Is It Ok To Delay Surgery For Wide Neck Aneurysm?

my father 50yrs old has been diagnose with wide neck aneurysm of the size 4.5x5.1mm diametre in the sylvian fissure of left MCA. i dont want the surgery.. can it be delayed ? if it can be delayed for another 10- 15 yrs with close monitoring i want to do away with the surgery. surgery or non surgery which is more risky