Cancer Research: Cancer mortality declining, partly due to screening

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The number of cancer deaths has declined steadily in the last three decades. Although younger people have experienced the steepest declines, all age groups have shown some improvement, according to research published Aug. 13 in Cancer Research.

“Our efforts against cancer, including prevention, early detection and better treatment, have resulted in profound gains, but these gains are often unappreciated by the public due to the way the data are usually reported,” said Eric Kort, MD, who conducted a study while a research scientist at the Van Andel Research Institute in Grand Rapids, Mich.

The researchers examined cancer mortality rates stratified by age and found that for individuals born since 1925, every age group has experienced a decline in cancer mortality. The youngest age groups have experienced the steepest decline at 25.9 percent per decade, but even the oldest groups have experienced a 6.8 percent per decade decline.

The investigators attributed the mortality decrease to prevention, treatment and screening.

However, incidence rates have continued to rise across many cancer types, as have mortality proportions, with the World Health Organization’s (WHO) assertion that death from cancer will surpass death from heart disease by 2010. While both calculations are accurate, Kort said, they asked the wrong question. In particular, the often-quoted WHO statistic can be misleading.

Richard Severson, PhD, a cancer epidemiologist and associate chair of the department of family medicine and public health sciences at Wayne State University in Detroit, said proportional mortality is calculated in groups of 100.

“When calculating proportional mortality, we start with the assumption that everyone dies of something eventually, so you take 100 deaths and calculate, based on death certificates, what those people have died from,” said Severson, who reviewed the report for Cancer Research.

Cancer will surpass heart disease as a cause of death in 2010 because, while both heart disease and cancer have been declining, heart disease mortality rates have been declining much more rapidly, according to the authors. While cancer incidence rates continue to grow, the decreased mortality across all age groups show the effect of improved screening and treatment.

“In childhood cancer particularly, we’re able to do amazing things with leukemia and lymphoma, which used to be a death sentence, but now we are curing many of these cancers,” Severson said.