This is a question I am stuck on for one of my assignments. I am unsure how to answer.

A clinical trial was designed to evaluate a new treatment for a rare form of skin cancer. The study compared death rates from the cancer after 6 months in a treatment group that received the new treatment and a control group that received another, previously approved treatment.

Someone critiqued the study, arguing that there was a problem with the randomization. They looked at the data and noted that the doctors had actually assigned a much higher number of later-stage (more severe) cancer patients to the new treatment. If this is true, could it bias the results of the study? What would be the expected impact on the results?