Hi, I take frankenscense (Boswelia) in extract form, not the essential oil. I use the essential oil with a diffuser and sometimes on my gums for oral health. There is a lot of research regarding frankensense and cancer. It is a highly anti inflammatory supplement, which is good.
Personally, I'd be careful with the oil. Not all essential oils should be ingested. Here's a good article on the subject:
http://tisserandinstitute.org/frankincense-oil-and-cancer-in-perspective/