It is 60 years since a British doctor first made the link between smoking and lung cancer, and now it seems we may finally be starting to win the battle against nature's most vicious disease. Liz Bonnin explains how cells turn cancerous by blowing high-tech bubbles. Jem Stansfield builds his own radiotherapy gun, Maggie Philbin looks at the latest drugs, and the team are joined by Ground Force's Tommy Walsh, who looks into screening for bowel cancer.