My father in law was recently diagnosed with 2 renal cysts 1 the size of an orange. they do not think they are cancerous. what is the treatment?

Depends: Cysts are very common. They can be benign or malignant depending on how it looks on the scan. If it looks suspicious on ct or ultrasound, radiologist may recommend mri. If multiple cysts are involved, need to rule out polycystic disease.

Watchful waiting: Cysts are usually harmless unless there are many of them or they become cancerous. I suspect that with one cyst this large repeat studies (ultrasound) will confirm lack of growth. Smaller simple cysts dont need this. If the cyst changes then referral to urology for evaluation will be needed. There is no treatment needed now.