After the initial diagnosis of cancer, most patients turn to Google to learn about their disease and inevitably to the statistics of cancer: overall survival, progression-free survival, response rate, risk of side effects, benefits of treatments, etc... It's easy to latch on to a number and see your future etched in stone, but that's not typically the case. There is quite a bit behind those numbers and interpreting them for your individual cancer may help you make better medical decisions.
A great place to start when interpreting cancer studies is the National Cancer Institute's Glossary of Statistical Terms
. Another good resource is the Journal of the National Cancer Institute's Reporting on Cancer Research
. It was written with reporters in mind, but patients will find it very useful when reviewing studies to make treatment decisions.
One person who used his knowledge of statistics and asked his oncologist for help was the blogger of "Yet Another Prostate Cancer Blog
," which is somewhat ironic because I haven't seen that many blogs devoted to prostate cancer. But this is a good one.
Jim was diagnosed with metastatic prostate cancer and has been on treatment for a little over a year. He's a former electrical engineer, so he understands the numbers. Additionally, he asked his oncologist how to apply the statistics of metastatic prostate cancer to his individual cancer.
Survival, side effects, progression, all of these depends on the treatment, the patient,the cancer and a multitude of other factors.
Jim has written a pretty good explanation of how cancer statistics can work for you. Here's a recap below. It's also worth a look at how he shares his psychosocial response to cancer. Jim speaks very openly about side effects and dealing with depression and anxiety during treatment.
What Statistics Can and Can't Tell Us
"Let's get the biggest issue out of the way first. Cancer statistics can't tell us how long we'll live."
Jim writes that the statistics may give us a hint, even a strong hint of how the cancer or patient may react to treatment, but there are no guarantees. After weighing his treatment options and the probability of side effects, he opted for radiation. After talking with several medical professionals who told him the most likely side effect would be mild fatigue, he happened to be in the small percentage who were affected with severe nausea.
How to Re-interpret Cancer Statistics
Jim was able to look at the statistics for metastatic prostate cancer and interpret how they may apply to his individual case. He compared his case with a large randomized clinical trial of men with metastatic prostate cancer and looked at the median survival.
Median survival is the time in a particular study where half of the patients have died and half are still living. If a trial followed 100 patients for 10 years, and the point that half of the patients had died was three years, that's the median survival, even if some patients were still alive after 10 years.
After looking at the median survival of metastatic prostate cancer, Jim noted his metastases were detected early, bone pain was minimal at diagnosis, he responded favorably to hormone therapy, his age (young) and overall health (good)--all of which can increase the probability that he will have a longer survival than the median. However, he also shares that his Gleason score was higher and his cancer may be more aggressive. Taking all of these factors into consideration and discussing them with his oncologist, he got a pretty good idea of where he stood, a process he says took several months.
So, while he had come upon statistics that gave him a median survival probability of 30 months, they ended up with a conservative idea of at least 36 months and an optimistic 84 months, especially with the new treatments that have been approved lately--much better than the original 30 months Jim had originally come across.
"Always keep in mind that with any statistic, it probably needs to be reinterpreted to better fit the individual in question."