Found this interesting information about essential oils and cancer while I was researching on Cedarwood essential oils.

SESQUITERPENES

Sesquiterpenes are compounds of three isoprene units, which is fifteen carbons and twenty-four hydrogens per molecule- molecular weight 204 amu. There are more than 10,000 kinds of sesquiterpenes. Sesquiterpenes are the principal constituents of Cedarwood (98%), Vetiver (97%), Spikenard (93%), Sandalwood (Aloes) 90%, Black Pepper (74%), Patchouli (71%), Myrrh (62%), and Ginger (59%). They are also found in Galbanum, Onycha, and Frankincense (8%).

Sesquiterpene molecules deliver oxygen molecules to cells, like hemoglobin does in the blood. Sesquiterpenes can also erase or deprogram miswritten codes in the DNA. Sesquiterpenes are thought to be especially effective in fighting cancer because the root problem with a cancer cell is that it contains misinformation, and sesquiterpenes can erase that garbled information. At the same time the oxygen carried by sesquiterpene molecules creates an environment where cancer cells can’t reproduce. Hence, sesquiterpenes deliver cancer cells a double punch-onethat disables their coded misbehavior and a second that stops their growth.

Reference: http://www.rnoel.50megs.com/pdf/theblood.htm