Is white and gray brain matter disorder a form of cancer?

Not enough info: Not sure what you mean by "white and grey brain matter disorder". Grey matter is basically where brain cell bodies (neurons) are, and white matter is mainly the cables (axons) connecting neurons. Sounds like you had an MRI and need to talk with your doctor about what it shows - "white and grey brain matter disorder" is too vague and doesn't tell me anything useful.

No.: White and gray matter are normal components of the brain. There are disorder that affect these tissues, e.g., multiple sclerosis affects mainly white matter, alzheimer's affects mainly gray matter.