What Is the Appropriate Dose Attenuation System of RCHOP for Elderly DLBCL Patients? - A Single Institutional Analysis in 115 Cosecutive Patients From Japan -
Authors: Tanimura Akira , Hirai Risen , Sato Atsushi , Nakamura Miki , Takeshita Masataka , Hagiwara Shotaro , Miwa Akiyoshi 
Published: October 2019

Abstract
Abstract 3639

Background:
The combination therapy of RCHOP [rituximab (R), cyclophosphamide (CY), doxorubicin (DOX), vincristine (VCR), and prednisone (PSL)] is a standardized treatment for diffuse large B-cell lymphoma (DLBCL). However, its clinical outcome is worse in elderly patients because of comorbidities, age-related decrease in organ function, and impaired drug metabolism. If possible, the dose of RCHOP in elderly patients and patients with comorbidities should be adjusted appropriately. Since 2005, we have used a unified dose attenuation system for RCHOP according to the age and comorbidities of patients. This study retrospectively verified this system.

Patients/Methods:
We analyzed 115 consecutive DLBCL patients treated at our institute from September 2001, when rituximab was approved in Japan, to December 2010. From September 2001 to August 2005, 33 patients received dose adjustment of RCHOP according to the physician's discretion (PHY group). From September 2005, 82 patients received RCHOP according to the unified dose attenuation system (UNI group). In the UNI group, patients younger than 60 years received the standard RCHOP dose [R, 375 mg/m2; CY, 750 mg/m2; DOX, 50 mg/m2; VCR, 1.4 mg/m2 (max 2.0 mg/body); PSL, 100 mg/m2]. In patients older than 60 years, the doses of CY, DOX, VCR, PSL, and R were attenuated as shown in Table 1. In addition to age, the doses of CY, DOX, and VCR were adjusted according to organ functions (Table 2). The two groups were compared statistically.

Results:
The median age of patients was 70 years (range, 38–91), with 70.4% of patients classified as stage III or IV DLBCL, 40.4% with an international prognostic index (IPI) score of 0–2, and 70.2% with a ECOG performance status (PS) of 0 or 1. Low serum albumin levels (under normal range) were observed in 50.5% patients, and a high Charlson comorbidity index (CCI) score of >1 was found in 58.3%.
The characteristics of the patients in the two groups were almost similar. The UNI system was completed in 94% of patients. The complete response (CR) rate was 63% in all patients (UNI group, 73%; PHY group, 39%; P = 0.0006). Univariate analysis revealed that better prognostic factors for CR were a low IPI score, better PS, and the UNI group. In the multivariate analysis, only the UNI group was a significantly better prognostic factor for CR. With a median follow-up of 26 months, the 5-year event-free survival (EFS) and overall survival (OS) were 39.3% and 68% in all patients, 43% and 72% in the UNI group, and 27% and 59% (5-year EFS; P = 0.0083, 5-year OS; P = 0.16) in the PHY group, respectively. Multivariate analysis showed that better prognostic factors for EFS were a low IPI score, a low CCI score, and the UNI group, and that for OS were low IPI and low CCI scores. In elderly patients aged >70 years (N = 59), the CR rates were 81% and 13% in the UNI and PHY groups, respectively (P = 0.0004), with OS in the UNI group being longer than that in the PHY group (72% vs. 59%; P = 0.02; Fig.1). In the UNI group, patient age did not affect the CR rate (<70, 71% vs. 70–79, 83% vs. >79, 79%; P = 0.56) or 5-year OS (<70, 76% vs. 70–79, 70% vs. >79, 66%; P = 0.58). The actual dose of CY, DOX, and VCR compared with the standard RCHOP dose was 64% and 26%, 63% and 16%, and 63% and 21% in the UNI and PHY groups, respectively. Disease progression during treatment, discontinuation of therapy, and death during treatment were observed in 10% and 15%, 5% and 24%, and 5% and 3% in the UNI and PHY groups, respectively.
Nineteen patients (23%) from the UNI group died over a median follow-up of 15 months, while 15 patients (45%) of the PHY group died over a median follow-up period of 29 months. Lymphoma-related deaths were 12 (14%) in the UNI group and 8 (24%) in the PHY group. Five secondary primary malignancies (SPM) were observed (1 colon cancer and 1 breast cancer in the PHY group, and 1 lung cancer and 2 myelodysplastic syndrome in the UNI group). Four deaths were related to SPM.

Conclusion:
The unified dose attenuation system determined by the patients' age and comorbidities may achieve an effective dose level and better prognosis in elderly DLBCL patients.

Disclosures:
No relevant conflicts of interest to declare.