The calculations leading to that conclusion are as follows:

Data provided by international transplant registries (IBMTR/ABMTR) (1) indicate that about 11,250 allogeneic hematopoietic cell transplants using HLA-matched related donors are performed annually throughout the world.

It is generally estimated that about 70% of patients in need of a transplant do not have an HLA-matched related donor. Accordingly, the ratio of patients without a related donor to patients with a related donor = 70:30 or 2.3:1.

Therefore, if there are 11,250 patients who have an indication for a transplant and who have an HLA-matched related donor, there must be about 26,000 patients annually (11,250 x 2.3 = 25,875) who have an indication for a transplant but who do not have a related donor.

In contrast, the IBMTR data indicate that only about 3,750 allogeneic hematopoietic cell transplants using matched unrelated donors are done annually.

One can conclude, therefore, that about 22,000 patients per year (25,876 - 3750 = 22,126) have an indication for a transplant but do not receive one.

Kollman et al (2) point out that the probability of finding an available donor from the NMDP registry is 27% for blacks, 45% for Asian/Pacific Islanders, 75% for whites and 48% for Hispanics. Thus, at least part of the reason patients who have an indication for a transplant but are not transplanted is due to the fact that an appropriate donor stem cell product is not found among family members or registries of adult donors. (Other barriers to unrelated donor stem cell transplantation are described by Kollman et al (3) (see Annotated Bibliography, VI. Availability and time required to obtain cord blood versus bone marrow, citation #9)

Can umbilical cord bloods satisfy that need?

(A) Is it feasible to find an adequately matched cord blood unit or units for most patients in need of a transplant?

Barker et al (see Annotated Bibliography, III. Multi-Cord Transplants, citation #1) point out they were able to find two suitable cord blood units for 23 of 26 (88%) patients in a study of multi-cord blood transplantation and that the other three patients (12%) received a single unit graft (4).

For further information about the availability of cord blood units see: Annotated Bibliography, VI. Availability and time required to obtain cord blood versus bone marrow.

(B) Do the outcome results justify the use of cord blood units for transplantation of adults?

The publication by Barker et al (see Annotated Bibliography, III. Multi-cord transplants, citation #1) of 23 adult and adolescent patients with high-risk hematologic malignancies indicated that all evaluable patients (n = 21) engrafted at a median of 23 days and that the incidence of severe aGVHD was low despite HLA disparity. The one year disease-free survival for patients transplanted with acute leukemia in remission or with CML (n = 15) was 72%. Double unit cord blood transplantation extends access to transplant to many patients who were previously disqualified on the basis of the available cell dose in a single unit. Note that, if the patients required a transplant within 3 months of referral, cord bloods were given priority over alternative sources of stem cells, i.e., bone marrow or peripheral blood.

For further data about transplantation of adults with cord blood units, see Annotated Bibliography, II. Transplantation of Adults.

Conclusion:
One can conclude that no patient who is in need of a transplant should be denied that procedure because of a lack of a donor unless a search for cord blood units has been carried out. Further, an appropriate cord blood unit or units can be identified for a large percentage of patients in need of a transplant.

Utilizing this approach should satisfy the unmet need.
Why, then, are there more than 20,000 patients per year who have an indication for a transplant but who are not transplanted? One can propose that one of the reasons is reluctance on the part of transplant physicians to use cord bloods.

Please send any comments to: medical.network@cordbloodforum.org