The risk of melanoma in patients with chronic lymphocytic leukemia; a population-based study

Introduction: Melanoma is a highly malignant tumor that has been repeatedly reported in chronic lymphocytic leukemia (CLL) patients. We aim to assess the epidemiologic characteristics of this association and emphasize the importance of carefully approaching such cases. Methods: Patients who were diagnosed with CLL between 2000 and 2015 and registered in the Surveillance, Epidemiology and End Results (SEER) database of the US National Cancer Institute were identified using the SEER*stat software (version 8.3.5). The Multiple Primary Standardized Incidence Ratios session of the SEER*stat software (version 8.3.5) was used to calculate the observed/expected (O/E) ratios of melanoma. Results: 48,876 CLL cases were reviewed, of which 474 developed a second primary melanoma of the skin. O/E ratio was 2.07 (95% CI 1.89-2.27), and excess risk was 9.7 per 10,000. The increase in melanoma risk was higher within the first 5 years following CLL diagnosis; O/E = 2.22 (95% CI 1.56-2.14) and excess risk was 10.43 per 10,000. It was higher in males compared to females O/E was 2.10 (95% CI 1.89-2.33) and 1.98 (95% CI 1.62-2.40) in males and females, respectively, and in people aged 45-64; O/E = 2.30 (95% CI 1.95-2.70). Out of 7827 CLL patients receiving chemotherapy, 70 later developed melanoma with a significant O/E of 2.28 (95% CI 1.77-2.88) and an excess risk of 10.66 per 10,000. Conclusion: CLL increases the risk of developing melanoma, especially within 5 years of the diagnosis, and in white males aged between 45-64 years. It is crucial to keep rigorous screening, high-suspicion and close follow-up for recurrence in consideration while managing these patients.