Smoking anything can cause ill effects. Marijuana smoke contains about the same amount of carcinogens as tobacco smoke, however the difference is that the THC in marijuana acts as an anti-cancer agent, stunting the growth of, or possibly even preventing cancer before it starts. Regardless, smoke inhalation in and of itself if detrimental to the esophagus and lungs no matter what, and a healthier choice would be to use a vaporizer as much as possible.