate the prevalence of left-sided melanomas in an Irish population and to examine potential associations with various patient and tumour characteristics.

A retrospective chart review of patients with cutaneous melanoma who were treated over a 10-year period was carried out. Lateral distribution of melanoma on either side of the body was compared using χ(2) analysis and evaluated by gender, age group, anatomic location, histologic subtype and Breslow depth.

More melanomas occurred on the left side (57%, P = 0.015), and this finding was particularly significant in females. For both genders combined, there were no statistically significant differences in laterality by age group, anatomic location, type of melanoma and Breslow depth. There were significantly more superficial spreading melanomas on the left side in both men and women.

This study demonstrates a predominance of left-sided melanomas in Irish patients. While a number of demographic and molecular associations have been proposed, further research is required to fully explain this phenomenon.