What is the probability of a suspicious mole being cancerous during biopsy?

100% or 0%: Don't guess odds. A suspicious mole needs to come off. It's either cancer and your life is probably saved, or it's inconsequential. Neglect a suspicious lesion, and there's a fair chance you will pay with your life. A dermatologist can guess malignancy with pretty good accuracy in a suspicious mole, but it's never certain and criteria for moles that should come off are basically scientific.