Suggest Treatment For A Kidney Condition

My daughter (age 32) had a CAT scan done that shows (according to a Urologist appt mt. today) a 3cm calcification on the Left kidney. She is an otherwise healthy non-smoker, minimal wine drinker, who shows no symptoms of blood in urine, pain in that area, etc. She is not overweight and regularly exercises. She is scheduled for an MRI next Tuesday and is freaking out (me too) after the Cancer word that was thrown out by the emergency room Dr. when she was seen for vomiting and diarhrea last weekend which turned out to be a virus. How likely is it that this calcification is really cancer or cancerous? I know the MRI will offer much more info than we know now, but today s Dr. visit gave her no information or comfort at all.