I've been a one pack smoker for the last four years. i am 24now. i recently quit and am doing good. are there any chances of lung cancer? what steps can i take?

Congratulations: Good on you for quitting before you have done too much damage. Believe it or not your chances of developing lung cancer or significant pulmonary disease after only 4 pack years is relatively low.

Mild increase. Stop: The increased risk of lung cancer due to smoking is dependent both on genetics as well as lifestyle. The risk due to smoking depends both on how many packs per day but also for how many years one smokes. After quitting risk slowly decreases but not to level as if u never smoked. Some people have a genetic predisposition that requires low exposure. Some lung cancer develops in non smokers. Quit.

Never start again!: Your lung cancer risk is diminishing daily since you've quit smoking. The best thing you can do is to never smoke again and maintain good diet and exercise

Short history: And quiting early means your risk is very low, and survival similar to non-smoker. But, you must never smoke, and avoid those that do smoke - side stream smoke worse than filtered. Genetic issue: egfr mutations (asian, women, non-smokers), alk - these are quite small but show proof of principle that molecular understanding finds results, and some quite specific non-curative therapy.