Context: Recently, great efforts have been made to understand the pathogenesis of bone loss following allogeneic stem cell transplant (allo-SCT) and possible treatments.

Evidence Acquisition: A literature search of the MEDLINE database was performed to find articles in English using the search terms "allogeneic stem cell transplant" or "bone marrow transplant", in combination with "bone loss," "osteoporosis treatment," "osteoblast," "cytokines" or "osteoprotegerin." Reference lists from the articles retrieved were also evaluated for relevant information.

Evidence Synthesis: Bone mineral density (BMD) at the lumbar spine, but not at the femur, can improve or even recover several years after SCT. Multiple risk factors for post-transplant bone loss have been recently identified: abnormalities in the immune system function and their treatments; reduced production of growth factors, osteoclast activation by increased cytokine release, and decreased number and function of osteoblast precursors within the stromal stem cell compartment. Pamidronate was partially successful in preventing post-transplant bone loss, while both oral and parenteral bisphosphonates had beneficial effects on documented osteoporosis in long-term survivors.

Conclusions: There is clear evidence that transplant-related bone loss is a multifactorial, early and possibly long-lasting disorder. All patients who have already received allo-SCT should be evaluated as to their bone status and treated with appropriate supportive measures and specific treatments as soon as abnormalities are detected. Although preventive antiresorptive treatments are only partially effective, they should be started in all patients before or at the time of allo-SCT, regardless of their BMD values, and continued at least for the first year post-transplant.