Small amounts of a cancer-causing chemical have been found in the popular heartburn medication Zantac, as well is in generic forms of the drug, known as Ranitidine. The FDA is not issuing a recall and says patients can continue taking the medication. Zantac's maker says it takes patient safety seriously and is committed to working with the FDA. Dr. David Agus joins “CBS This Morning: Saturday” to discuss what consumers need to know.