1. Patients with four or more tattoo sessions or three or more large tattoos had lower odds of melanoma.
2. One tattoo session was linked with higher odds of melanoma, especially among women.
3. Patients who received their first tattoo before age 20 had lower odds of invasive melanoma.
4. Study included 1,167 melanoma cases and 5,835 controls in Utah, with adjustments for demographic and health factors.
5. Controls lacked data on indoor tanning, pigment phenotype, sunburn history, and family history, leading to possible unmeasured confounding.

Source: Journal of the National Cancer Institute