In 2003, Simpson discovered three suspicious spots on his face and neck and was diagnosed with basal cell carcinoma skin cancer. When surgery didn't work, he decided to explore an alternate route; using the same extracted cannabis oil he'd been making and taking orally for over a year on his newly discovered cancer.

Simpson had been treating some health conditions from a previous injury with his cannabis oil when he recalled a study published in the Journal of the National Cancer Institute stating that THC was found to kill cancer in mice. So, Simpson proceeded to apply the oil topically to the cancerous spots on his neck and face and covered them with bandages. In just four days, the skin underneath was healthy and pink. He was healing.