Impact of body mass index (BMI) on clinical and toxicity outcomes in patients with relapsed metastatic germ-cell tumor (GCT) undergoing high-dose chemotherapy (HDCT) with peripheral blood stem cell transplant (PBSCT).

Abstract

517 Background: ASCO guidelines recommend full weight-based dosing of cytotoxic chemotherapy for all pts regardless of BMI. The regimen for HDCT in relapsed GCT at our institution uses actual body weight (ABW) dosing for carboplatin and etoposide. There is limited data on the implications of using ABW to dose HDCT in pts with GCT. We describe clinical and toxicity outcomes based on pre-transplant BMI in pts with relapsed metastatic GCT undergoing HDCT with PBSCT. Methods: The prospectively maintained Indiana University testicular cancer database was queried for pts with relapsed GCT treated between 1990-2023 with HDCT and PBSCT. Pts were classified by pre-transplant BMI as BMI <25 (normal weight), BMI 25-29.9 (overweight), or BMI ≥30 (obese). Grade 3 or higher (≥G3) toxicities were assessed using CTCAE. Comparisons between groups were done using Chi-square tests for categorical variables or Wilcoxon test for continuous variables. Kaplan-Meier methods were used to analyze progression-free survival (PFS) and overall survival (OS). The log rank test was used to compare groups. Results: 597 pts met inclusion criteria. Median age at initiation of HDCT was 32.4 (range, 16.7-70.1). Primary site was testis in 85%, retroperitoneum in 8%, and mediastinum in 7%. 76% of patients had non-seminoma. IGCCCG risk was good in 40%, intermediate in 11%, and poor in 48%. HDCT was the 2nd line treatment for 83% of pts and ≥3rd line for 17%. 90% of pts completed both cycles of HDCT. 202 pts (34%) had normal BMI, 223 (37%) were overweight and 172 (29%) were obese. Median carboplatin dose was 2100mg/m2 and median etoposide dose 2250mg/m2 for all pts in both cycles. 63% of obese pts experienced at least 1 G≥3 non-hematologic adverse event vs. 43% of overweight pts vs. 44% of pts with normal weight (p=0.0001). The rate of G≥3 renal toxicity was higher in obese pts at 17% vs. 7% in overweight pts vs. 5% in normal weight pts (p= 0.0001). G≥3 GI toxicity was higher in obese pts at 50% compared to 36% in overweight pts and 37% in normal weight pts (p=0.0079). The table lists toxicity and survival outcomes by pre-transplant BMI. Conclusions: Obese pts with relapsed GCT undergoing HDCT had higher incidence of overall G≥3 toxicity specifically renal and GI toxicity. Treatment-related mortality and survival was not impacted by differences in BMI. [Table: see text]