Introduction The use of PBSC transplantation (PBSCT) in allogeneic transplantation is continuing to increase [1]. Initial studies [2–5] showed improved engraftment kinetics when com- pared with BMT and this has now been confirmed by several other reports [6–9]. In addition, there is evidence to suggest that the incidence of acute GvHD is not increased follow- ing PBSCT, despite the infusion of much greater numbers of T cells [7, 9–12]. However several non-randomized comp- arisons of recipients of PBSCT and BMT have suggested that there may be an increased incidence of chronic GvHD following unmanipulated allogeneic PBSCT [13–16]. This is associated with a concern that there may be a concomitant increase in morbidity and mortality associated with use of PBSC for allogeneic transplantation. In contrast, there is evidence to suggest from a recent IBMTR/EBMT analysis that overall survival may be improved in patients with advanced leukemia following allogeneic PBSCT because of a reduction in transplant- related mortality [6]. Evidence suggests that the Cytotherapy (2000) Vol. 2, No. 6, 423–428 423 © 2000 ISHAGE An analysis of the effect of chronic GvHD on relapse and survival following allogeneic PBSC transplantation G Miflin 1 , NH Russell 1 , I Franklin 2 , G Cook 2 , DW Milligan 3 , RM Hutchinson 4 , MN Potter 5 , GJ Morgan 6 , A Pagliuca 7 , J Marsh 8 and A Bell 9 Departments of Haematology, 1 Nottingham City Hospital, Nottingham; 2 Glasgow Royal Infirmary, Glasgow; 3 Birmingham Heartlands Hospital, Birmingham; 4 Leicester Royal Infirmary, Leicester; 5 Bristol Children’s Hospital, Bristol; 6 Leeds General Infirmary, Leeds; 7 Kings’ College Hospital, London; 8 St George’s Hospital, London; 9 Poole Hospital, Poole, Dorset, UK Correspondence to : Professor NH Russell, Department of Haematology, Nottingham City Hospital, Hucknall Road, Nottingham NG5 1PB, UK. Background PBSC are increasingly being used as the source of stem cells in allo- geneic transplantation. An increased incidence of chronic GvHD has been suggested following unmanipulated allogeneic PBSC transplanta- tion (PBSCT), however, how this affects overall survival is not yet clear. Our aim was to study the impact of chronic GvHD on survival and relapse following allogeneic PBSCT. Methods We have analyzed data from 73 patients undergoing HLA-matched allogeneic PBSCT. GvHD prophylaxis was with CYA and MTX in 97% of patients. We have studied the incidence of chronic GvHD and its affect on relapse and survival in these patients. All patients were at least 100 days post-transplant at the time of analysis. Results Seventy-three patients were evaluable for analysis of chronic GvHD. The overall incidence of chronic GvHD was 55% (limited in 18% and extensive in 37%). Overall median survival was 991 days, with a 4 year survival rate of 48%. Twelve patients relapsed. Patients with chronic GvHD had a significantly lower incidence of disease relapse (p =0.005) with a relapse probability of 8% at 3 years, compared with 40% in patients with no chronic GvHD. In addition, the extent of chronic GvHD had a marked effect on survival, patients with limited chronic GvHD had a 4 year survival rate of 83%, compared with 45% in patients with extensive chronic GvHD and 38% in patients with no chronic GvHD. This difference was primarily due to the low incidence of relapse and low mortality seen in patients with limited chronic GvHD. Discussion The presence and extent of chronic GvHD is an important predictor of outcome following allogeneic PBSCT, in that patients who developed either limited or extensive chronic GvHD had a low risk of disease relapse. Keywords allogeneic peripheral blood stem cell transplantation, chronic graft- versus-host disease, survival.