Demographic Differences in the Treatment and Mortality of Lymphoplasmacytic Lymphoma in Texas: Does Ethnicity Play Any Role?

BACKGROUND:

Social determinants and demographics exert an overwhelming influence on the health of the individual and overall population health (J Am Geriatr Soc. PMID: 28369694).The Hispanic paradox has been well characterized, demonstrating that although Hispanic patients (HisP) have higher disability, depressive, metabolic, and inflammatory risk when compared to non-Hispanic (nHisP), they continue to live long lives (J Health Soc Behav. PMID: 31771347). The characterization of these differences in hematology has not been well documented. This study seeks to characterize Lymphoplasmacytic lymphoma (LPL). LPL is a rare lymphoma of B-cell origin demonstrating an incidence of 1000 to 1500 new cases per year in the United States (Hematol Oncol Clin North Am, PMID: 31229160). Epidemiological research is not well documented in this lymphoma subtype, especially regarding the HisP. Given that Texas has the second highest state with HisP in the country (US Census Bureau), we studied the demographics of this disease and specifically researched the demographics, treatment patterns and survival between HisP and nHisP in Texas.

METHODS:

This is a retrospective study of a cohort of patients diagnosed with lymphoma (Hodgkin and Non-Hodgkin) from the Texas Cancer Registry (TCR) database. Patient's included were those >18 years of age during 2006-2016 and this study focused on the LPL subset. Standard demographic variables collected include gender, race, ethnicity, birthplace, occupation, dates at diagnosis and death, primary payer at diagnosis, subtype of lymphoma, stage, type of treatment, poverty index, and vitality status among others. The significance of variation in the distribution of categorical outcomes with ethnicity (HisP, nHisP) was assessed with Fisher's Exact tests or Pearson's Chi-square tests as appropriate; age was assessed with T-tests or Wilcoxon tests as appropriate. Survival time was measured in years from date of primary diagnosis to date of death. Survival distributions were described with Kaplan-Meier curves and significance of variation in median survival with ethnicity was assessed with log rank testing. All statistical testing was two-sided with a significance level of 5%.

RESULTS AND DISCUSSION:

Out of 490 patients diagnosed with LPL, 64 were HisP and 426 nHisP. Of this population, the HisP had a higher percentage of patients at the higher end of the poverty index (42.4% to 20% with p value <0.001) and higher rates of being uninsured or on Medicare (51.6 to 43.4% with p value <0.001). There were no statistically significant differences in the staging at the time of diagnosis between the two groups, mostly III/IV (HisP 65.6% to nHisP 62% P value 0.387). Treatment modalities differed slightly in that the nHisP populations were more likely to receive beam radiation than the HisP (3.4% to 0, P value 0.005) but overall chemotherapy differences were not statistically significant. The median survival time in years for HisP and nHisP was 6.8 and 7.6 respectively, and the overall survival probability was not significantly different with a P value of 0.59. The survival probabilities at 2, 5 and 10 years between HisP and nHisP were respectively, 0.657 with Confidence interval (CI)[0.545,0.792], 0.573 CI [0.455,0.722], 0.448 CI [0.32,0.627], compared to 0.766 CI [0.723,0.811], 0.620 CI [0.566,0.68], 0.129 CI [0.042,0.389].

CONCLUSION:

In this study we show that in Texas, for those diagnosed with LPL, there is a statistically significant difference in the rates of poverty and insurance when comparing Hisp to nHisP. While this is true, there is no clear statistically significant difference in overall treatment or survival probability, which is consistent with the Hispanic paradox. Due to the rarity of this disease, the population size is limited which may skew the data. More research is needed in order to further characterize the differences between these two populations and determine what can be done to narrow these differences.

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