Allogeneic stem cell transplantation in follicular lymphoma: recent progress and controversy.

Allogeneic stem cell transplantation (allo HCT) is a curative treatment for follicular lymphoma, but is hampered by a relatively high treatment-related mortality and by difficulties in identifying high-risk groups for whom transplant is warranted. Results with myeloablative conditioning have improved, but the field has shifted largely to reduced-intensity conditioning and non-myeloablative transplantation, though morbidity and mortality are also substantial. Some groups have investigated T cell-depleted transplantation, which results in a low rate of chronic graft-versus-host disease (GVHD) and, in most studies, excellent rates of disease control. Overall, outcome after alloHCT for follicular lymphoma correlates more with disease status, with performance status and with comorbidities than with any particular conditioning regimen used. For patients with chemotherapy-sensitive disease, the treatment-related mortality has stabilized in the 15% to 20% range and, depending on the method of GVHD prophylaxis and the donor type, there is an additional 20% to 60% incidence of chronic GVHD. For patients with chemotherapy-refractory disease, both treatment-related mortality and recurrence rates are much higher, but their prognosis is dismal with other treatments and some may be cured, particularly with myeloablative transplants. Ongoing studies focus on improving conditioning regimens, on prevention of disease recurrence and on decreasing chronic GVHD.