Your lungs have an almost "magical" ability to repair the cancerous mutations caused by smoking - but only if you stop, say scientists.

Axar.az reports citing foreign media.

The mutations that lead to lung cancer had been considered to be permanent, and to persist even after quitting.

But the surprise findings, published in Nature, show the few cells that escape damage can repair the lungs.

The effect has been seen even in patients who had smoked a pack a day for 40 years before giving up.

The thousands of chemicals in tobacco smoke corrupt and mutate the DNA in your lung cells - slowly transforming them from healthy to cancerous.

The study uncovered that happening on a massive scale in a smoker's lungs even before they had cancer.