Obese Patients Have Improved Survival Following Autologous Hematopoietic Stem Cell Transplantation
Authors: Duong Hien K. , Koo Anna , Rybicki Lisa , Copelan Ed , Kalaycio Matt , Sobecks Ronald , Dean Robert M , Hill Brian T. , Ondrejka Sarah L. , Abounader Donna M , Pohlman Brad , Bolwell Brian J. 
Published: October 2019

Abstract
Abstract 1989
High-dose chemotherapy followed by autologous stem cell transplant can improve long-term outcome of patients with hematologic malignancies. Outcomes following transplant are variable. Obesity has implications for stem cell mobilization, chemotherapy administration, and medication dosing. We analyze the impact of obesity on transplant outcomes including neutrophil recovery, platelet recovery, length of hospital stay, and survival.
From 1/2004 to 12/2009, 573 patients underwent autologous stem cell transplant. From these patients, 17 were excluded due to incomplete data. Of the remaining 556 patients, the median age was 53 years, and 346 (62%) were male. The diagnoses were 286 (51%) non-Hodgkin lymphoma, 161 (29%) multiple myeloma, 91 (16%) Hodgkin lymphoma, and 18 (3.2%) other. A majority of these patients (93%) had received 3 or less prior chemotherapy regimens. Most patients (76%) had not received prior radiation therapy. Most patients had chemosensitive disease (92% were in complete or partial remission) at time of transplant. For stem cell mobilization regimen, 376 (68%) received chemotherapy and G-CSF, 176 (32%) received G-CSF alone, and 4 (<1%) received G-CSF and Plerixafor. For a preparative regimen, 360 (65%) received busuflan/etoposide/cyclophosphamide, 125 (23%) received melphalan, and 71 (13%) received busulfan/cyclophosphamide.
Patients were categorized into four groups based on the body mass index (BMI): underweight (BMI<18.5), normal (18.5–24.9), overweight (25.0–29.9), or obese (≥30.0). Using these definitions, there were 5 (1%) underweight, 133 (24%) normal, 188 (34%) overweight, and 230 (41%) obese patients. Underweight and normal were combined into a single group due to the small number of underweight patients. Baseline and transplant characteristics of these patients are listed in Table 1. Variables were compared among BMI groups using the Chi-square test (categorical variables), Kruskal-Wallis test (continuous variables), or log-rank test (survival). Cox proportional hazards analysis was used to identify prognostic factors for survival.
On univariable and multivariable analyses, obese patients demonstrate better survival than those who are not obese (hazard ratio 0.73, P=0.026; Figure 1).
In conclusion, obesity has no impact on neutrophil or platelet recovery, length of transplant hospitalization, or 100-day mortality. Obese patients appear to have improved overall survival. The reasons for this are unclear, but may have to do with higher total dose of chemotherapy for the preparative regimen. Although obesity is associated with many co morbidities and possibly more aggressive disease, these patients do not have cancer cachexia and may have other protective benefits.
Table 1. Patient and transplant characteristics according to BMI Underweight/  Normal N = 138 Overweight  N = 188 Obese N = 230 Variable N (%) N (%) N (%) P-value Gender     Male 63 (46) 136 (72) 147 (64) <0.001     Female 75 (54) 52 (28) 83 (36) Age, years     Median (range) 50 (20–74) 55 (20–73) 54 (19–75) 0.013 Number of prior chemotherapy regimens     ≤ 3 130 (94) 177 (94) 212 (92) 0.65     >3 8 (6) 11 (6) 18 (8) Prior radiation therapy     Yes 38 (28) 45 (24) 53 (23) 0.61     No 100 (72) 143 (76) 177 (77) Diagnosis     NHL 74 (54) 98 (52) 114 (50) 0.025     MM 28 (20) 53 (28) 80 (35)     HL 33 (24) 30 (16) 28 (12)     Other 3 (2) 7 (4) 8 (4) Disease status at transplant     CR/PR 120 (87) 172 (91) 217 (94) 0.048     Active disease 18 (13) 16 (9) 13 (6) Mobilizing regimen     G-CSF+chemotherapy 106 (77) 126 (67) 144 (63) 0.05     G-CSF alone 32 (23) 61 (32) 83 (36)     G-CSF + Plerixafor 0 (0) 1 (0.5) 3 (1) Preparative regimen     Bu/VP/Cy 94 (68) 128 (68) 138 (60) 0.22     Melphalan 30 (21) 34 (18) 61 (27)     Bu/Cy 14 (10) 26 (14) 31 (13) CD34+ dose, × 106/kg     Median (range) 6.19 (2.11–47.97) 5.67 (2.06–65.18) 7.01 (1.62–51.90) 0.21 Days to ANC > 500     Median (range) 11 (9–13) 11 (9–17) 10 (9–15) 0.36 Days to platelet > 20,000     Median (range) 14 (6–129) 14 (5–432) 14 (3–46) 0.48 Length of hospital stay     Median (range) 21 (13–30) 20 (13–74) 20 (12–37) 0.08 100-day mortality     Yes 9 (7) 9 (5) 4 (2) 0.06     No 129 (93) 179 (95) 226 (98)
Figure 1: Survival outcomes according to BMI Figure 1:. Survival outcomes according to BMI

Disclosures:
No relevant conflicts of interest to declare.