When a doctor first suspects a brain tumor, initial testing typically involves imaging such as a CAT scan or an MRI. When initial imaging reveals a mass, it’s important to recognize that it’s far more valuable to do your due diligence than to take immediate action. Ask for a referral to a brain tumor center. That includes specialists in disciplines such as neurosurgery, neurooncology, neurology, neuroradiology, neuropathology, and radiation oncology, who all work together and specialize in the care of brain cancer patients. Advanced imaging is typically helpful in coning down a list of diagnoses, but definitive diagnosis requires a tissue biopsy. In rare cases, treatment is initiated in the absence of a tissue diagnosis. However, in the vast majority of cases, a tissue diagnosis is made through at least a needle biopsy before initiating treatment. If glioblastoma is suspected on initial imaging, a needle biopsy is frequently not performed and a surgical resection is planned. The tissue diagnosis is made on tissue obtained through that surgical resection instead.