Impact of Pretreatment Serum Beta-2 Microglobulin in Predicting Response to Chemotherapy in Lymphoma: Systematic Review and Meta-analysis

BACKGROUND: Serum beta-2 microglobulin (sB2M) has been identified as a marker of clinical outcomes in several cancers. However, its predictive value in the context of chemotherapy has not been systematically studied, and the exact mechanism explaining increased sB2M levels in cancers remains controversial. OBJECTIVES: This systematic review was conducted to provide a better understanding of the role of sB2M in lymphoma. DATA SOURCES: We systematically searched PubMed and Google Scholar for relevant studies. STUDY SELECTION: After duplicate removal, 181 records were screened. Following a review of titles, abstracts, and full-texts, 4 studies fulfilled the inclusion criteria and were included in the analysis. RESULTS: This meta-analysis included four studies. In the entire cohort, 39.9% of patients achieved complete remission after chemotherapy. Non-Hodgkin lymphoma patients with high pretreatment sB2M levels (>2.5 mg/L) were more likely to have a poor response to chemotherapy (odds ratio = 6.45, 95% confidence interval [4.21, 9.89]). CONCLUSIONS: Non-Hodgkin lymphoma patients with higher pretreatment sB2M levels were more likely to have a poorer response to chemotherapy. The findings of this study suggest that high sB2M levels are independent of tumor growth, high turnover, and high division rates. This is consistent with the hypothesis that elevated sB2M levels in NHL may be due to structural defects in B2M molecules. These structural defects prevent the proper conformation of human leukocyte antigen class I and increase the immune escape of cancer cells, thereby rendering them less responsive to treatment.