Differential Outcomes of Synchronous and Metachronous Diffuse Large B-Cell Lymphoma Transformed from Follicular Lymphoma

Aim:

Composite histologies of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) may be present synchronously at diagnosis or metachronously at the time of transformation of a formerly diagnosed FL. The aim of this study was to examine their clinico-pathological characteristics and treatment outcomes.

Method:

Patients who were consecutively diagnosed with composite FL/DLBCL (n=120) and FL (n=346) from 2001-2017 at the National Cancer Centre Singapore were retrospectively analyzed. Chi-squared tests and multivariate logistic regression were performed to evaluate clinico-pathological associations between the two cohorts. Survival analysis was performed using the Kaplan-Meier method and the log-rank test.

Results:

Amongst the FL cases, 21 patients (6.1%) with metachronous transformed FL/DLBCL were identified. The median lag time from diagnosis of FL to DLBCL transformation was 47 months (range, 7.8-168). Clinico-pathological features in synchronous and metachronous FL/DLBCL were similar, with both entities demonstrating a male preponderance (67% male and 33% female). Median age at diagnosis was 67 years (range, 41-81) and 60 years (range, 24-90) for metachronous and synchronous FL/DLBCL, respectively. The cell-of-origin by Han's criteria was similar (metachronous: GCB 52%, ABC 43%, unknown 5%; synchronous: GCB 38%, ABC 57%, unknown 5%; p = 0.21), as were the occurrence of C-MYC/BCL2/BCL6 double-hit rearrangements. However, survival from the time of DLBCL development was significantly worse (median, 3 vs 12 years) for metachronous compared to synchronous FL/DLBCL (HR 2.20, 95%CI 0.88-5.49, p = 0.022). Double-hit, advanced stage, and use of non-RCHOP regimens (OR 7.54, 95%CI 2.84-20.1, p = 0.0001) were associated with lack of complete response to chemotherapy. In metachronous FL/DLBCL, the R-CHOP regimen was less commonly used (77% vs 56%, p = 0.049). Correspondingly, complete response to chemotherapy was less likely in metachronous cases (38% vs 63%, p = 0.037).

Conclusion:

Metachronous and synchronous FL/DLBCL share similar clinico-pathological characteristics.

A preceding diagnosis of FL however, predicts for significantly worse survival outcomes and suboptimal responses to chemotherapy.