4.3cm simple cyst in my left kidney upper & has slowly grown 1.5cm over the past 5 years seen on ct. can this cause epigastric pain?

Unlikely : If this is truly a simple cyst, they are virtually always benign, and a cyst of this size should never cause symptoms. Small increase in size over 5 years should not be a cause of concern at your age. The important thing is to have your physician ask the radiologist to be sure that it is a benign cyst. Usually they are discovered on an ultrasound or a ct scan, and each modality has its criteria.