I'm not sure how likely cancer is, but they very rarely use chemotherapy or radiotherapy for thyroid cancer. If she has cancer, they will likely remove the rest of her thyroid, assuming they are only removing part of it now. That will probably cure it.

She might get radio-iodine treatment, if she is at higher risk of recurrence, but that is really just swallowing a capsule. It's a one-off treatment and doesn't make you weak or sick or lower your immune system or anything. It's annoying as you have to isolate for some time afterwards because you are radio-active, but it's not like chemo or anything.

I had thyroid cancer in 2020. I had my operation on the 6th of January and was back at work a month later. I had radio-iodine treatment the end of May and since...well, really that February, it's just meant taking two tablets every morning and having blood tests and a scan every year to be sure there is no recurrence.

I will say some people do have difficulty getting the medication dose right and can experience side effects if it is off, but that is a minority, I think.