My dad is 45 years old and turns 46 on June 21. He has been smoking ever since he graduated from college, at age 25, turning 26. So he has been smoking for about 20 years. He quit for almost a year when we first moved to America, but he started again. So about 19 3/4 years he has been smoking. He has quit now, at age 45 and he hasn't smoked for almost a month now. What is the chance of him still getting lung cancer?