Life expectancy in the United States has fallen for a second straight year—the first time this has happened in more than 50 years. Despite such difficult statistics, cancer deaths continue to decrease—with the death rate dropping 1.7 percent in 2015, according to a new report by the American Cancer Society.

The recent figure is part of a larger trend, with the mortality rate falling 26 percent in the last quarter-century—meaning approximately 2.4 million fewer deaths in the U.S. According to the researchers, the reduced mortality is a result of improved prevention, detection and treatment. Reduced tobacco consumption is another primary factor.

“This new report reiterates where cancer control efforts have worked, particularly the impact of tobacco control,” said Otis W. Brawley, MD, chief medical officer of the American Cancer Society. “A decline in consumption of cigarettes is credited with being the most important factor in the drop in cancer death rates. Strikingly though, tobacco remains by far the leading cause of cancer deaths today, responsible for nearly three in 10 cancer deaths.”

Key findings include:

• Breast cancer deaths dropped by 39 percent from 1990 to 2015 among women, thanks largely to improved detection.
• Deaths due to prostate cancer were more than halved between 1989 and 2015, declining 52 percent.
• The most common cancers in men include prostate, lung and colorectal cancers, amounting to 42 percent of all diagnoses, while women most frequently face breast, lung and colorectal cancer.
• Breast, lung, prostate and colorectal cancers account for 45 percent of all cancer-related deaths.
• Blacks had a 14 percent higher cancer death rate in 2015 compared to whites, a gap that has narrowed since peaking at 33 percent in 1993

• The most common cancers to be diagnosed in men are prostate, lung, and colorectal cancers, which account for 42 percent of all cases, with prostate cancer alone accounting for almost 1 in 5 new diagnoses.
• The most common cancers to be diagnosed in women are breast, lung, and colorectal cancers, which combined represent one-half of all cases; breast cancer alone accounts for 30% of all new cancer diagnoses in women.

The full study is available through the CA: A Cancer Journal for Clinicians.