Steroid use was intended to be kept at a minimum (2mg qd) and STRONGLY recommended to not be used 10 days before and after DCVax immunization - so 21 days. At other times, the patients could take small amounts of topical or inhaled corticosteroids - less than 0.75 mg.
Additionally, the trial would control for that because it is randomized, meaning both the control and treatment arms were subject to the same conditions.