main cause of lung cancer???

Smoking, exposure to fiberglass in factories, inhaling harmful chemicals....really there is so much pollution anymore you could probably get it just breathing now. It is scary.

My grandpa was just diagnosed with Stage 3 B. He was a smoker for many years plus worked in a factory making wooden handles for shovels and rakes which the wood would have chemicals.

oh thats sad...but if a person smokes cigarette less then 10 cigarettes...can that cause cancer??

Every toxin you put in your body no matter how small the amount increases your risks for certain cancers. Anything inhaled that is considered toxic such as the chemicals in cigarettes (and many other things) will increase risk of lung cancer as it goes straight to the lungs when you inhale it. I only smoked maybe 20 in my life probably less than that but the Dr told me even 1 exposes you to chemicals. Problem is that second and third hand smoke can also expose people to the harmful toxic chemicals and increase risk of cancers.

so how can a person can stop smoking at once???

Its a matter of mind over matter and training your brain to not need the smoking but it isn't easy. Some find it easier than others. My dad quit no problem however my mom is having troubles quitting.