The Role of Ethnicity in Hepatosplenic T-Cell Lymphoma: A Retrospective Survival Analysis in Texas

Background

Hepatosplenic T-Cell lymphoma (HSTCL) is an aggressive type of lymphoma with extremely low incidence. It has a high fatality rate with a 5-year overall survival (OS) of <10% (Am J Surg Pathol, PMID: 26872013). Although there is no therapy that has proven to produce sustained remission, recent studies suggest improvement in outcomes with allogeneic stem cell transplant (allo-SCT) (Leukemia, PMID: 25234166). Clinical characteristics and therapeutic outcomes have been previously reported; however, documentation of outcomes in minorities such as Hispanics (HI) are lacking. Given the growth of the HI population in the US it is imperative to understand the difference in outcomes and patterns of care (CA Cancer J Clin, PMID: 30285281). The present study aims to fill this gap in the literature; therefore, the present population-based study evaluates the impact of ethnicity in clinical outcomes for HSTCL.

Material and Methods

We retrospectively searched for cases of HSTCL recorded in the Texas Cancer Registry. Inclusion criteria included and established pathologic diagnosis of HSTCL using the International Classification of Diseases for Oncology Third Edition (ICD-O-3) code list. Patients were divided between HI and non-Hispanics (NH). Demographic, socioeconomic, clinical and survival outcomes were recorded. Statistical analysis included Fisher's Exact test, Pearson's Chi-square test, T-test or Wilcoxon test. Survival analysis was calculation in years from date of primary diagnosis to date of death or last date of follow up. Survival distributions were described with Kaplan-Meier curves, and long rank testing was used to assess significance of variation in median survival with ethnicity. All statistical testing was two-sided with a significance level of 5%. The R language [R Core Team (2013). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria] was used throughout.

Results

From 2006-2016, a total of 25 patients were diagnosed with HSTCL; 23 (92%) were NH and 2 (7%) were HI [<0.0001]. The median age at diagnosis was 46 for HI and 48 for NH. It was predominantly seen in males for both HI and NH. The patients mostly self-identified as white (HI: n=2, Nh: n=16), and there were 7 (30%) NH patients that self-identified as black. For HI, one patient was in the bracket of poverty indicator of 10-19.9% and the other one was in the 20-100%; for the NH patients the bracket that prevailed was 10-19.9% [p-value 0.56]. Both HI patients had private insurance (PI); insurance status on NH patients included 7 (33.3%) with PI, 5 (23.8%) with Medicare, and 7 (33.3%) was unknown [p-value 0.64]. The majority of HI and NH patients were located in the metropolitan, non-border area.

Stage at diagnosis for NH was mostly III-IV; one HI had a stage III-IV HSTCL and the other was unstaged [p-value 1.0]. From a therapeutic standpoint, the majority of HI and NH patients received chemotherapy, with 13 patients (HI: n=2, NH: n=11) receiving multiple agents as first-line therapy [p-value 0.84]. From the two groups, only 3 (13%) NH patients underwent allo-SCT [p-value 0.014]. The majority of HI and NH did not undergo radiation (Figure 1A).

The median overall survival was 0.5 years in HI and 0.6 in NH. The survival probability at 2 years for HI and NH was 0.5 (CI=0.16, 1) and 0.29 (CI=0.15, 0.56) respectively; at 5 years for HI was 0.5 (CI 0.16, 1) and for NH was 0.23 (CI=0.10, 0.51) (Figure 1B). The overall survival probability at 10 years was not statistically different for HI vs NH [p-value 0.53] (Figure 1C).

Conclusions

Survival analysis shows that HSTCL is usually fatal with a median overall survival of less than a year, and no difference in survival probability at 10 years for both HI and NH. The majority of patients in our study were non-Hispanic white males. A significant finding was that NH patients had access to allo-SCT as opposed to the HI patients. No statistically significant difference in survival was noted depending on the insurance or poverty levels. No other demographics or sociocultural variables seemed to have an impact in outcomes. The main limitation of our study is our sample size that limits generalizability and power of our statistical analysis. Further studies using multiple cancer registries are warranted to assess the clinical characteristics and survival outcomes in HI with HSTCL.

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