Background: Primary mediastinal B-cell lymphoma (PMBL) has been treated with different chemotherapy regimens. We reviewed medical records and histopathology to determine predictive factors and outcomes for patients (pts) with PMBL seen at the MD Anderson Cancer Center (MDACC) between 1995 and 2013. Methods: Baseline characteristics complete (CR) and partial (PR) response to initial therapy, and status of disease and survival over time were collected. Event-free survival (EFS) was based on dates of relapse, progression, or death. Radiotherapy data will be presented separately. Results: 274 pts with PMBL were identified, making this the largest single-center retrospective report of PMBL. Median age was 40 years (range, 17-86), and 149 pts (54%) were female. For patients treated with R, the CR rates were higher, and EFS and overall survival (OS) were improved for all pts at the median follow-up (MFU) of 38 months (mo), and for CHOP-treated pts at MFU of 37 mo (Table). As R is now standard with initial therapy, we analyzed results for the 3 main R-containing therapies (Table). By univariate log-rank analysis, therapy choice affected the CR rate, and EFS at MFU of 39 mo. R-HCVAD had superior EFS vs. R-CHOP (p=0.015), even though low-stage pts were more common for R-CHOP. For pts given the 3 main R-containing therapies, higher stage (III/IV vs. I/II) was an adverse univariate predictor for EFS (p=0.036) and OS (p=0.04), and B symptoms were adverse for OS (p = 0.026). Multivariate Cox analysis including stage, B symptoms, and therapy (CHOP vs. EPOCH/HCVAD) found only B symptoms to be predictive of shorter OS (p = 0.032), and only treatment to be predictive of shorter EFS (p=0.029). Conclusions: Response rates and survival outcomes are improved for pts with PMBL by R and its use with intensified therapy (R-HCVAD or R-EPOCH). Longer follow-up is needed to compare R-HCVAD and R-EPOCH.

Abbreviation: NS, not significant.