There are growing concerns about the widespread use of PPIs, the acid suppressing family of drugs used to treat indigestion and the most prescribed in the world. They are recommended to be used for weeks in typical cases of heartburn, but most people including Mark, take them for months or years. But one reason why PPIs are being used so widely is to protect the lining of the gut from aspirin and combining these two drugs may also have benefits against cancer. Mark hears preliminary findings on the so called chemo-protective effects of aspirin. And radiotherapy is a crucial part of modern cancer treatment so why does it get so little attention compared to drugs? Plus why radiation and smoking are particularly poor bedfellows.