Men around the world dealing with sexual impotence have been treated for years with the drug sildenafil, sold under brand names including the well-known Viagra. A new Chinese study now suggests that the drug may perhaps also help to save lives. Sildenafil could combat cancer by strengthening a group of key anti-tumour immune cells, according to the study by researchers from China’s Westlake University, Zhejiang University, Peking Union Medical College and Shanghai Institute of...