I smoked hash joints 4-5 years & about 7/day. if i quit will my lung morphology & cancer risk return to normal completely , and if so how long? im 26

Quitters are better: If you were to quit today, you will be better off than quitting 5-10 years from now. The lung changes are usually irreversible but they may not be badly damaged at this time at your age. Your cancer risk approaches the same as a non smokers risk in about 7 years.

Never: While it will be very close to normal after about seven years it is difficult to say conclusively that your risk will ever be the same as someone who never smoked hash cigarettes.

NO: Some early studies, were somewhat misinterpreted in suggesting that the risk goes down to 0. There clearly is residual risk above that of a never smoker; it does not go to 0. The risk diminishes relative to continued smoking, but it never goes down to that of a non-smoker.