Autologous hematopoetic stem cell transplantation (aHSCT) after high dose chemotherapy is a standard treatment for multiple myeloma (MM) patients. The successful aHSCT depends on collection of sufficient numbers of hematopoietic progenitor stem cells and sustained engraftment following infusion. The aim of the present study is to determine the the impact of bone marrow fibrosis (BMF) on the clinical outcomes of MM patients who underwent aHSCT.

Retrospectively, bone marrow trephine biopsy analyzed in 73 MM patients who were treated with hematopoietic stem cell transplantation (aHSCT) following bortezomib based induction regimen. The BM biopsy samples of all patients were re-evaluated by a single pathologists The patients divided into 4 groups according to fibrosis degree and the correlations in initial characteristic features, therapeutic response, survival, mobilization and engraftment outcomes were reviewed between the groups.

Comparative analyses revealed that the median apheresis number was found statistically different according to groups (p=0.04). No significance was detected between the fibrozis grade and the number of peripheral blood CD34+ cell collection results and recovery time of neutrophils and platelets. Overall survival and progression free survival were found similar in groups, however relapse of disease was statistically different in patients with fibrosis (p=0.01).

After induction treatment, a regression was observed in fibrosis grade of patients who had fibrosis at the time of diagnosis. Therefore we suggest to evaluate fibrosis status in all MM patients during each histopathological examination. Difficulties may be experienced during stem cell collection in transplant eligible MM patients with fibrosis at diagnosis. Therefore, we recommend that clinicians should be more careful in these patients during the induction treatment and stem cell mobilization.