Preoperative β2 Microglobulin Is a Prognostic Factor in Patients with Renal Cell Carcinoma and Normal Kidney Function

Gregory Palmateer,1 Eduoard H Nicaise,1 Taylor Goodstein,1 Dattatraya H Patil,1 Shreyas S Joshi,1,2 Vikram M Narayan,1,2 Kenneth Ogan,1 Viraj A Master1,2 1Department of Urology, Emory University School of Medicine, Atlanta, GA, USA; 2Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USACorrespondence: Viraj A Master, Department of Urology, Emory University, 1365 Clifton Road NE, Building B, Suite 1400, Atlanta, GA, 30322, USA, Tel +1 404-778-4898, Fax +1 404-778-4231, Email [email protected]: β 2 microglobulin is a non-glycosylated protein synthesized by all nucleated cells. It has been utilized as a tumor marker in several different malignancies, however, studies examining its role in renal cell carcinoma (RCC) are limited.Methods: Using the Emory kidney cancer database, patients with any stage or histology RCC who underwent partial or radical nephrectomy from 2014 to 2022 and had an available β 2 microglobulin within 90 days before surgery were included. Following manufacturer’s recommendation, β 2 microglobulin ≥ 2.34 mg/L was considered elevated. Patient and surgical characteristics were recorded. Kaplan Meier curves and multivariable Cox Hazards models were used to assess the association between an elevated β 2 microglobulin and overall and cancer-specific survival. Subgroup analysis was performed between patients with and without renal dysfunction (defined as an estimated glomerular filtration rate (eGFR) of ≤ or > 60 mL/min/1.73m2) and with and without metastatic disease.Results: Of 429 patients who met inclusion criteria, 178 (41.5%) had an elevated preoperative β 2 microglobulin. After adjusting for confounders, an elevated β 2 microglobulin was independently associated with worse CSS (HR 2.08 [95% CI 1.20– 3.60]; p = 0.009) and OS (HR 1.58 [95% CI 1.03– 2.41]; p = 0.035) compared to a normal β 2 microglobulin. On subgroup analysis, elevations in β 2 microglobulin levels remained significantly associated with OS and CSS in patients with normal renal function and non-metastatic disease.Conclusion: Preoperatively elevated β 2 microglobulin levels are independently associated with worse OS and CSS in patients with RCC undergoing nephrectomy. The utility of β 2 microglobulin as a prognostic indicator is most relevant for patients with normal renal function and non-metastatic disease.Keywords: β 2 microglobulin, eGFR, overall survival, cancer-specific survival, RCC