Ethnicity Matters When Comparing Overall Survival for Patients Diagnosed with Follicular Lymphoma

Background

Follicular lymphoma (FLy) is one of the most common subtypes of Non-Hodgkin Lymphomas (NHL) (Cancer EpidemiolPMC4323749). In prior studies, better progression-free survival has been noted in Hispanics (HI), however, further characterization of this ethnic minority needs to be addressed (Ann Lymphoma PMC5877479). This result is consistent with previous research explaining the development of NHL as an heterogeneous process where unique outcomes for races have been noted (Cancer PMID: 22434428). This is the first combined statewide population-based study of Texas (TX) and Florida (FL) evaluating ethnic differences for HI vs Non-Hispanics (NH) comparingdemographics, socioeconomic, clinical and survival patterns of patients diagnosed with FLy. The value of using these states relies on the fact that the percentage of HI in TX and FL are 39.7% and 26.4%, respectively (US Census 2020).

Material and Methods

This is a retrospective analysis of patients diagnosed with FLy recorded in the Texas Cancer Registry and the Florida Cancer Data System from 2006-2017. Inclusion criteria was histopathologic proven FLy. Patients were divided into HI and NH for comparison. Standard demographic, socioeconomic, clinical, and survival variables were reviewed. All statistical testing was determined using Fisher's Exact test, Pearson's Chi-square test, T-test or Wilcoxon test, as appropriate. Survival time was measured using the day of diagnosis to last date of follow up or death. Survival distribution were calculated based on Kaplan-Meier curves.

Results

From 2006-2017, 20,497 patients (HI n=3,176, NH n=17,321) were diagnosed with FLy (Table 1, Table 3). In TX, the median age at diagnosis for HI was 60 years (y) vs 64 y for NH [p-value <0.001]. In FL, it was 62 y and 67 y, respectively [p-value <0.001]. In both states, female sex predominated for HI and NH. In TX, the bracket of poverty index that prevailed for HI was 20-100% while for NH was 10-19.9% [p-value <0.001]. In FL, the largest number of HI and NH were in the 10-19.9% bracket [p-value <0.001]. In TX, both HI and NH were more likely be with government-sponsor insurance, however, up to 15% of HI did not have insurance vs 4% in NH [p-value <0.001]. This was also the case in FL, however their number of uninsurance corresponded to 6% and 2% respectively.

In TX, the largest number of HI and NH patients were diagnosed at stage III-IV with 49% and 42% respectively [p-value <0.001]. In FL, for these stages it corresponded to 43% and 37% for HI and NH [p-value <0.001]. In TX, treatment at diagnosis showed a similar pattern for HI and NH, choosing mainly no treatment followed by multiple chemotherapy agents [p-value <0.001]. In FL, this trend was also seen. In both states and for HI and NH, most of the patients did not undergo transplant or radiation.

In TX, the median overall survival for HI was 9.2 y vs 8.6 y for NH; the survival probability at 2, 5 and 10 y for HI corresponded to 0.835, 0.701 and 0.453, while for NH it was 0.850, 0.703 and 0.354, respectively; and the overall survival probability at 10 y had no statistically significant difference [p-value 0.44] (Table 2, Graph 1). In FL, the median overall survival for HI was not reached vs NH at 10.1 y; the survival probability for HI at 2, 5 and 10 y was 0.871, 0.777 and 0.601, while for NH it was 0.845, 0.709 and 0.506, respectively; and the overall survival probability at 10 y was statistically significant [p-value <0.0001] (Table 4, Graph 2).

Conclusions

This large two statewide population-based study identified statistical differences in oncological outcomes comparing HI and NH in patients diagnosed with FLy. HI diagnosed with FLy have higher survival at 10 y, and this difference was statistically significant in FL. Moreover, statistical significance was noted in demographic, sociodemographic and disease characteristics. Additional research should be carried out to identify the variables that drive this difference since advance stage, lack of insurance or treatment at diagnosis do not seem to be influencing it. There may be a combination of lifestyle factors (alcohol, cigarette, diet, other), occupational hazards, autoimmune diseases or protective mechanisms, infectious diseases exposures and unique epigenetic interactions that may explain why HI live longer when diagnosed with FLy.

Figure 1

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Figure 1

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