Hi, I wanted to add to the responses here. My grandma was diagnosed with breast cancer earlier this year. Her tumor was aggressively growing in the months before starting chemotherapy (she could feel it.) Anyways, for a couple weeks she was taking 10 drops of h2o3 in ~ 10 oz of distilled water, 3 times a day. The tumor stopped growing and by the time chemo started, she noticed that it shrunk. Although she is having conventional treatment now, I do believe the h2o2 was having a significant effect on her from the start, and she continues to take it for its many health benefits, and so do I. OP best of health to your grandfather!