Retrospective Study of the Optimal CHOP Dose for Elderly Patients with Diffuse Large B-Cell Lymphoma

Background: Diffuse large B-cell lymphoma (DLBCL) is the most common type of malignant lymphoma, and the number of elderly patients with DLBCL is increasing. While rituximab plus CHOP (R-CHOP) therapy is considered as the standard first-line treatment for DLBCL, elderly patients are often frail and unable to tolerate the standard dose of R-CHOP. Fifteen years ago, we conducted a prospective study to investigate optimal reduced doses of CHOP therapy for patients aged 65-79 years and those older than 79 years. We concluded that 5/6 (83%) and 7/12 (58%) doses of standard CHOP are effective and tolerable for these two age groups, respectively (Mori M, et al. Leuk Lymphoma. 2001;41:359-66). Since then, we have applied this strategy with the standard dose of rituximab. To evaluate the efficacy and tolerability of reduced R-CHOP therapy for elderly patients, we performed a retrospective analysis.

Methods: We reviewed medical records of patients aged 65 years or older with newly diagnosed DLBCL, who underwent R-CHOP therapy from August 2010 to December 2013. Intravascular large B-cell lymphoma and primary central nervous system lymphoma were excluded from this study because R-CHOP therapy alone is not considered as standard for these diseases. We calculated the relative dose intensity (RDI), dividing the actually used doses of cyclophosphamide and doxorubicin by the interval between each course compared with the standard doses (750 mg/m² cyclophosphamide and 50 mg/m² doxorubicin every 21 days).

Results: During the study period, data were collected from 100 patients (56 males and 44 females) with a median age of 74 (65-86) years. Sixty patients had advanced stages, 40 patients had a score of at least one in the Charlson comorbidity index (Charlson ME, et al. J Chronic Dis. 1987;40:373-83), 18 patients had a poor performance status (Eastern Cooperative Oncology Group performance status: ≥2), and 14 patients were older than 79 years. The overall response rate was 93%, and the complete response (CR) rate was 81%. Three-year overall survival (3-yr OS) was 78%. In comparison with the international prognostic index (IPI), 3-yr OS was 100% (IPI: low, n=26), 94% (IPI: low-intermediate, n=17), 71% (IPI: high-intermediate, n=24), and 58% (IPI: high, n=33). Hematologically adverse events were generally tolerable. No patient experienced a grade 4 hemoglobin decrease, and only four patients experienced a grade 4 platelet decrease. Although 55 patients received granulocyte colony-stimulating factor, a grade 4 leukocyte decrease was common (n=38) and febrile neutropenia (FN) was often seen (n=21). Patients who experienced FN had a significantly shorter OS (p=0.04). With a median follow up of 44.4 months, 20 patients experienced disease progression and 15 patients died after progression. Five patients remained in CR but died of other types of cancer. The other seven patients died of other causes. The median RDI was 0.81 in patients aged 65-79 years and 0.58 in patients older than 79 years. These doses were very similar to the originally intended doses of 5/6 (0.83) for younger patients and 7/12 (0.58) for older patients. The older group tended to show shorter OS (3-yr OS: 64%). However, recurrence rates of the two groups were very similar.

Conclusions: This study demonstrates that rituximab plus 5/6 or 7/12 doses of CHOP therapy are effective and tolerable for elderly patients aged 65-79 years and those older than 79 years, respectively. It is noteworthy that the prognosis of patients with an IPI score of ≤2 was very satisfactory. Based on these results, the dose intensity does not have to be increased for these low risk groups. It is possible that increasing the dose intensity in high risk (IPI score: ≥3) patients improves the outcome. However, high risk patients tend to have much tumor burden and a poor performance status. In this group, higher dose chemotherapy will also increase the risk of developing FN and might be associated with inferior OS. Treatment of frail elderly patients with high-risk DLBCL is extremely challenging, and we need to gain further experience.