If you quit before the cancer is gone, it will start growing again. And when it does, it will come back really fast. So I would not advise him to quit completely until he is certain he is cancer free. There is a blood test called the AMAS test that can detect cancer anywhere in the body as small as the head of a pin. People do not quit taking bloodroot until they get a clear AMAS test. Take it with food to prevent the heartburn. Is he taking anything to rebuild and nurture the liver during his time off from bloodroot? Dandelion, Milk Thistle, Herbal Detox by Herb Pharm, Chinese Herbs and Ayur Vedic Herbs can help him rebuild a healthy liver. Has he done any liver flushes?