My wife is going to be getting some health related tests soon, and last night she had a dream where her, myself, and her mother were sitting in a car, a man approached and said our names, as if he knew us, then said yes its cancer but you only need one shot. She asked if he was god but he just walked away.
More than anything, its most probably your wife’s fears about the results from tests projected into her dreams.
My advice would be to acknowledge her fear to her, so that she knows that you understand what she is going through, and hopefully she will feel supported in a time that must be quite stressful for you both.
All the best.