Survival rates for melanoma are influenced by the thickness of the tumor.

According to extensive population studies, skin melanomas with a thin thickness, typically defined as having a thickness of 1.0 millimeter or less, account for up to 72% of all melanomas. In Australia, where the highest melanoma incidence in the world is reported, comprehensive oncology registries have been maintained for decades, providing a unique foundation for the widespread detection and regular monitoring of thin melanomas.

Understanding how subtle changes in thickness correlate with patient survival can provide insights for clinical assessments in long-term monitoring and treatment.

In the study titled “Risk of Death from Melanoma and Other Causes in Patients with Thin Cutaneous Melanoma,” published in JAMA Dermatology, researchers analyzed population registries in Australia from 1982 to 2014.

All patients were diagnosed with invasive melanomas measuring 1.0 millimeter or less. The data included age, sex, anatomical location, and detailed death records.

The researchers conducted an analysis of causes and competitive risks to determine the rates of melanoma-related and unrelated mortality in the long term. To assess changes in risk, Breslow thickness measurements were considered in increments of 0.1 millimeters.

Of the 144,447 patients included in the study, the overall survival rate for melanoma over 20 years was 91.9%, but survival rates varied significantly among groups based on tumor thickness. Among patients with tumors thinner than 0.8 mm, 94.2% survived, while among those with tumors measuring 0.8-1.0 mm, 87.8% survived.

The findings support the use of a Breslow thickness threshold of 0.8 mm to differentiate between high-risk and low-risk patients, endorsing its continued inclusion in the staging criteria of the American Joint Committee on Cancer. The results also underscore the need for long-term monitoring of this patient population, as melanoma mortality continues to accumulate even after 20 years.