Update on Stem Cell Transplants
Ottawa, June 2012
One my hospital’s hematologists gave this to our local support group. These notes have not
been validated, so the usual caveats apply.
After a brief history, starting with the post-Hiroshima linkage between radiation and
cancers, he noted the early transplant results in the 60s were poor, largely due to lack of
knowledge of blood typing and thus bad matches. In the 70s, the major development was
the establishment of the international transplant registry, which collected and shared data,
providing a knowledge base to inform treatment. There were relatively few transplant
centres in the 1980s, but by then studies had shown that the principle of transplanting
bone marrow was sound.
Some of the major developments that started to improve success rates were more accurate
blood typing (HLA), better antibiotics to manage complications.
The previous distinction between auto SCTs, used when the underlying problem was not
bone marrow related and drugs such as Neupogen made this viable, and allo, used when it
is a bone marrow issue, still largely applies but, as in my case, is not iron-clad.
Over the past 30 years, the main barriers to success have not changed:
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Original disease-related death (i.e., dying from the original cancer, about 50%)
Side effects of intensive chemo and radiation, ranging from short to longer-term
(about 20%)
Side effects from new immune system, including GvHD and infection (risk is
dramatically lower after one year)
However, during this time, improvements are significant:
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Accurate blood typing given improved technology: if match, it really is a match
Better handling of GvHD given huge advances in drugs (e.g., immunosuppressants)
Development of peripheral blood cell collection, which provides for a quicker
recovery than bone marrow cells (quicker recovery means lower risk of infections)
and a more active system. The price to pay (there always is a trade-off is greater risk
of GvHD). In general, for more aggressive cancers, the quicker recovery and increased
new immunity is preferred; for less aggressive cancers, bone marrow cells may be
used to reduce the risk of GvHD.
Neupogen, the drug used to stimulate white blood cell production and reduce the
duration of low immunity and vulnerability
New anti-fungal drugs to reduce risks without ‘wrecking’ kidneys
And a number of simple things: Zofran for nausea, CMV (Cytomegalovirus)
monitoring to prevent pneumonia, now replaced by PCR (Polymerase chain
reaction) testing with a shorter time required for Acyclovir (anti-viral drug)
Some other changes flagged:
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Pendulum keeps shifting between harsh and less harsh conditioning regimes, and is
currently swinging back to the full myeloblative regime that I had. High radiation, in
particular, keeps one’s old immune system at bay for about 6 months, enough time
for the new system to strengthen.
In general, the bias is to do transplants sooner rather than later, as the timing affects
the success rate. However, complementary treatments and drugs can postpone the
need for transplant
Former hard rules about age limits for transplants have shifted to looking at
individual patient health (physiological age, not chronological – is the patient strong
enough?), combined with an aging population, and higher treatment expectations
Greater understanding of the spectrum and variants of cancers, and increased
complexity of treatment
Overall risk of death from treatment has decreased from 40 to 20 percent from 1995-2004,
due to better patient selection, better drugs and better supporting care and managing
complications. Overall survival rates have increased 12 to 15 percent over this period,
incremental but in the right direction.
And some additional ongoing challenges, in addition to ongoing improvements:
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Providing care for ‘survivors’ as longer-term effects of treatment and transplant
emerge
Improved cost and other efficiencies in providing care
Analysis of clinical trials to adjust treatment and transplant approaches