In its annual report on cancer, the American Cancer Society shared some good news Wednesday. The death rate for cancer fell by 2.2% from 2016 to 2017, the last year measured. That was the biggest one-year drop ever, and it was fueled largely by a decline in deaths caused by lung cancer, the organization said. New treatments have significantly increased survival rates for lung cancer. and people are smoking less.

The overall death rate declined by 29% from 1991 to 2017. That was largely due to improvements among four major cancers: lung, colorectal, breast, and prostate.

The U.S. cancer death rate fell from 155.9 per 100,000 people in 2016 to 152.4 per 100,000 in 2017 — a 2.2% decline.

“This year is a real standout,” Robert H. Vonderheide, director of Penn’s Abramson Cancer Center, said of the report. While death rates have been declining for many years, he was pleased to see that the speed of the drop is accelerating.

“I think what we’re seeing for the first time is a bend in this curve toward better outcomes for our patients,” Vonderheide said.

He said he thinks the improvements are likely to continue because of gains in prevention, identification, and treatment. He credited immune therapies for cancer for a big part of the drop but said that efforts to reduce and stop smoking are also paying off.

One cloud hanging over the rosier stats is the nation’s obesity epidemic, which could push numbers up. “Obesity is a major cause of cancer,” Vonderheide said. “In Philadelphia, we have some of the highest rates of obesity in the country.”

And the report pointed out that cancer is still the leading cause of death for 40- to 79-year-olds. It’s second to heart disease for people over 80.

The cancer society estimated there will be 1.8 million new cases of cancer diagnosed this year in the United States and 606,520 deaths.

The report did not provide long-term data for cities or states. Vonderheide said Philadelphia has relatively high cancer rates because the city has lots of smokers and possibly because of environmental exposures along the I-95 corridor. The city also has a large population of people, especially Ashkenazi Jews, who are at risk for some hereditary cancers. On the plus side, a high proportion of Philadelphia teens have gotten a vaccine that prevents cervical cancer.

The cancer society estimated that 15,710 people in New Jersey and 27,860 in Pennsylvania would die of cancer this year.

With one exception — lung cancer in men — incidence rates for cancer in general, as well as breast, colorectal, lung, non-Hodgkin’s lymphoma, and prostate cancers, were higher than the national average in both New Jersey and Pennsylvania from 2012 to 2016, the new report said.

In a cancer society report released in 2015, which covered 2007 to 2011, cancer incidence rates were also generally higher in New Jersey and Pennsylvania than in the nation as a whole.

The new report found that Pennsylvania had higher mortality rates than the national average for all cancers from 2013 to 2017, as it did from 2007 to 2011. In New Jersey, overall cancer mortality rates were lower than the national average in the new report and close to the national average for most of the individual cancers analyzed. Mortality rates fell in both states between the two reports. A cancer society spokesperson said the numbers could not be compared directly.

Nationally, lung cancer is still the top cancer killer, but death rates have dropped by 51% for men since 1990 and by 26% for women.

The report said melanoma, a form of skin cancer, has had a particularly strong improvement in survival due to new treatments.

Meanwhile, progress has slowed for colorectal, breast, and prostate cancers, diseases that can often be detected early with screening.

The incidence of other cancers is increasing: kidney, pancreas, liver, oral cavity and pharynx, and melanoma.

The five-year survival rate for all cancers combined diagnosed between 2009 and 2015 was 67%. It was 68% for whites and 62% for blacks.