The rate of cancer deaths in the U.S. dropped 27% between 1991 and 2016, according to a new report from the American Cancer Society, amounting to 2.6 million fewer deaths.

Cancer remains the second leading cause of death in the U.S. as of 2016, but mortality rates of the four main cancers—lung, breast, prostate, and colorectal—are declining. This is largely due to advancements in early detection and treatment, plus the decreasing popularity of smoking, Rebecca Siegel, report author and ACS’ strategic director of surveillance information services, told Axios.

This good news comes with the realization that the socioeconomic gap of cancer deaths is growing: poorer women have twice as many deaths from cervical cancer than affluent women, and the lung and liver cancer mortality rate was 40% higher for poor men than wealthier men from 2012 to 2016, says the ACS.

“Although the racial gap in cancer mortality is slowly narrowing, socioeconomic inequalities are widening, with residents of the poorest counties experiencing an increasingly disproportionate burden of the most preventable cancers,” reads the report.

This is largely due to a lack of access to quality health care. Not only are poorer people are “unable to get systematic screenings,” Siegel said, “but treatment options are oftentimes not the highest quality.”