Thesis (M.A.) PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / High dose chemotherapy followed by autologous stem cell transplantation (ASCT) remains the standard of care for patients with relapsed or refractory (R/R) diffuse large B cell lymphoma (DLBCL) who are chemosensitive to salvage therapy. There is now evidence that the achievement of complete remission by PET scan (PET-CR) after salvage therapy is a favorable determinant of ASCT outcome, implying that PET response should be part of the prognostic assessment for patients considering ASCT. However, it is unclear whether other prognostic factors are still relevant in patients getting post-salvage PET scanning. Moreover, while ASCT is often also used for patients with R/R transformed indolent lymphoma (TIL), there are no data on whether prognostic factors that are important for DLBCL patients, especially PET response to salvage, are similarly prognostic in this population. We conducted a retrospective study of 143 patients with R/R DLBCL and TIL who were transplanted in the last decade and had a post-salvage PET scan prior to ASCT. We examined prognostic factors in both groups, and constructed a prognostic score for DLBCL patients. For patients with DLBCL, post-salvage PET response was an important prognostic factor. Advanced age and symptomatic relapse were also significantly associated with inferior outcome. A simple score could stratify patients into 3 risk groups with 4-year post-ASCT overall survival of 84%, 59%, and 10%, and 4-year progression-free survival of 67%, 41% and 0% (p<0.0001 for both). However, none of those factors (including PET response to salvage) could be demonstrated for TIL, likely because of the limited sample size. Our novel prognostic score for DLBCL patients undergoing ASCT may be useful for prognostication, for stratification in clinical trials, and to motivate the design of new strategies for patients in the highrisk group, who may not derive benefit from standard ASCT. Those factors, however, do not apply to patients with TIL, which has important implications for their treatment and inclusion in ASCT clinical trials with larger sample sizes. / 2031-01-01