Sunday, October 23, 2005

50 percent risk reduction in 20 percent of women

ABC News and host of other news outlets reported recently (or re-reported, it seems to me) that studies are showing that herceptin is a revolutionary cancer drug in the fight against breast cancer, promising a 50 percent risk in the reduction of a relapse in 20 percent of women with breast cancer.

If you're still with me at all, I'm wondering whether you find this reporting to be as confusing as I do.

First, what is a 50 percent risk in the reduction of relapse? In order to answer that question, I guess you have to know what the risk of relapse is in the first place. Then, you divide it by 50 percent. In my case, WITHOUT chemo and JUST surgery, my risk of a relapse would have been about 40 percent. WITH chemo, that risk went down to about 25 to 30 percent. With the addition of radiation, that risk went down further to somewhere in the low 20's, let's say 22 percent. None of that accounts for cancers that are either hormone-driven or not. Hormone-driven cancers (cancers which use estrogen or progesterone, or both, as a growth factor) tend to have better outcomes, although I have never heard any "hard" numbers on this. Further, the MORE hormone-driven a cancer is (again, measured by a percentage), the better the outcome (this may be because hormone-driven cancers respond to hormone therapy, or it may be due to other factors, such as WHO gets hormone-driven cancers in the first place). But let's give me a few percentage points on that, for good measure, since my cancer was estrogen and progesterone "positive" (up to 65%, whatever that actually means). So, let's say my risk of relapse was 18 percent. is where the tricky part comes in (because all of the above is not tricky at all, no). Herceptin is said to reduce the risk of relapse by 50 percent in 20 percent of women with breast cancer. For me, that would reduce my risk of relapse to less than 10 percent. I'll take it (arm raised, hand waving furiously)!!!!!

But who is the 20 percent that Herceptin will benefit? Am I part of that 20 percent? The news reports don't really explain this little and yet entirely significant bit of detail. But I might be able to shed some light, based on disussions I have had with my doctors. Before I do, remember, I'm just Yoga Chickie, not Yoga Chickie, M.D., so this is not intended to replace the advice and counsel of your doctor (as if).

What the news reports don't tell you is that some percentage of all breast cancer patients are designated as "positive" for the "her2neu" growth factor. Pre-Herceptin, this was very very very bad news. The day I found out I was her2neu positive, I cried bitter tears. I was standing outside the Herbert Irving Cancer Pavillion at Columbia, talking on the phone to my oncologist (I have no idea why I was on the phone with her when her office was right upstairs), and she told me that on both available tests for the her2neu factor, my cancer had proven to be "triple positive" or "+3" or "her2neu+++". I burst into tears - worse than when I first found out that I had breast cancer. And I cried all the way up to her office, at the security guard's desk, in the elevator, at the receptionist's desk. It was a bad scene. It may be that I was simply tired of getting bad news. It may be that I had started to get my hopes up when I had found out earlier that week that my cancer was "highly" hormonally positive (good news, remember). Or it may be that I knew from anecdotal evidence how so many women whose cancers were found to be her2neu+++ were sick...really sick...and how so many of those women weren't surviving.

But fairly early on in the course of my treatment (late 2002), news was starting to come out...very early news...that suggested that a drug called Herceptin, when added to the existing breast cancer chemotherapy protocol, could vastly reduce the risk of breast cancer recurring....BUT this was only true in women who were HIGHLY her2neu positive - triple positive - like me. And what percentage of women with breast cancer are her2neu+++?

I believe it is 30 percent. So, knocking out all of the women who can't benefit from Herceptin in the first place, we are starting out with 30 percent. In order for 20 percent of all women with breast cancer to benefit from Herceptin, wouldn't 2/3 of the women who take Herceptin have to benefit from Herceptin? And if that is the case, what does it mean "to benefit" from Herceptin? Don't we either relapse or not? I mean, what difference does it make if I have a 9 percent chance of recurring or an 18 percent chance of recurring, when either I will or I won't?

It's been a long time since I have been called upon to do any sort of complicated math, and it is entirely possible that my math is off. And even if it isn't, none of this is clear to me anyway. I wish I had a better grasp of what the news reporting is actually saying. But I do know that the news is good. Herceptin is helping a lot of women to stay disease free - including me, it seems, knock wood, kinahura, puh-puh-puh.

And I guess that has to be good enough for me.



Susan said...

Wow, that is very confusing math.
It is always funny the percentages they report in the news.
Percentages and polls can always be manipulated for whomever, who needs to prove whatever. Did that make any sense? LOL!
I am glad it's working for you!

yoga chickie said...

Yeah, it definitely makes sense. In fact, you said in three sentences what I took sixteen paragraphs (or something like that) to say. Nice succinctness, Susan!!


Susan said...

I always hated typing, it has forced me to get to the point!

He's Dead, JIm! said...

Medicine is funny with statistics. Many of the papers published in peer-reviewed journals have or use the wrong statistics. Regardless of what the aggregate numbers say, it always comes down to "Will this drug work for ME? And there is not a way to quantify that.

In general, stats are not the best way to make personal treatment decisions. One needs to weigh individual risks and benefits and to decide with one's doctor and one's family based on those. As I am fond of saying "A one percent chance does not mean one percent of you. It means that if it's you, it's one hundred percent of you."

Thanks for another great post...

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Northern Westchester, New York, United States
I live by a duck pond. I used to live by the East River. I don't work. I used to work a lot. Now, not so much. I used to teach a lot of yoga. Now not so much. I still practice a lot of yoga though. A LOT. I love my kids, being outdoors, taking photos, reading magazines, writing and stirring the pot. Enjoy responsibly.


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