On September 10th, an international tobacco harm reduction media event was held in Sofia [...] Prof. Khayat was one of the most pre-eminent speakers. He has been Head of the Medical Oncology Department at La Pitié-Salpétrière Hospital in Paris and President of the French National Cancer institute. He said that the number one risk factor for cancer worldwide is smoking, which even surpasses excessive alcohol use and high body mass index. To understand more precisely how smoking causes diseases, one should understand cancer is. [...]