Measurable Absolute Basophil Count is Associated with Progression to Muscle Invasive Disease in Patients with High-Grade Non-Muscle Invasive Bladder Cancer

Introduction Intravesical bacillus Calmette-Guerin (BCG) is the standard adjuvant treatment for high-grade non-muscle invasive bladder cancer (NMIBC) after transurethral resection of the bladder tumor (TURBT). Despite this standard of care - 40% of patients experience a recurrence and - 15% progress to muscle invasive disease. Tumors with Th1-polarized lymphocytic infiltrate in the tumor immune microenvironment may have more favorable response to BCG compared to Th2- polarized tumors. Since basophils have a promoting role in Th2-polarization, we explored the association of blood basophils on the outcome of patients with high-grade NMIBC receiving BCG instillations. Methods Clinical data and pre-operative complete blood count (CBC) results from patients with high-grade NMIBC (Ta, CIS and T1) who received BCG instillations at the Vancouver Prostate Centre (VPC) during years 2011 – 2018 were collected. Absolute basophil count (ABC) was correlated with response to BCG, disease recurrence and progression to muscle invasive disease. Results A total of 174 patients with primary high grade NMIBC treated with BCG at VPC were identified. Pre-operative complete blood count (CBC) data were available from 161 patients. After the initiation of BCG therapy 40% of patients developed recurrent tumors and 13% progressed to muscle invasive disease. ABC was measurable (³ 0.1 × 103 cells /µl) in the blood of 33 (19%) patients of whom 19 (58%) recurred. A total of 95% of recurrent tumors with measurable ABC were considered BCG-unresponsive. In Kaplan-Meier analysis measurable ABC was associated with tumor recurrence (p = 0.024) and progression to muscle invasive disease (p = 0.00015). In multivariate cox-regression analysis measurable ABC was considered an independent prognostic factor for progression to muscle invasive disease (HR 2.9, 95% CI:1.038 – 8.535, p = 0.042). Conclusions Measurable blood absolute basophil count may have a prognostic impact for patients with high-grade NMIBC. Further studies with larger patient cohorts are needed to confirm these preliminary results.