I’m sure your mom is scared. No one wants to be told the diagnosis is cancer and the treatment plan and side effects. If she is at a cancer center, she should have access to the Guidance Department. When my husband was in treatment, a volunteer at the hospital told me to trust the doctors, that they know what they are doing. She also told me to go talk to someone at the Guidance Department.
Other than that, I found that the best way of dealing with the stress is to take it one day at a time. If John had to have an MRI, then we went but we did not then allow our minds to fly to the results on that day. We had to wait for the doctor’s visit and then we would be told. There was no point in fretting as it would only exacerbate the stress. The mindset took me through multiple tricky situations over three years. That’s probably the best way to deal with it.
Wishing you all the very best!