Risk of progressing from smoldering to active myeloma

A recent exchange with a blog reader/myeloma patient list member made me rush to re-read and re-post about a 2007 Mayo Clinic study titled “Clinical Course and Prognosis of Smoldering (Asymptomatic) Multiple Myeloma” (the full study is now available: http://tinyurl.com/c9f8lb).

 

It is based on a review of Mayo Clinic smoldering myeloma patients whose risk of progression to active myeloma was calculated at 10% per year for the first 5 years, 3% for the next 5 years and 1% for the last 10 years (“last”? Hmmm…). But read this: the cumulative probability of progression was 73% at 15 years.

 

I knew about this study, I even posted about it after it was published, but, I confess!, back then, for some inexplicable reason, I completely missed what I now consider to be one of the main points: the cumulation business. Okay, I am hardly a math genius…never was, never will be. But I must also have been in denial at the time, because the study spells it out…very clearly…as we will see.

 

First, another admission: I probably would have paid more attention to this study if it had focused on my own age group, give or take a few years, in a similar state of, uhm, good health. I have always been very very (very!) wary of statistical studies…there is so much missing information, blablabla. I find these studies interesting, but that’s where it ends.

 

Anyway, point is, what I remembered about the study’s percentages was totally wrong. I thought that after 5 years spent in a smoldering state, the risk of progression to active myeloma went down to 3%. Well, sure, technically that is what happens, according to the Mayo study, but it’s not that simple.

 

It’s not as though you begin each smoldering year from scratch. With every year that passes, in fact, you have to add the risk percentage that you accumulated in previous years. My blog reader set me straight on this point: the progression risk is cumulative. That means that after, say, six smoldering years, your risk of progression is as follows: 10 x 5 = 50 + 3 = 53%. Oh boy, there is quite a difference between 53 and 3%!

 

Let’s see, based on this study’s group classification, I would be in group 1. So, now that I am in my fourth smoldering year (as far as I know), my present risk of progression to active myeloma would be about 40%. Not too staggering. But what shocked me for a split second is this: even if my overall risk percentage drops from 10% to 3% next year, my cumulative risk percentage could reach 90% in 2020. 90%??? A question popped into my head as I read that: has anybody gone beyond the 100% threshold? Okay, that’s my goal now…to pass that threshold…!

 

Another thing caught my eye: The median time to progression was 2 years in group 1. Well, I am way past the median point…I have been in group 1 (in fact, a couple of times I even jumped into group 2, a “better” group in terms of progression risk) for 3.5 years, now, so I have beaten the median time, at least.

 

You can read the study on your own and, if you are smoldering, figure out what your risk of progression might be. Or…not. You see, I am not at all sure that I am better off knowing about this cumulative business. I think I might have preferred to have lived the rest of my life in blissful ignorance of the…dangers of progression.

 

But statistics are just numbers, after all…and numbers can be beaten. And, as my case shows, median times can certainly be beaten!

In conclusion, based on conventional medical statistics, my progression percentage seems to be much higher than I thought (er, if I even thought about it at all…!). So, the question is: am I worried about progressing to active myeloma? Uhm, let’s see now, I will have to get back to you on that one in the year 2029…or 2039…or…

6 Comments

  1. Hello Margaret.

    Let’s hope i can read your blog in 2029. Then i am an old man (77). At this moment your blog gives me a lot of good information.

    Regards

    Hans

  2. Sometimes too much information is not a good thing. Plus….. Yo do not fit in the box. So, stop stretching your math abilities and smile! We will be watching the puffins in 2029, laughing!

  3. Statistics are not good stuff for us.
    It is depending from your age, your personal condition, the cell morphology and zytology of your myeloma cells, nodular or diffuse condition of your myeloma in the bones, osteolytic processes (hot spots) and the myloma cell proliferation rate……..!

  4. Statistics can be your friend. Everytime we get a lab result from our doctor we compare our results to the reference range on the report. These reference ranges are based on statistical samples of “normal” people. Without these statistics, we would have nothing to compare our results to. If we understand the science of statistical analysis we can use statistical techniques to our advantage. If we plot our data and use the power of our computer to fit a trendline (or a more complex function) to our data, we can filter out the normal ups and downs from the data and get a much clearer picture of what is actually happening. For example, if we start taking curcumin on a given date and subsequent data shows a change in the slope of our m spike values, we have statistical evidence that the curcumin is working. Without the statistical curve fitting, the change may be buried in the normal scatter in the data. So statistical techniques offers us a very powerful tool to use to our advantage. All we have to do is use it.

  5. Hi Margaret!

    I haven’t posted here before, but I just came across this post of yours during a search I did on Google on “smoldering MM progression”. I have smoldering MM myself [ nearly 9 years].

    I just wanted to say that I think that you have misunderstood the info on progression percentages, pretty much completely! I hope you don’t mind my saying that, since it is actually VERY good news for you! It works like this …

    “The overall risk of progression was 10% per year for the first 5 years, approximately 3% per year for the next 5 years, and 1% per year for the last 10 years.”

    What this means is that in year 1, 10% of the group of smolderers progressed to full MM, same in each of years 2-5. Then, after that, of those who were left in the group, in each of years 6-10, 3% of the group progressed. Next, again out of those who were left, only 1% of them progressed each year thereafter. So basically, the rule is “the longer you have been smoldering, the more successful you will be at staying in the smoldering state”, statistically speaking and in layman’s terms.

    You don’t accumulate [ ie. add ] the percentages as you go along. For example, if you make it as far as year 6, then your chances of progressing during year 7 are 3%.

    I hope this cheers you up!!!

    best,

    Kate

  6. Hi Kate, in fact, some time after I published this post, a number-savvy blog reader wrote me a private note containing more or less the information that you include in your comment. I meant to post about it, but, as is well known!, I have a hard time dealing with statistics et similia, so I kept postponing the matter…then, I regret to say, forgot about it entirely. Until now. I am very grateful to you for bringing up the subject again and straightening it out for all of us, and in such a clear manner.

    I would just like to note that I have never claimed to be a statistics expert. Hah. On the contrary, numbers make me extremely queasy. That is why I was easily convinced that my original interpretation of the study was wrong…when in fact it was not.

    Well, you have reminded me and indeed inspired me to take another poke at this study, based on the new information I have at my disposal. As soon as possible. Thank you very much for that!

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