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Outcome of primary mediastinal large B-cell lymphoma (PMBCL) in the pre- and post-rituximab era: The Stanford University experience.
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: For PMBCL the role of radiation therapy (RT) following rituximab (R)-based regimens is unknown. The purpose of this study was to evaluate the outcome of PMBCL according to treatment-specific eras and identify whether RT after R-based therapy improved outcome. Methods: We retrospectively identified patients (pt) with newly diagnosed PMBCL treated at Stanford over two eras: 1975-2002 (pre-R) and 2003-2009 (post-R). Charts were reviewed for pt characteristics, therapy, and outcomes. Freedom from progression (FFP) and overall survival (OS) were estimated by Kaplan Meier methods and differences in strata were compared with log rank tests. Comparisons of treatment regimens were performed using the Freeman-Halton extension of Fisher’s exact tests. Results: 80 pts were identified; pre-R era (n=54) and post-R era (n=26). Median age 33 years (range 19 to 68), 59% females, stage I-II (n=68), stage III-IV (n=9) and unknown (n=3). Pt characteristics were similar in the two eras. Treatment regimens in the pre-R era consisted of RT alone (n=4) or chemotherapy (CT) with CHOP (n=7), CHOP + RT (n=16), MACOP-B/BACOD (n=4), BACOD/MACOP/VACOP-B + RT (n=17), other (n=6), and post-R consisted of R-CHOP + RT (n=5), R-VACOP-B + RT (n=12), dose adjusted (DA) EPOCH-R (n=9). At a median follow-up of 5.3 years (14.5 years pre-R, 2.9 years post-R), the overall FFP and OS were 88% and 81%, respectively. FFP in the pre- and post-R eras was 81% versus 100% (p=0.0376) and OS 72% versus 100% (p=0.0167), respectively. Pts treated with CT + RT versus R-CT+/-RT had a FFP of 85% versus 100% (p=0.122) and OS 80% versus 100% (p=0.058), respectively. The outcome of pts in the R era treated with or without RT was identical with a 100% FFP and OS. Conclusions: Our data confirm improved outcomes for pts with PMBCL treated in the R era. The addition of RT after R-CT did not further benefit the FFP or OS. Our analysis, though limited by small numbers and short follow-up, confirm emerging data that RT may be avoided with the use of regimens like DA-EPOCH-R. Although these results require confirmation in a randomized prospective trial, the elimination of RT is an important consideration in an entity that predominantly affects young women.