title: Quantifying Benefit of Autologous Transplantation for Relapsed Follicular Lymphoma Patients via Instrumental Variable Analysis.
abstract: The role of autologous stem cell transplantation (ASCT) in patients with relapsed follicular lymphoma (FL) remains controversial because of a lack of proven overall survival (OS) benefit versus nontransplant strategies. We conducted a comparative effectiveness research study involving 3 tertiary Canadian cancer centers to determine whether the ASCT-based approach used at 1 center improved OS relative to non-ASCT approaches used at the other centers. Of 1082 consecutive patients aged 18 to 60 years and diagnosed with FL from 2001 to 2010, the study population included 355 patients who experienced relapse from chemotherapy (center A = 96, center B = 84, center C = 175). Data were analyzed according to the instrumental variable of treatment center to control for confounding factors. The frequency of using ASCT at first or second relapse was significantly different between the centers (A = 58%, B = 7%, C = 5%, P < .001). With a median follow-up of 69.1 months, the actuarial 5-year OS rates after first chemotherapy relapse were 89%, 60%, and 60% for centers A, B, and C respectively (log rank P < .0001). Based on instrumental variable analysis, the use of ASCT at relapse 1 or 2 significantly decreased the risk of death from first relapse (HR .127, P = .004) and from initial diagnosis (HR .116, P = .004). In conclusion, for FL patients who relapse after chemotherapy, these results strongly support more frequent use of ASCT at first or second relapse.
authors.affiliation: Departments of Oncology and Medicine, University of Calgary and Tom Baker Cancer Centre, Calgary, Alberta, Canada.
authors.forename: Danielle H
authors.initials: DH
authors.lastname: Oh
authors.affiliation: Departments of Oncology and Community Health Sciences, University of Calgary, Tom Baker Cancer Centre, Calgary, Alberta, Canada.
authors.forename: Haocheng
authors.initials: H
authors.lastname: Li
authors.affiliation: Biostatistician, Research Facilitation, Alberta Health Services, Calgary, Alberta, Canada.
authors.forename: Qiuli
authors.initials: Q
authors.lastname: Duan
authors.affiliation: University of British Columbia and British Columbia Cancer Agency, Centre for Lymphoid Cancer, Vancouver, British Columbia, Canada.
authors.forename: Diego
authors.initials: D
authors.lastname: Villa
authors.affiliation: University of Alberta and Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: Anthea
authors.initials: A
authors.lastname: Peters
authors.affiliation: University of Alberta and Cross Cancer Institute, Edmonton, Alberta, Canada.
authors.forename: Neil
authors.initials: N
authors.lastname: Chua
authors.affiliation: Departments of Oncology and Medicine, University of Calgary and Tom Baker Cancer Centre, Calgary, Alberta, Canada.
authors.forename: Carolyn J
authors.initials: CJ
authors.lastname: Owen
authors.affiliation: University of British Columbia and British Columbia Cancer Agency, Centre for Lymphoid Cancer, Vancouver, British Columbia, Canada.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Connors
authors.affiliation: Departments of Oncology and Medicine, University of Calgary and Tom Baker Cancer Centre, Calgary, Alberta, Canada. Electronic address: douglas.stewart@albertahealthservices.ca.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Stewart
mesh_terms: D000293:Adolescent; D000328:Adult; D000416:Alberta; D064592:Autografts; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D018380:Hematopoietic Stem Cell Transplantation / Q000295:instrumentation* / Q000379:methods*; D006801:Humans; D008224:Lymphoma, Follicular / Q000401:mortality* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D015996:Survival Rate
keywords: Autologous hematopoietic stem cell transplant; Comparative effectiveness analysis; Follicular lymphoma; Instrumental variable analysis