The Trend of Combined Modality Treatment and its Outcomes in Elderly Patients With Primary CNS Lymphoma: A 12-year Population-based Analysis Using Propensity Score

The addition of radiation to chemotherapy in elderly patients with primary central nervous system lymphoma (PCNSL) remains controversial. This aim of this study was to assess the trend of combined modality treatment (CMT) and compare its survival with chemotherapy alone and radiation alone in non-HIV patients.We identified 6,537 patients who received single treatment modality, CMT, or no treatment at all between 2004 and 2015 from the National Cancer Database. Factors affecting treatment selection were investigated using a logistic regression model. Annual percentage change (APC) was calculated to assess the trend of CMT use. A propensity score weighting methodology was used to compare survival outcomes.Only 12.8% of patients received CMT, and this proportion steadily declined between 2004 (17.7%) and 2015 (8.7%), with an APC of -6.0% (95%CI=-8.0 - -4.0, p-value0.001) during the 12 years. Apart from classical prognostic factors (age and comorbidities), treatment selection was significantly influenced by sex, facility type, degree of urbanization, and type of insurance. CMT had improved survival [median overall survival 19.5 months (95%CI=15.7-22.8)] compared with single-modality treatment. This effect was more prominent in the first year.Socioeconomic factors affect the selection of treatment in elderly patients with PCNSL. CMT is falling out of favor in this patient population due to the risks of neurotoxicity. Further work should focus on developing strategies that minimize toxicity and access disparities without compromising survival.