Melomed Articles


6 August 2019 - Dr. Shahroch Narhwar

August: Bone Marrow, Stem Cells Donation and Leukaemia Awareness Month


Every year, more than one hundred thousand South Africans are diagnosed with cancer (globally 14 million people) of which 60% survive. Globally cancer kills more people than TB, AIDS and Malaria combined.
Although leukaemia2, lymphoma3 and myeloma4 are relatively uncommon cancers and feature last in the top ten of all cancer deaths in South Africa (4% of all cancer deaths) they are potentially curable with chemo5-and radiotherapy6 even when wide-spread at diagnosis, which is very unusual for other types of cancers. 
 

Leukaemia, myeloma and lymphoma survival rates have more than doubled over the past thirty years in stark contrast with dismal survivals of oesophagus, stomach, lung, pancreas and brain cancer. 
 
Leukaemia, myeloma and lymphoma are also frequently treated with high dose chemo-and radiotherapy followed by blood stem cell transplants, especially for high risk of relapse7.
Allogeneic8 stem cell transplants9 are mostly performed for acute10 leukaemias and should ideally only be done if the patient is in remission11 after initial treatment with chemotherapy.
For more than 20 years, blood rather than bone marrow is most often used in which the stem cells are being harvested by an apheresis machine (cell separator) which separates these stem cells from the blood (returned to the body) after stimulating the donor's bone marrow with subcutaneous12 injections of white cell growth factor for 4-5 days, infused thereafter to the patient.
 
Full sibling13 donors have a 1:4 chance to be a full tissue match with patient. They are still the best donors for stem cell transplants compared with voluntary unrelated or related haplo-identical14 donors 
To find an unrelated donor is difficult (less than 1:100.000 chance per donor) for black and mixed-race patients (compared with 1:10.000 chance for whites) because of complex ethnicity15 causing a wide variety in tissue types which contrasts with white donors who are genetically more identical and therefor have a much higher chance of tissue matching a white patient fully. Therefore, there is a 97% chance to find a (white) unrelated donor for a white patient baring in mind that funds are available since this is a very costly process (roughly R500.000 per transplant) and since more than 80% of all South Africans do not have medical insurance, difficult to finance.
 
For over a decade, haematologists have developed the haplo-identical transplant for half-matched family donors which makes it possible to transplant almost all patients in need of a bone marrow/ blood stem cell transplant since almost everyone has got either a living parent, sibling or child.
These stem cell transplants are more difficult to perform because of higher rejection rate (compared with full sibling transplants) but are much cheaper and easier to access than unrelated stem cell donor transplants and therefor accessible also to the less privileged patients.
The success of a stem cell transplant is measured initially in terms of engraftment16 and recovery of both neutrophils17 and platelets18 which should exceed 500 neutrophils per ml and 20000 platelets per ml of blood.

 
Glossary:
1. Doctor who cares for and treats patients with diseases of the blood and blood-forming organ (blood, bone marrow, lymph tissues)
2. Blood and bone marrow cancer usually arising from white blood cells.
3. Lymph (gland) cancer
4. Bone marrow cancer arising from plasma cells (type of white blood cell that produce antibodies)
5. Chemicals that kill (cancer) cells
6. Invisible, high energy waves that kill (cancer) cells
7. Disease coming back after treatment
8. Tissue from another person
9. Transferring bone marrow cells from one person to another
10. Rapidly growing
11. Disease free after treatment
12. Under the skin
13. Related brother or sister from same parents
14. Half-matched (50% identical)
15. Belonging to a social group that has a common national or cultural tradition
16. Blood-forming cells you received on transplant day start to grow and make healthy blood cells.
17. Type of white blood cells that are the first to fight infections
18. Cell fragments that start the process to stop bleeding.

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