With her only approved treatment options being chemotherapy and radiation, her father, Brandon Krenzler, chose to treat her with a course of medical marijuana in conjunction with chemotherapy.
Mr Krenzler told the Huffington post that prior to MyKayla's diagnosis, "she was very sick, she was in a lot of pain". Her symptoms included fever, rash, severe coughing and stomach pain, night sweats and a reduced appetite.
MyKayla is now treated with a gram of cannabis oil daily and her father says it helps to restore her appetite and combat some of the effects of her chemotherapy, including nausea. Mr Krenzler says that without the marijuana his daughter "would be sick every single day".
While Oregon law currently permits the use of medical marijuana, some medical experts and researchers argue that the effects of marijuana on the developing brain could be detrimental and lead to a decline in cognitive performance.
MyKayla's cancer is now in remission but, as Mr Krenzler writes in his Cannadad's blog, she still has to undergo "maintenance" chemotherapy for two more years. Her prognosis is a 76.9 per cent survival rate.Related: Dad photographs his daughter's winning battle with cancer