Is there a blood test for pituitary cancer?

Not by itself: A pituitary tumor may be suggested by blood test results that show increased amount of certain hormones in the blood. However, some pituitary tumors do not produce hormones. An MRI of the brain is necessary to diagnose a pituitary tumor. Blood tests will help determine if the tumor is producing hormones.

Possibly: Cancer involving the pituitary gland is very rare. Pituitary tumors are relatively common but they are benign. Since the pituitary gland secretes hormones, there are common blood tests that can help detect abnormal pituitary function which might suggest a tumor.