When reporting cancer outcome statistics, the most common thing you are told by oncologists are 5-year outcome data (i.e. survival, recurrence, etc.) But those results do NOT apply to you. They only apply to a population of patients.
Dr. Maurie Markman (of CTCA) writes this:
“What is the statistical probability a particular patient will achieve a 5-year goal if she or he already has lived 1 or 2 years from diagnosis without having experienced progression of the disease? Is it appropriate to provide that patient with the same 5-year survival data simply because that is what is available in the literature or public databases“
In my opinion, the answer is ‘ NO.’
Dr. Markman goes on to say, “In fact, in a recent provocative paper examining what has been labeled “conditional disease-free survival,” investigators examined the statistical likelihood that an ovarian cancer patient would not have progression of cancer based on the duration of time she had already not exhibited evidence of progression. In this analysis, at diagnosis, the probability that an ovarian cancer patient would be disease-free at 5 years was 44.6%. However, if the patient had gone 2 years without experiencing evidence of recurrent disease, the 5-year disease-free survival increased to 80.5%; and if the individual did not exhibit progression for 3 years, the 5-year figure was 92.4%. Of course, each of these figures is substantially superior to the baseline recurrence risk of more than 50%. Similarly, the evaluation revealed that the statistical probability that an individual who had already experienced 1, 3, or 5 years of remission would remain disease-free for an additional 3 years increased from 48.2% at diagnosis, to 63.8%, 90.4%, and 97.7%, respectively. Again, these figures are quite different from, and substantially more favorable than, the baseline recurrence value.”
I think that this is an excellent point for patients to recognize, and studies should incorporate this type of relative outcome reporting.
