Cancerous Cells Will Clear On Thier Own?

My father-in-law had his gall bladder removed about two weeks ago.  Yesterday he was telling me about his blood work and mentioned that they had found cancerous cells.  He played it off making it sound as though it was no big deal.  He said the nurse told him it was a result of having his gall bladder removed and that as his body adjusted everything would clear up, that this was normal.  Is this really normal??