Something About Statistics and Cancer
I am something of a statistician, having endured five semesters of post graduate statistics and research methodology classes while working on my doctorate. As part of that education I read an article by Stephen J. Gould discussing mortality statistics and cancer survival. Wikipedia summarizes the contents and force of that article as follows:
In July 1982, Gould was diagnosed with peritoneal mesothelioma, a deadly form of cancer affecting the abdominal lining and frequently found in people who have been exposed to asbestos. After a difficult two-year recovery, Gould published a column for Discover magazine, entitled, “The Median Isn’t the Message”, which discusses his reaction to discovering that mesothelioma patients had a median lifespan of only eight months after diagnosis. He then describes the true significance behind this number, and his relief upon realizing that statistical averages are just useful abstractions, and do not encompass the full range of variation.
The median is the halfway point, which means that 50% of patients will die before eight months, but the other half will live longer, potentially much longer. He then needed to determine where his personal characteristics placed him within this range. Considering that the cancer was detected early, the fact he was young, optimistic, and had the best treatments available, Gould figured that he should be in the favorable half of the upper statistical range. After an experimental treatment of radiation, chemotherapy, and surgery, Gould made a full recovery, and his column became a source of comfort for many cancer patients.
The whole point of Gould’s position is that the median, which in the case of cancer is highly skewed to the left due to the fact that many cancers are not discovered early making the overall statistic biased toward terminal patients discovered in the late stages of the cancer, as the proper statistic, rather than the mean or average, is a very powerful statistic. Mortality statistics begin with the day of diagnosis, not the time of the onset of disease. So my diagnosis places me in Stage 1, while that could have been, and may still be, Stage 4, depending on the presence of cancer cells outside of my prostate. If, in fact, I am truly in Stage 1 then my chances for survival of this particular cancer are far greater than if I fall into Stage 4. Because mortality statistically begins at the time of diagnosis, there is a significant bias toward the later stages of cancer where treatment is often unsuccessful.
Taken in total as I look at the mortality statistics and my own adenocarcinoma of the prostate, I can take some comfort in the fact that the cancer was discovered quite early and I am relatively healthy for a 69 year old male. With the sole exception of some significant osteoarthritis and well controlled atrial fibrillation, my health is quite good. The fact that scans do not indicate any metastasis is also a good sign; the fact that the CAT scan is inconclusive around the groin area muddies those waters a bit but a resection of the lymph nodes around my prostate will either rule out or confirm a metastatic migration of the cancer. Only time will tell if the Stage P1c is a correct stage diagnosis.
As things stand at this very moment, I have a very good statistical probability for long term survival. In probabilities, however, it is black letter that if something can happen it will. As an example of probability I can relate the time there were ten people left in a poker tournament at Caesar’s Palace and the last nine players would get paid. I had three nines after the flop with two in the hole at a table of 5 players. I went all in, expecting to collect the chips in the pot without opposition. Everyone folded except one player who had three-3s. I was a 99% favorite to win that pot and double up almost assuring that I would be in the final nine. My opponent had only one card in the deck, the final 3, to win the hand unless I got the final 9. The very next card to come on the turn was that 3, the 1% possibility happened and I lost the hand and was knocked out of the tournament. Probability is good when it is in your favor but it is never a sure thing.