If that's indeed true... The bowel cancer survival rate after 5 years is 95% if teated early enough.
But, speaking as a cancer survivor myself (4.5 years) that assumes that they are in remission. Either he's in remission (effectively 'cured' after 5 years and being monitored) or he still has cancer after 8 years (in which case they can't cure it and he's being treated to prolong his life and would probably be seriously ill by now).
Being blunt... after 8 years either he's cured, being monitored and using it for sympathy or he's had all the treatment they can give (radio, chemo, surgery), is going to die at some point and needs all the support he can get. Do you know which it is?
EDIT: Sorry, just realised Energize isn't the op