Lung Cancer. Used to cure lung cancer?

Dear Sir/Ma'am, I am Kuldeep Dungarwal, a student in Sreenidhi International School. I am currently in 9th grade. Recently I had a biology project where we had to chose a topic like the system of a brain, lungs or any disease. Immediately when heard this news, I chose my topic as Lung Cancer. I chose Lung cancer because this is a very interesting topic, I have searched a lot through different media's about Lung Cancer., but I also want to know more about Lung Cancer from an Expert just like you. So, I would like to ask you a few questions about Lung Cancer. Is Lung Cancer caused mainly because of Smoking? How do X-rays cause Lung cancer and also treat it? What treatments are mostly used to cure Lung Cancer? This is the end of my questions. Thank You for giving me your important time. Your Sincerely Kuldeep Dungarwal