Good morning.
I wish to thank the committee for inviting me to speak to this important issue in the role of a transplant physician.
When I am facing a patient who has reached the point of requiring a stem cell transplant, and if no family donor has been found, I am asked, with tremendous hope but also with a high level of anxiety, “Doctor, what is my chance of finding a donor in the registry?” How much more rewarding would our task be and how much more would a patient appreciate it if the answer would always be, “I can reassure you, there is a high likelihood that we will be able to find a donor for you in the right frame of time.”
Unfortunately, we have not reached this stage. We hope to get there soon.
Hematopoietic stem cell transplantation, known also as a blood and marrow transplantation, is a curity procedure for life-threatening blood cancers and other bone marrow disorders. The single most important donor factor in determining transplant outcomes is a degree of matching known as HLA matching, or, in other words, the immune equivalent of the fingerprint match between the patient and the donor.
There is approximately a 25% chance that two siblings inherit the same immune fingerprints, which translates to only a probability of 30% that someone will have a suitable sibling match in a family, mainly due to the small size of Canadian families. Thus, donation of hematopoietic stem cells from an unrelated donor has become the only available option for 70% of patients in need of unrelated stem cell transplants.
The success of securing an unrelated stem cell donor for a particular patient depends on many factors, but the very important one is the ethnic background of the patient. The smaller the ethnic group the patient belongs to, the less likely such a patient will find a suitable donor in any registry, including the Canadian registry, as their representation in the donor group is significantly lower.
Stem cell transplantation is often the last hope for a curative option for these patients. Their disease is at the point at which no better alternative exists. The waiting period for a search to complete, the hope that they will be the lucky one to find a suitable donor, and the potential curative nature of the procedure hangs heavy in a patient's mind.
The ability to tell a patient that we have found a donor is always emotionally charged and rewarding. It is among the best news the patient can get when transplantation is needed. The reverse is heart-wrenching, for the patient and their family, and it leaves us, their physicians, with a sense that we have not done enough for their well-being.
In order to find the best available donor, individual donor registries collaborate internationally. However, despite the number of adult donors already registered, many patients in need of a stem cell transplant still cannot find an acceptable donor because they have a rare tissue type.
In 2008, there were 10,400 adult stem cell donations and 3,500 cord products were used. Through these global efforts over the years, a total of 100,000 patients have received stem cell transplants worldwide.
Despite these heartening figures, many patients remain unable to find a suitable stem cell donor within their own country's registry. Thus, the percentage of products crossing international borders has increased over time. In 1997, 30% of products crossed an international border, and this grew to 44% in 2008.
Currently, as mentioned before, there are over 14.9 million registered unrelated donors and 450,000 blood unit cord banked worldwide. However, the number of donors in Canada is smaller. In Canada, the OneMatch stem cell and marrow network, under the auspices of Canadian Blood Services, is responsible for finding and matching volunteer donors for patients who require stem cell transplants. OneMatch maintains a detailed database of tissue typing results of all prospective Canadian donors. The ethnic composition of OneMatch, including Héma-Québec, is 81% Caucasian, 15% ethnically diverse, including a total of 266,000 donors who comprise about 1% of the Canadian population.
The age of recruited donors is also becoming important. On the basis of published data describing that the use of younger donors may lower the incidence of complications from transplantation and improve survival, some registries have recently started to focus recruitment on younger donors. There is a particular need to increase younger registrants and those from ethnically diverse backgrounds.
Concomitantly, an increase in the availability of cord blood units will act synergistically in enhancing the ability to find a suitable donor for patients. Cord blood units are more likely than any other source of stem cells to expand rapidly, because of cord blood's wide availability and ease of collection, with no major burden to the donors.
The specific benefit of cord blood units is that a lesser degree of matching is acceptable and leads to clinical outcomes similar to those in which unrelated donors are used. These units are fast becoming a significant stem cell source for patients who cannot find a suitable donor within the unrelated donors registry.
The process of stem cell donation has changed significantly over time, over the last year particularly. While bone marrow is a rich source of stem cells, the ability to collect stem cells from peripheral blood, also known as peripheral blood stem cells, and from umbilical cord blood has changed the way we obtain stem cells today.
Because the donation of peripheral blood stem cells does not require a surgical procedure, is efficient, and is more acceptable to donors, it has become the predominant form of stem cell collection worldwide. Unlike the donation of organs such as kidneys, the donation of peripheral stem cells is much less complex, both technically and psychologically. The stem cells are a renewable source, and donating them is only slightly more complicated than donating blood. However, the benefit is similar to donating any other important organ or tissue: the benefit of saving a life.
The altruistic nature of people willing to donate stem cells has to be highly appreciated, and their safety has to be properly ensured. Donor safety must be a priority, and they should not be asked to take unacceptable risks. Any medical and psychological condition that increases the risk to a donor has to be thoroughly investigated, resulting in either deferral or approval for donation.
I will make some concluding remarks.
In 2008, among 462 transplants done in Canada using a stem cell donor, 179 received a stem cell transplant from an unrelated donor, including umbilical cord blood.
Unfortunately, I do not have the number of unsuccessful searches and as such the number of patients who could not find a stem cell donor and could not be rescued by this procedure. The ability of every Canadian patient who requires a stem cell transplant to find a suitable donor is an important goal that we should strive to achieve. The ability to do so resides in having all the stakeholders work together towards this common goal.
Some of the measures to achieve this important goal should include: a focus on the increasing enrolment of ethnic minorities and mixed minorities; a focus on the increased enrolment of younger donors, aged 18 to 35, as the youth of their stem cells can lead to better transplant outcomes, as published; the establishment of a national cord blood bank in Canada, ethnically diverse, which would be a complementary and long-awaited stem cell source for many patients who cannot find an unrelated donor match; increased funding for research in the area of mismatched donor transplantation, to establish whether manipulation, a graft, and/or the recipient's immune system can lead to improvement in clinical outcomes; continuing the present efforts and adopting new ways to increase awareness among the Canadian public about the importance of becoming a stem cell donor; and perhaps increasing funding to allow for the thorough and accurate reporting of the outcomes of stem cell transplants to the Canadian Blood and Marrow Transplant Group, the only group that collects this clinical data, which in turn might lead to improvements in transplantation outcomes.
As transplant physicians, we would like to be able to offer to any patient in need of a stem cell transplant a suitable donor match that would improve his or her chances of survival and ultimately lead to a long, happy, and productive life. I hope we will be able to accomplish this through our present meeting and other future endeavours.
Thank you.