Cancer death rate in U.S. has now been falling for 25 years

The U.S. cancer death rate has hit a milestone: It's been falling for at least 25 years, according to a report.

Lower smoking rates are translating into fewer deaths. Advances in early detection and treatment also are having a positive impact, experts say.

But it's not all good news. Obesity-related cancer deaths are rising, and prostate cancer deaths are no longer dropping, said Rebecca Siegel, lead author of the American Cancer Society report published this week.

Cancer also remains the No. 2 killer in the U.S. The society predicts there will be more than 1.7 million new cancer cases, and more than 600,000 cancer deaths, in the U.S. this year.

A spokeswoman for the Canadian Cancer Society, Rosie Hales, said they're seeing the same general trend in Canada, although there are some differences.

Cancer deaths rates in Canada peaked in 1988 and have been decreasing since then, according to the society. "This decrease is largely driven by the progress we've made with lung cancer and prostate cancer in males, breast cancer in females and colorectal cancer in males and females," Hales said in an email.

It's estimated 206,200 new cancer diagnoses and 80,800 deaths from cancer occurred in Canada in 2017, according to the society's latest report, Canadian Cancer Statistics 2018.

A breakdown of the U.S. report says:

Dropping since 1990s

There's been a lot of bad news recently regarding U.S. death rates.  In 2017, increases were seen in fatalities from seven of the 10 leading causes of death, according to recently released government data. But cancer has been something of a bright spot.

The cancer death rate in the U.S. was increasing until the early 1990s. It has been dropping since, falling 27 per cent between 1991 and 2016, the American Cancer Society reported.

A decline in lung cancer cases is the main reason. Among cancers, it has long killed the most people, especially men. But the lung cancer death rate dropped by nearly 50 per cent among men since 1991; a delayed effect from a decline in smoking that began in the 1960s, Siegel said.

Prostate cancer

The report has some mixed news about prostate cancer, the second leading cause of cancer death in men.

The prostate cancer death rate fell by half over two decades, but experts have been wondering whether the trend changed after a 2011 decision by the U.S. Preventive Services Task Force to stop recommending routine testing of men using the PSA blood test. That decision was prompted by concerns the test was leading to overdiagnosis and ​overtreatment.

The prostate cancer death rate flattened from 2013 to 2016. So while the PSA testing may have surfaced cases that didn't actually need treatment, it may also have prevented some cancer deaths, the report suggests.

Obesity

Of the most common types of cancer in the U.S., those with increasing death rates are linked to obesity, including cancers of the pancreas and uterus.

Another is liver cancer. Liver cancer deaths have been increasing since the 1970s, and initially most of the increase was tied to hepatitis C infections spread among people who abuse drugs. But now obesity accounts for a third of liver cancer deaths, and is more of a factor than hepatitis, Siegel said.

The growing obesity epidemic in the U.S. was first identified as a problem in the 1990s. It can take decades to see how a risk factor influences cancer rates, "so we may just be seeing the tip of the iceberg in terms of the effect of the obesity epidemic on cancer," ​Siegel said.