Elevated risk of second primary cancer in patients with cutaneous malignant melanoma: A nationwide cohort study in Taiwan

Background: It has been described that Caucasian patients with cutaneous malignant melanoma (CMM) are at an increased risk of developing second primary cancer. However, no large-scale study of second primary cancer in CMM patients has been conducted among Asians, who have distinctly different skin types. Objective: We sought to access the risk of second primary cancer among CMM patients based on data from a nationwide database in Taiwan. Methods: Utilizing the catastrophic illness database of Taiwan's National Health Insurance Research Database, we identified 2665 CMM patients without prior cancers in the period from 1997 to 2008. The standard incidence ratio (SIR) of each cancer was calculated. Results: The mean age ± standard deviation at diagnosis of CMM was 62.2 ± 17.4 years. The mean annual incidence was 0.9 cases per 100,000 people. The overall cancer risk was elevated (SIR: 2.54), with younger patients having a higher risk. The risk remained elevated during the first five years after the CMM diagnosis. CMM patients had a higher risk of developing cancers of eye (SIR: 275.68), connective tissue (SIR: 43.45), brain (SIR: 21.03), and non-melanoma skin cancer (SIR: 17.71). Conclusion: CMM patients have a 2.54-fold risk of second primary cancer, with younger patients at increased risk. The risk remains elevated during the first five years after the diagnosis of CMM. The sites with highest risk of second primary cancer are eye, connective tissue, brain, and non-melanoma skin cancer.