avoiding lung cancer

Hello. I am 18 and have been smoking for about a year.I fully understand it increases chances of lung cancer, chest infections, throat infections, coughs, yellows skin (i could go on forever).
However i do not wish to give up, because in spite of all these health drawbacks i genuinly love a roll up.
I smoke 5 american spirit roll ups (pure tobacco, no additives) a day. (morning, before work, work break, after work, and before bed).
I wish for an estimate on the percentage of me getting lung cancer. (eg "you hav a 3% chance before ae of 50").
I also wish to know is there any other way to reduce chance? I always eat good, walk 3.3 miles to work 4 times a week. Does excersize, and healthy food make a difference?
I have also heared on the internet that vitiman B17, found in alot of fruit pips can reduce chances, so i always eat the pips out of my 2 daily apples.
Any help is well appreciated.
Thanks!