A Reminder About Survival Statistics

Happy New Year, everyone! Here's hoping that 2022 is an excellent year for all of us. We deserve a good year.

I wanted to start off the new year by looking at an article the journal Haematologica called "Prospects in the Management of Patients with Follicular Lymphoma Beyond First-Line Therapy." It's one of those articles that I like, where a Lymphoma expert or two will look at "where we are" in terms of treatment. I thought that would be a nice way to start the year. 

And I may still do that for the next post. However, the first sentence of the article's Introduction made me smile:

"While the median overall survival (OS) of patients with follicular lymphoma (FL) was under 10 years over two decades ago, the vast majority (~80%) of patients diagnosed today are likely to be alive 10 years after their initial diagnosis, and their expected median OS may exceed 20 years."

This seems like a good excuse to write a reminder to everyone about just what Median Overall Survival means, and why it's important. And if you're new to Follicular Lymphoma and/or the blog, it's good for you to understand what Median OS is, and whether you're understanding it in the hopeful ways you should. 

I was diagnosed in January 2008, and I remember reading then that the median overall survival for FL was 8-10 years. A family member probably read the same easy-to-find source, and wrote to tell me how worried he was when reading that. I was worried, too. I was 40 years old with three kids (the oldest was 10) and I wanted to see them grow up. And now I find out that I'll die at 50. The day I read that was not a good day.

Of course, both my family member and I were reading that statistic wrong. It's a much more complex (and more hopeful) statistic than that. Keep reminding yourself of this phrase: Statistics are not destiny.

It's important to understand the two parts of "Median Overall Survival." The first is the word "median." In statistics, the median is the exact middle of a group of data points. In other words, suppose we wanted to find out how long Follicular Lymphoma patients lived after they were diagnosed. (Which is exactly what we want to find out here.) We could look back at the records of 1001 FL patients and find that information. Then we line up all of those numbers side by side, from the smallest number (position number 1, maybe 6 months) to the largest (position number 1001, maybe 50 years). That's 1001 numbers. Now we look at the number that in the exact middle, whatever the number of months or years is -- the number in position 501. That's the median, the exact middle. There are 500 numbers before it in our list, and 500 after it. 

That's different from the "average" or "mean."

Now look at what the authors of the article are saying -- "The expected Median Overall Survival may exceed 20 years."

That means that half of FL patients will die less than 20 years after they are diagnosed. BUT it also means half will live longer than 20 years. 

Here's why that's especially important: The median age for FL diagnosis is 65. There's that word "median" again. That means half of FL patients are diagnosed when they are younger than 65. And half when they are older than 65. 

Put those statistics together. Someone diagnosed at 65 has a 50/50 chance of living for more than 20 years. (And remember, too, that the "less than 20 years" could be 6 months, but could also be 10, 15, or 19 years.) Someone diagnosed at age 65, then living 20 years, will have roughly the same survival rate as the general population. 

I find great comfort in that. There's no guarantee, of course, that any of us will live to any particular age, but it also means that there's no guarantee that we'll die sooner than we'd like, either.

Two more important things to consider. The second half of that phrase, the "Overall Survival" part, means that the statistic is looking at when people die. It doesn't matter what they die of. It could be of Lymphoma, or a secondary cancer, or complications from treatment. But it could also be from a heart attack, or a car accident, or eating a bad banana. That's what they mean by overall survival. There is a statistic used to measure death from the actual disease, but it's rarely used because Overall Survival is much easier to measure. 

I find that comforting, too. You might have heard or read someone say that many FL patients will die with the disease, not from the disease. That's what the "Overall Survival" statistic is getting at. For many patients, they will be diagnosed at 65, live 20 years (a "normal" lifespan), and die from some other cause. 

One final important thing to note -- this isn't the first study to say our Median OS is around 20 years, and they usually hedge a little by saying "around 20 years" or, in this case, "may exceed 20 years." They never give an exact figure. And there's a good reason why -- no one knows, and for a very positive reason. Not enough people have died yet to measure it.

If we need 1001 people to die before we can measure median OS, and only 800 of them have died, then we can't measure the median yet. We can guess that's it's about 20 years, but it may be higher. And given the trend since the last time they measured, it might very well be higher. Treatments are better then they were in the past, and they continue to get better. (That's the actual point of the article above.)

So here's the lesson from all of this. Being diagnosed with Follicular Lymphoma is awful. Treatments, even the least aggressive ones, are also awful. Watching and waiting, whether it's for the first treatment or between treatments, is still awful. 

But if the goal is survival -- staying alive for as long as possible -- we're all in a much better place today than FL patients were 20 years ago, and we're likely to be in an even better place as time goes on.

Statistics are not destiny. You can't look at a bunch of numbers that say something about a bunch of random people from the past, and expect to learn something about yourself in the present. They just don't work that way.

But that doesn't mean we won't al look at statistics and wonder what they say about it. Numbers seem so definite and sure. 

When I've been depressed about my diagnosis, statistics were somehow part of the cause. If that's the case with you, then you have two options. First, stop looking at them. Or second, remind yourself of what the numbers really mean, and that statistics aren't destiny. Your life is your own. May it be a long, happy one.

I'm looking forward to 2022.

I hope you are, too.