Right now there is no research on treating an animal when the pet owner has a history of cancer.  Based on the findings of treatment of pets with cancer, we think it is safe for the pet owner to treat.  When treating a patient, it is suggested to avoid treating the area that either has or had the malignancy. Likewise, when treating a pet, the pet owner should avoid illuminating areas that were affected by cancer with the typical dosages for pets.  Since there is no conclusive research, the safest thing to do is to have another user treat the patient, but based on the current research available, we believe it is safe to treat.