Hi Reg2,

Weirdly, this is my favourite topic - apart from sailing and scuba diving!
There are two reasons for this - professional and personal. 
Before my early retirement I worked for the NHS in an IT/Information capacity.
In 2013 I was diagnosed with stage 4 oesophageal cancer and given between 2 and 6 months without chemo and up to 18 months with, along with a less than 5% chance of survival after 5 years.
13 years later, I am a statistical outlier and excluded from national stats.

Survival stats are:
1. based on average patients, but none of us are average
2. ignore factors such as age, fitness and co-morbidities
3. great applied to large numbers of patients but useless for individuals

I hope this helps!
Dave