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Cancer mortality rates in the United States had their biggest drop recorded between 2016 and 2017, according to an analysis by the American Cancer Society.
Cancer death rates in the US UU. They have gradually decreased over approximately three decades, usually around 1.5% per year. But during the last study period, the cancer mortality rate fell by 2.2%, "the biggest drop in a single year," says Rebecca Siegel, scientific director of surveillance research in cancer society.
"It seems to be driven by the accelerated decline in lung cancer mortality," says Siegel. That is "very encouraging, because lung cancer is the leading cause of cancer death in the US, causing more deaths than breast, colorectal and prostate cancers combined."
"This is unequivocally good news," says Dr. H. Gilbert Welch, principal investigator at the Center for Surgery and Public Health, at Brigham and Women's Hospital in Boston. He was not involved in the analysis.
What is behind the decline? In part, smoking rates have steadily declined, which means that the greatest risk factor for lung cancer has declined significantly. New cancer treatments are also playing a role, says Siegel.
However, advanced lung cancer remains deadly. People diagnosed with lung cancer that has spread to other parts of the body have only a 5% chance of survival for five years. And many smokers and former smokers are not following the advice to get tested with a low-dose CT scan to detect cancer early.
In fact, a recent study found that only 4.4% of people eligible for this screening test (which under the Affordable Care Act is available at no cost) actually underwent a screening test in 2015. Almost twice as many people were tested instead that it was found not to be suitable as a screen for lung cancer: a chest x-ray.
And others that did not conform to the recommendations of the US Preventive Services Working Group. UU. They took the CT screening test anyway. "The number of adults examined inappropriately for lung cancer greatly exceeds the number examined according to USPSTF recommendations," the study notes.
Cancer screening has played a controversial role in cancer trends. PSA mammography and blood tests for prostate cancer identify some types of cancer early, when treatment is usually more effective. But the tests also identify many growths that would never be fatal, a phenomenon called "overdiagnosis."
An article published in the New England Journal of Medicine In October, he delved into this issue to help distinguish between cancer trends that are true improvements and trends simply due to changes in screening practices.
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That problem appears in the latest statistics. The reported number of prostate cancers increased in the 1980s when doctors began to detect it with the PSA test. That led to treating many prostate cancers that would never have turned deadly. Even so, the test detected many types of cancer and the death rate from prostate cancer was reduced by approximately 4% per year.
No more. "The rapid decline in mortality rates over the past two decades has actually stopped," says Siegel.
Siegel says that is partly because the reduced detection of PSA, while preventing many unnecessary treatments, is also finding fewer treatable cancers. "I think there is a great need for a better test," she says.
That plateau is not surprising to Welch, of Brigham and Women & # 39; s, who agrees that it might be time to reassess the detection of prostate cancer. "I think we have reached the decline we will get from detection and treatment," he says. Some types of prostate cancer are more treatable than others and, with recent improvements, he says, "we have obtained the low fruits."
The improvements in cancer treatment are evident when it comes to melanoma, a skin cancer that is much less common than prostate or lung cancer. The new statistics show that melanoma mortality rates have decreased by 7% per year. The report attributes this to a large extent to cancer drugs called control point inhibitors and other new drugs. About 92% of people diagnosed with this cancer are still alive five years later (compared to 19% of people diagnosed with lung cancer).
While the report measures trends in cancer rates (measured as deaths per 100,000 people), that is not the same as tracking the actual number of cases and deaths from cancer. Cancer is primarily a disease of the elderly, and the American population is aging rapidly. So, while rates are declining, the absolute number of cancer deaths is not.
"We have more than 600,000 cancer deaths in this country every year, and that number continues to grow," says Siegel.
And with the increasingly expensive treatments, that is a challenge not only for people but for the entire health care system.
A detailed analysis of the statistics will be published on Wednesday in CA: a cancer magazine for doctors.
You can contact NPR scientific correspondent Richard Harris at firstname.lastname@example.org.