Absolute Risk of Second Primary Cancer After Initial Melanoma Diagnosis

Overview

In a large population-based cohort of 154,695 individuals diagnosed with a first primary melanoma in New South Wales, Australia, 23.7% developed a second primary cancer during a median follow-up of 7 years. The most common second primary cancer was another melanoma (12.7%), with a 5-year absolute risk of 7.6%, followed by prostate, breast, and colon cancers with lower absolute risks.

Background

Cutaneous melanoma incidence is rising in fair-skinned populations, and while prognosis after a first melanoma is generally favorable, patients have an elevated risk of developing subsequent primary melanomas and other cancers. Previous studies often used cause-specific models ignoring competing risks, limiting clinical applicability. This study aimed to estimate absolute risks of second primary melanomas and other cancers accounting for competing risks, to better inform patient surveillance and education.

Data Highlights

Key Findings

• 23.7% of individuals with a first primary melanoma developed a second primary cancer during follow-up.
• 12.7% developed a second primary melanoma (invasive or in situ), with a 5-year absolute risk of 7.6%.
• Prostate cancer was the most common non-melanoma second primary cancer in males, with a 5-year risk of 2.8%.
• Breast cancer was a common second primary cancer in females, with a 5-year risk of 0.7% (2.8% female-specific incidence).
• Colon cancer had a 5-year absolute risk of 0.6% following initial melanoma diagnosis.
• Accounting for competing risks of death and other cancers provides more clinically relevant absolute risk estimates for patient counseling.

Clinical Implications

Patients diagnosed with a primary melanoma require long-term skin surveillance due to the substantial risk of developing a second primary melanoma. Awareness of elevated risks for other cancers such as prostate, breast, and colon cancer can guide tailored screening and patient education. Using absolute risk estimates that consider competing risks can improve clinical decision-making and patient communication.

Conclusion

This large population-based study demonstrates that individuals with a first primary melanoma have a significant absolute risk of developing a second primary melanoma and other cancers, underscoring the need for ongoing surveillance and comprehensive patient counseling.

References

1. Cancer Institute NSW / NSW Cancer Registry / 1982-2019 -- Evaluating the Absolute Risk of a Second Primary Cancer Following Initial Melanoma Diagnosis