Individuals diagnosed with low-count monoclonal B-cell lymphocytosis (LC-MBL) had about a two-fold increased risk for melanoma, similar to that seen in individuals with chronic lymphocytic leukemia (CLL), a study published in the Journal of Clinical Oncology found.
Melanoma is one of the most common second primary malignancies diagnosed in patients with CLL. In this study, Susan L. Slager, PhD, of Mayo Clinic in Rochester, Minnesota, and colleagues sought to determine if the risk for developing melanoma among patients with CLL extended to people with the precursor condition MBL.
“The biologic link between melanoma and CLL may include genetic correlation of inherited variants, similarities of acquired variants, and immune dysfunction,” Dr. Slager explained. “Historically, LC-MBL was thought to be an aging phenomenon with no clinical relevance. But our research, including the results herein, support the concept that low-count MBL does affect one’s clinical health.”
To explore whether there was an association between MBL and melanoma, Dr. Slager and colleagues used data from the Mayo Clinic Biobank to identify participants aged 40 or older who had no prior history of hematologic malignancies and had biospecimens available for screening. Specimens were screened for MBL and classified as either LC-MBL if fewer than 85% of B cells were clonal B cells, or high-count (HC-MBL) if more than 85% of B cells were clonal B cells.
Of the 7,334 screened samples, 1,151 (15.7%) were positive for MBL; 95.4% of these were classified as LC-MBL.
With a median follow-up of 3.2 years, 131 individuals developed melanoma; 36 of these individuals were positive for MBL. Individuals without MBL had a five-year estimated cumulative incidence of melanoma of 2.0% compared with 3.4% in those with MBL. Rates were similar when the analysis was restricted to only those individuals with LC-MBL.
After adjusting for age, sex, and history of previous melanoma, having MBL was associated with a 1.86-fold increased risk for melanoma (95% CI 1.25-2.78; p=0.002). When restricted to those without a history of melanoma, the risk increased to 2.05 (95% CI 1.30-3.23; p=0.002).
Compared with individuals without MBL, those with LC-MBL had a 1.92-fold increased risk for developing melanoma overall (95% CI 1.29-2.87; p=0.001), a non-significant 1.49-fold increased risk for invasive melanoma (95% CI 0.88-2.53; p=0.14), and a 2.74-fold increased risk for developing melanoma in situ (95% CI 1.50-5.03; p=0.001).
“Individuals with LC-MBL should follow the recommended guidelines for skin cancer prevention,” Dr. Slager said. “However, most individuals with LC-MBL don’t know they have LC-MBL. The ones who do know probably know because of an incidental finding through something like preoperative surgical testing.”
The study had several limitations, including that most patients (96.3%) were of European ancestry, which limits generalizability. According to Dr. Slager, another limitation was the inability to directly account for sun exposure, an important risk factor for melanoma.
“Using a proxy for sun exposure, our findings held, but it would still be better to actually have this risk factor data measured,” Dr. Slager said.
Finally, the study did not evaluate the effect of HC-MBL on risk of incident melanoma because only 53 patients had HC-MBL.
Dr. Slager said current standards do not recommend routine screening for MBL. Instead, “our research findings for MBL support following established guidelines for all individuals, such as skin cancer prevention or reducing infection risks by getting vaccinated and hand washing. Further, at this time, no known prevention strategies exist for MBL or for MBL progression.”
Any conflicts of interest declared by the authors can be found in the original article.
Reference
Vallejo BA, Ansari A, Parikh SA, et al. Risk of incident melanoma among individ-uals with low-count monoclonal B-cell lymphocytosis [published online ahead of print, 2024 September 4]. J Clin Oncol. doi: 10.1200/jco.24.00332.
