That was my first thought, but the article specifically addresses that. It's due to improved treatments for lung cancer. Take lung cancer out of the data and the death rate improved by 1.4% last year, which is basically the same as the baseline 1.5%/year rate that cancer deaths have been dropping since 1991. If it were due to the opioid epidemic, you also wouldn't see that sustained drop over 3 decades - life expectancy in the U.S. has only been falling for 3 years.