Some Thoughts About Overall Survival in FL

This is sort-of related to ASH, though it isn't looking at one of the abstracts, like I usually do this time of year.

I've been reading the ASH abstracts (over 200 of them) looking for the ones that I find interesting or worth talking about in some way. And I came across a few that mention OS, or Overall Survival for Follicular Lymphoma. It's worth talking again about OS and what it means.

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The ASH abstracts are basically summaries of what the presentation is going to be about. They mostly start off with an Introduction -- some description of the general topic of the presentation. The rest of the abstract gets into the specifics. Some of the Intros start off really general, describing what Follicular Lymphoma is, and, if it's appropriate, giving some statistics about things like OS.

As I was reading, one of the things that I found really interesting was the different ways that various researchers talked about FL and OS. For example, these are from 4 different Introductions:

• "Most patients experience an indolent disease course, with median survival of over 15 years."
• "Follicular lymphoma (FL) is the most common indolent lymphoma with a median survival approaching 20 years."
• "Follicular lymphoma (FL) is usually an indolent malignant B-cell lymphoma with median survival now approaching 20 years in the rituximab treatment era."
• "Despite an indolent course, it remains an incurable disease and the overall survival (OS) is 70-80% at 8 years in the rituximab era."
• "The clinical course of follicular lymphoma (FL) is characterized by recurrent relapses and progressively shorter remissions, with many patients surviving beyond one decade from initial diagnosis."

Now, to be clear, these are written for other oncologists and hematologists -- experts in blood cancer. And, to be clear, they have reasons for presenting these numbers the way they do. It helps set up the point they want to make about the research they did and why it's important. And those numbers all mean basically the same thing, if you look at them closely enough. But it's strange that they are all presented differently.

And I'm looking at these numbers as a patient. Patients read numbers differently than doctors do.

I did a quick Google search, and it showed me various sites (all up-to-date and reputable) that give the median OS for FL as 19 years; 14 years; over 20 years; "historically 8-10 years" but longer recently; and "Around 10 years," but ranging from 1 year to 20 years.

It's all very confusing, isn't it?

And what makes it worse is that, especially for someone newly diagnosed, survival numbers are really, really important. It's one of the first questions we ask -- "Cancer? Oh no! How long do I have?!"

Unfortunately, the media OS isn't going to give you an answer.

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So what's the deal with Overall Survival?

First of all, the reason the ASH abstracts are kind of fuzzy is that there isn't really agreement on what the median OS is for Follicular Lymphoma. I have read that it's because many patients live for a long time. It's hard to calculate a median survival (a measure of when people die) when people are staying alive. So that's a good thing.

The numbers are also kind of fuzzy because different studies have come up with different figures. There are a lot of factors that can mess with that number -- the age of the patients, the treatments they have had, how long ago they were diagnosed, and how treatments have improved recently. So it's easier to say "approaching 20 years" or "over 15 years" or (to be especially vague) "beyond one decade" than it is to give a definite number.

But, as patients, none of that really eases our minds. There's a big difference for us between 10 years and 20 years.

So here are some things to keep in mind about Overall Survival, especially if you're one of those folks who was recently diagnosed, or who obsesses over numbers. I hope it eases your mind just a little.

First, OS is usually expressed as "Median Overall Survival." And "median" matters. It doesn't mean "average." In statistics, the median is the middle of a group of numbers. So if the median OS for Follicular Lymphoma is 20 years, and they came to that number by looking at 1000 patients, that means that 500 of them will live for less than 20 years, and 500 will live for more than 20 years. On the "more" side, that could go on for a long, long time -- 21 years, 25 years, 50 years. There is no upper limit. A median OS of 20 years does not mean you have only 20 years to live. It meas you have a 50% chance of living longer than that -- maybe much longer.

Second, "Overall Survival" is just that -- the number of patients who have survived overall. It measures death by any cause. That includes lymphoma-related deaths, but also death by heart attack, or by snake bite, or by getting hit by a double-decker bus. It's easy to think of that number as being just about lymphoma, and that makes lymphoma seem so much scarier. But OS includes any reason for not surviving.

Third, keep in mind that the average age at diagnosis for Follicular Lymphoma is somewhere in the 60s. That puts the OS number in a different light, especially for those of us who were diagnosed at a younger age (like me, diagnosed at 40). Right now, in the United States, a male who is 60 years old has a life expectancy of 83.3 years. He will live, on average, another 23 years. Compare that to the OS for a patients diagnosed at 60 with FL: about 80 years. Not a huge difference. In fact, you will sometimes see discussions of FL survival point out that it is "approaching the general population."

And keep in mind that the numbers are different for different age groups. People under 60 (I have read) have a higher OS than the overall median. We can expect, statistically, to be on the part of the scale that goes way beyond 20 years.

One more thing: this OS number changes. All the time. It has risen steadily in the almost 10 years that I have been a patient. I remember a loved one emailing me and my wife in a panic because he'd looked up Follicular Lymphoma and Wikipedia said the median OS was 8 to 10 years. So it has about doubled since then, thanks to better treatments and better ways of measuring. I expect it to go up some more in the next 10 years (and I expect to be around to watch it).

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Here's the point I want to make:

Try not to obsess about numbers.

I know it's hard. Numbers seem so sure, and so final, and so unchanging. 2 + 2 always equals 4. In our emotionally-charged brains, it's easy to go from that to thinking "and therefore, I have only 20 years to live" (or 14, or 8 to 10).

Numbers aren't as sure as they seem to be. The huge range of OS statistics out there should prove that. And if experts are only willing to give fuzzy numbers, that should make it even more likely.

A median or an average says nothing about each of us as individuals.

The best we can do is live a good life, enjoy every day, be kind to one another, make the world a better place, learn as much as we can about our disease, and be active in the decisions that get made about our healthcare.

And have dessert.

So go do all of those things.