The death rate from all cancers in the United States dropped by 25 percent between 1991 and 2014, according to a Cancer Statistics 2017 report released today.

This translates to more than 2.1 million fewer deaths from cancer during those years.

“That’s remarkable public health progress,” Elizabeth Platz, Sc.D., a professor of epidemiology at Johns Hopkins Bloomberg School of Public Health, told Healthline.

Platz said, “better access to care, early detection, and better treatment” of cancer have contributed to the steady decline in cancer death rates in the past two decades.

“But,” she added, “the major driving factor has been the reduction in cigarette smoking in the U.S.”

Over the past decade, the overall incidence of cancer in women held steady. It declined by about 2 percent each year in men. The overall cancer death rate decreased by about 1.5 percent per year in both women and men.

The report also estimates that in 2017 there will be nearly 1.7 million new cancer cases and more than 600,000 cancer deaths in the United States.

The American Cancer Society produces this report every year based on data collected by the federal government.

The report was published online in CA: A Cancer Journal for Clinicians. 2014 is the latest year that cancer mortality data was available for analysis.

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The good and the bad

The largest drops in death rates were for lung, breast, prostate, and colorectal cancers.

But more work is still needed in certain areas.

“We still need to put effort into cancers that traditionally have caused high mortality — ones that tend to be detected late,” said Platz.

One of these is pancreatic cancer. The authors of the report estimate that almost 54,000 new cases will be diagnosed in 2017. More than 43,000 people are expected to die this year from this cancer.

Another cancer that is detected late is ovarian cancer. This year, more than 22,000 women are expected to be diagnosed, and more than 14,000 are expected to die of this cancer.

Platz also highlighted liver cancer as another cancer of concern — one that might be called an “emerging epidemic.”

“That’s a cancer that has been increasing in incidence over time in the U.S., more so in men than in women,” said Platz. “And again, it’s a cancer that tends to result in death.”

The most common risk factor for liver cancer is long-term infection with the hepatitis B virus or hepatitis C virus.

Both of these are preventable — either through the hepatitis B vaccine or avoiding risk factors for hepatitis C such as injecting illegal drugs.

Read more: Get the facts on liver cancer »

Concerns about obesity

More research into ways to detect cancers earlier, and better methods of treatment, will help continue the steady decline in cancer death rates.

But two factors may put the brakes on these gains.

“The epidemic of obesity, and the age at which people are now becoming overweight and obese, is actually worrisome,” said Platz.

Obesity is a risk factor for many cancers, including colon, breast, kidney, and pancreatic cancers. It is also a risk factor for other chronic diseases, such as diabetes and heart disease.

According to the National Institute of Diabetes and Digestive and Kidney Diseases, more than two-thirds of American adults are overweight or obese. More than 1 in 20 have extreme obesity.

“If we could intervene on obesity in the way that we have for smoking,” said Platz, “we could really benefit society.”

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Health insurance concerns

Another factor that could negatively affect cancer death rates, especially in minority populations, is the uncertain fate of the U.S. health insurance marketplace.

Republicans in Congress are moving ahead with plans to dismantle the Affordable Care Act (ACA) — with no detailed replacement yet proposed.

Depending on the outcome, some people may end up losing health insurance.

Some has found that lack of adequate health insurance is linked to later diagnosis of cancer and lower survival rates.

“Having health insurance allows people to get to the doctor for early detection — meaning screening,” said Platz. “It allows people to have access to treatment, both high-quality treatment and treatment in general.”

The authors of the American Cancer Society report cite studies showing that between 2010 and 2015 — when the ACA came into effect — the proportion of African-Americans who were uninsured decreased from 21 percent to 11 percent. In Hispanics, the proportion of uninsured fell from 31 percent to 16 percent.

Although the gap in cancer death rates between Caucasians and African-Americans has narrowed in recent decades, the cancer death rate in African-Americans is still 15 percent higher than in Caucasians.

Loss of stable and affordable health insurance could reopen that gap.

Platz said that if people don’t have health insurance to help offset the costs of healthcare, “it’s likely that cancer rates would go back up because we wouldn’t be able to do early detection of premalignant lesions to the same extent. And that tends to disproportionately affect minority populations in the U.S.”