The Battle of Cutaneous T Cell Lymphomas: Mycosis Fungoides Vs. Sezary Syndrome

Introduction: Mycosis Fungoides (MF) & Sezary Syndrome (SS) are two distinct extra-nodal Cutaneous T Cell Lymphomas (CTCL), which are a subtype of Non-Hodgkin's Lymphoma (NHL). Although belonging to the same entity, its presentation varies drastically. Early stage of MF is limited to the skin and whereas advanced-stage disease can involve lymph nodes, blood, & visceral organs, whereas SS involves the blood, lymph nodes, and skin. The aim of this retrospective analysis is to study the variance in the epidemiology and prognosis of MF and SS. Method: The data was collected from Surveillance, Epidemiology and End Result database Research Plus Data, 17 Registries, Nov 2022 Sub (2000-2020). We extracted Mycosis Fungoides and Sezary Syndrome cases diagnosed after 20 years of age, with Lymphoid neoplasm recode 2(b)2.1.1 and 2(b)2.1.2. The analysis was stratified based on age, sex, racial incidence rates, & survival curves based were compared, using the Log-rank test (GraphPad Prism). Results: 8853 cases of MF were identified between 2000-2020. The median age of diagnosis was 60 years. Of the affected individuals, 57.59% were males and 42.40% were females. The incidence of MF, per 1,000,000 population, in 2000 was 6.1 & 6.05 in 2020. 62.45% were whites, 13.75% were blacks, 6.98% were Asians/Pacific Islanders, 0.42% were American Indians/Alaskan Natives, & 11.64% were Hispanics. 5.2% of patients had localized disease, 8.38% patients had regionall disease, & 1.34% had the evidence of distant metastasis. vs. 307 cases of SS were identified between 2000-2020. The median age of diagnosis was 71 years. Of the affected individuals, 56.35% were males and 43.64 were females. The incidence rate of SS, per 1,000,000 population, in 2000 was 0.17 & 0.28 in 2020. 69.70% were whites, 14.00% were blacks, 2.28% were Asians/Pacific Islanders, 0.65% were American Indians/Alaskan Natives, & 12.70% were Hispanics. 46.24% of patients had localized disease, 38.11% patients had regional disease, & 16.61% had the evidence of distant metastasis. Survival analyses were compared for the general population & further stratified based on races, between MF & SS. The median of survival (mOS) was 238 months for MF & 39 months for SS ( p<0.0001, Hazard Ratio (HR) 0.2215, Confidence Interval (CI) 0.1649 to 0.2975.) Conclusion: When the subtypes of CTCLs, MF & SS, were compared, prevalence of MF was significantly more than SS. Incidence of MF somewhat stayed the same in 20 years vs SS showed an uptrend. Median age for diagnosis was higher SS (71 years) vs. SS(60 years). Both showed a strong predilection towards males. The most commonly affected race for both, was seen in Whites & the least was for American Indians/Alaskan Natives. Survival for MF(238 months) was significantly higher than SS (39 months). Although rarer of the two CTCL, SS has a poorer prognosis. With this retrospective study, our aim was to understand the epidemiology of the two CTCLs, as with the newer treatment options for these diseases like Romidepsin and Brentuximab Vedotin, it would be interesting to do a follow-up study on the epidemiological variability & survival, for these rare hematological malignancies.