Within the first 12 weeks after completing chemoradiation, an increase in contrast enhancement cannot be called Progressive Disease (PD) unless the new enhancement is outside the radiation field or proven by biopsy. This prevents prematurely stopping effective temozolomide due to harmless radiation-induced inflammation.

To achieve a CR or PR, the patient must be off corticosteroids (or on a stable/decreasing physiological dose). Steroids shrink blood vessels, reducing contrast leakage and falsely improving the scan without killing a single tumor cell.