Increased Incidence of Melanoma, Prostate, Lung, Bladder, Renal and Thyroid Cancer after Diagnosis of Primary Cutaneous B-Cell Lymphoma: A SEER Database Analysis

Background: Primary cutaneous B-cell lymphomas (PCBCLs) are a subset of non-Hodgkin lymphomas originating in the skin. The risk of developing other malignancies in PCBCL patients is not known. We evaluated the risk of developing a second primary malignancy after a PCBCL diagnosis. Methods: We utilized the surveillance, epidemiology, and end results (SEER-17) data registry of 9,208,295 patients from 2000-2020 to generate a cohort of 5,435 patients with PCBCL to identify patients at risk for a second primary malignancy. Relative risk was calculated by using the Standardized Incidence Ratio (SIR), defined as the ratio between observed cases (O) and expected cases (E) of malignancies (SIR = O/E). Statistical significance was established based on 95% confidence intervals (CI). Results: Of the 5,435 patients with PCBCL, 847 (16%) received diagnoses of a second malignancy, identifying a higher risk than the general population (SIR, 1.54; 95% CI, 1.43-1.64). Males had a higher chance of developing prostate cancer (SIR, 1.29; 95% CI, 1.07-1.54), melanoma (SIR, 1.49; 95% CI, 1.03-2.09), and bladder cancer (SIR, 1.42; 95% CI, 1.01-1.94). Females were more predisposed to cancers of the lung (SIR, 1.69; 95% CI, 1.25-2.24), thyroid (SIR, 3.06; 95% CI, 1.63-5.23), and kidney (SIR, 2.13; 95% CI 1.06-3.81). For males with PCBCL, there was an increased risk of prostate cancer in patients 60-69 (SIR, 1.53; 95% CI, 1.14-2.02). For females, there was an increased risk of lung cancer in patients over 70, especially in the age group of 70-79 (SIR, 1.84; 95% CI, 1.12-2.84). For cutaneous melanoma, bladder, renal, and thyroid cancer, there was no age group identified to be at a significantly greater risk. Prostate cancer risk was increased within the first year (SIR, 2.09; 95% CI, (1.28 - 3.23) and between 5-10 years after PCBCL diagnosis (SIR, 1.45; 95% CI, 1.04-1.97) .For males, melanoma and bladder cancer were associated with an increased risk between 1-5 years after PCBCL (SIR, 1.91; 95% CI, 1.09-3.11 and SIR, 1.7; 95% CI, 1.01-2.68). Females were at the highest risk of developing thyroid cancer within the first year of PCBCL diagnosis (SIR, 21.11; 95% CI, 10.12-38.83) and lung cancer 1-5 years after PCBCL diagnosis (SIR, 1.7; 95% CI, 1.04-2.62). For renal cancer, there was no latency identified carrying an increased risk. Conclusion: These data, should inform screening strategies for melanoma, prostate, bladder, lung, renal, and thyroid cancer in patients with PCBCL. Males 60