Oxycodone
"I used this during cancer treatment in 2015 to alleviate the sharp pain in my right lung (tumor). For the worst pain I was taking 2 X 40 mg/day. I was able to wean myself off it after about 6 weeks but now 2 years later the cancer has become active again, so I'll take 20 mg to see how I go. It does cause constipation."