Unrelated-donor marrow transplants: the experience of the National Marrow Donor Program.

As of January 1996, more than 4,000 marrow transplants have been performed using unrelated donors provided by the NMDP. With more than 1.9 million donors listed in the registry, over 70% of patients now find an HLA-A, -B, -DR phenotypic match at the initial search. The success rate is dramatically lower for patients in racial minorities. For instance, African-Americans find donors only 34% of the time on the initial search. Analysis of the first 462 transplants, showed disease-free survival rates at 2 years to be approximately 40% in low-risk patients, and 20% in high-risk patients. A more recent analysis in single centers shows an increase in the probabilities to 60-70%. This increase in success is likely related to a number of factors, including the ability to control complications, such as GVHD, plus an increase in accuracy of HLA typing primarily based on DNA-based methodology.