Incidence of skin cancer among patients with Waldenstrom macroglobulinemia: Analysis of the SEER database (2000-2019).

e18893 Background: The association between non-Hodgkin lymphoma, including chronic lymphocytic leukemia, and aggressive skin cancers is well established. We studied the incidence of melanoma and non-melanoma skin cancers (NM) skin malignancies (SM) among patients with Waldenstrom macroglobulinemia (WM). Methods: We used the SEER 17 registry to identify adult [Age > 20] patients(pts) with an index diagnosis (dx) of WM between 2000- 2019. We included ICD-O-3 codes 9671/3 (Lymphoplasmacytic lymphoma) and 9761/ (Waldenstrom macroglobulinemia) to identify index dx. Only first of the two codes was used if both were mentioned for same pt. We excluded patients with diagnosis made from death certificate or autopsy. We used ICD-O-3/WHO 2008 codes assigned to melanoma of skin and other NM SM to identify subsequent diagnosis ( > 2months after index diagnosis) of SM excluding basal cell and squamous cell cancers. SM were categorized using ICD-O-3 codes for histology. Follow up period was till December 2019. Data variables and standardized incidence ratio [SIR] for SM were obtained with multiple primary SIR analyses using SEER Stat v 8.4.0.1 software. Kaplan Meier method was used to estimate overall survival (OS) using R 4.2.2. Results: We identified 8099 patients with WM of which 68 patients (0.84%) had a subsequent dx of SM. WM and SM were diagnosed at median (IQR) ages of 69 (60-77) and 74 (67-81), with a median gap of 52 (30-95) months. Majority of WM survivors with SM were males (51 or 75%), white (100%) and older than 60 years of age (72%) at WM diagnosis. Almost half of the patients who developed SM underwent chemotherapy for WM (n = 35, 45%). The overall risk of developing SM was significantly higher in WM patients as compared to the general population [SIR (95%CI) = 1.34 (1.01-1.74) (p < 0.05) for melanoma and 2.85 (1.52-4.87) (p < 0.05) for NM]. Eleven different types of histology for SM were noted, with malignant melanoma, NOS (n = 30, 44%) and Merkel cell carcinoma (n = 7, 10%) being the most common melanoma and NM subtype (Table). The median survival after SM dx was 68 (55-NA) months. Conclusions: Patient with WM had higher risk of SM (melanoma and NM skin cancers, excluding basal cell and squamous cell cancers) compared to the general population. This study highlights the need for screening and counseling for skin cancers in WM patients in routine clinical practice. [Table: see text]