The authors wrote, “Chronic lymphocytic leukemia (CLL)-phenotype monoclonal B-cell lymphocytosis (MBL) is a premalignant condition that is roughly 500-fold more common than CLL. It is unknown whether the two-fold increased risk of developing melanoma associated with CLL extends to individuals with MBL.”
The study cohort comprised 7,334 individuals from the Mayo Clinic Biobank who provided blood samples between July 2009 and April 2022. The participants were aged 40 years or older and had no previous history of hematologic malignancy. Of the 7,334 individuals, 1,151 (16%) were found to have CD-5-positive MBL, of whom 1,098 had low-count MBL (LC-MBL).
The researchers employed eight-color flow cytometry to screen for MBL. Individuals with MBL were classified as LC-MBL or high-count MBL based on clonal B-cell percent and utilized International Classification of Diseases codes to detect incident melanoma, which was confirmed via medical records review. Cox regression models were used to approximate hazard ratios (HRs) and 95% CIs.
The results revealed that after an average follow-up of 3.2 years, 131 participants developed melanoma, with 36 participants testing positive for MBL. Moreover, the estimated 5-year cumulative incidence of melanoma among those with and without MBL was reported as 3.4% and 2.0%, respectively. After adjustment for age, gender, and history of previous melanoma, individuals with MBL displayed a 1.86-fold risk of developing melanoma.
The researchers noted that the augmented risk continued when analysis was restricted to those without a history of melanoma (HR, 2.05; 95% CI, 1.30-3.23). Compared with individuals without MBL, individuals with LC-MBL had a 1.92-fold (95% CI, 1.29-2.87) augmented risk of developing melanoma overall and a 2.74-fold expanded risk (95% CI, 1.50-5.03) of melanoma in situ.
The researchers concluded that the presence of LC-MBL is correlated with an augmented risk of developing melanoma.
In a press release, Susan Slager, PhD, researcher at Mayo Clinic Comprehensive Cancer Center and senior author of the study, stated, “Our study is the first to show that people with this pre-cancerous stage of MBL have a 92% elevated risk of developing melanoma. The risk of melanoma is similar to what we see among people with chronic lymphocytic leukemia.”
The researchers noted that patients with CLL are encouraged to get annual skin cancer screenings by a dermatologist and to protect their skin from sun exposure to prevent melanoma.
Dr. Slager also noted, “Our findings suggest that people with the precursor MBL stage should also be more diligent about following the established guidelines for skin cancer prevention including, for example, use of sunscreen and protective clothing.”
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