The chances of getting Lung Cancer through sexual means has not been described. So there is no reason for you to panic.
The chances of contracting lung cancer maybe possible through passive smoking and has been described. Maybe this is the only way you can spread Lung cancer letting others smoke your cigarettes, by inhaling the smoke.Of course you can not spread it like tuberculosis from person to person. So quite worrying and be happy with your friend.
Dr.M.Jagesh kamath MBBS. Dvd Consultant dermatologist