On Friday we traveled to Durham to visit Duke Medical Center and meet with part of the team there who will likely be handling Zoe’s Stem Cell Transplant. Overall it was a great visit, very positive and we gained a good deal of insight into the process.
Because of the wide-ranging nature of what we discussed, I’d like to break it up some and cover what’s going on with more than one post.
First, the SCT itself and what we now know we can expect.
Let’s talk a little about statistics. Briefly. Not my favorite subject either, believe me.
I have previously discussed the mortality rates for children going through a Stem Cell Transplant (SCT) based on both the research I’ve done and on the numbers I was given from Duke originally. As expected though, context helps put those numbers in perspective, and the outlook is not nearly as poor as we might have feared.
The problem is sample size — in this case, the amount of children who have had the procedure at Duke. The sample size for HLH is very small, and as such even one poor outcome skews the result vastly. Only 8-20 children are estimated to develop HLH per year, making it hard to get a clear picture.
I could say that 50% of the cars on my block are blue, for example, and that might be a true statement. But if there are only 2 cars on my block (2 in the sample), does that 50% begin to seem like a misleading number? In some cases, it might.
In the case of the SCT procedures done at Duke on patients with HLH, the number is 14. Of those, 5 did not survive long term. What we now know however is that there are a lot of factors that make that number less frightening.
- All of the patients who did not survive long-term had their procedure prior to the year 2000
- Since 2000, many things have changed with regard to medicines and procedures, reducing the risks
- All of the HLH patients at Duke since 2000 have survived
- All of the patients who did not survive have factors that distinguish their cases from that of Zoe or perhaps other more recent HLH babies.
Of the patients that did not survive:
- One died in 1991, prior to both the HLH-94 and HLH-2004 protocols — his treatment was simply not as effective because not as much was understood about the disease, and he lost a long fight
- One died of a fungal infection — since the time of that patient’s death, a medication called Vfend has become a standard part of treatment, and would likely have saved that child had they had that medication at the time. Zoe takes Vfend 2x a day.
- Two died due to viral infections they had at the time of their transplant — that means they went into the procedure in poor health, likely because they had no other choice
My notes are incomplete on the 5th, but the overall point of the discussion at the time was that there were clear reasons that each child did not make it. It was not simply a matter of Russian roulette — these children were not at their best or were lacking medicines that, had they been born today, could have saved their lives.
Gives you new respect for medical research.
With this information in mind, the 70% survival rate begins to seem like a problematic number. The real number is likely much higher. The risks are still very much present, but we are no longer going into this feeling like our chances of losing Zoe are so high as to be soul crushing.
The two risks most on the mind of Dr. P are Graft Versus Host Disease and infection (bacterial, viral, etc). The risk of GVH is mitigated somewhat by the type of material to be used in Zoe’s transplant, cord blood. Cord blood procedures are understood to have a lower risk of Acute GVH vs. donated marrow procedures. The risk is there, but lessened.
The risk I had most been fearing was that of VOD, a specific complication of the transplant procedure. I have been living in fear of it due to the fact that several of the HLH children whose stories are public on the web did not survive it. I was greatly relieved to hear that Duke has access to a medication that takes much of the danger of that off the table. It is not FDA approved, however it is available to some hospitals on a “compassionate” basis. Duke is among the hospitals testing it, and they hope to see its FDA approval so that it will be in use more widely. Regardless, Dr. P felt confident that VOD would not be as risky for Zoe as it has for other children in the past.
So. 99% of patients survive the conditioning regimen. 90-95% of patients achieve a graft of the transplanted cells. Slowly, slowly, our fears are being replaced by facts.
Zoe will begin her procedure in the best health we can hope for while still fighting the disease — no known infections, good overall health and, by the time of the procedure, good counts (we hope). Risk of bacterial infection greatly reduced. Risk of GVH reduced. Risk of VOD greatly reduced.
Reasons for hope indeed.
There are a lot of questions we’ve been asking ourselves.
What can we do to help Zoe survive this?
Is she getting the right treatment?
Is Duke the best possible hospital for her transplant?
We want her to have every chance, so we regularly beat ourselves up trying to be sure we’re not making mistakes. The answers are hard to come by though.
What we know is this: we are doing everything we can for Zoe within our power. We are researching everything as best we can and challenging Zoe’s doctors (nicely! :)) when we aren’t sure of something, to be sure they are and be sure we understand why they are.
And, we now know that Duke is as good if not the best at pediatric transplants in the US. They do more unrelated (cord blood, marrow) pediatric BMT and SCT procedures than anyone in the country from what I understand. We feel we are in the best hands for the procedure that Zoe is going to have.