Grand Rapids, Mich. (Aug. 13, 2009) - 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 a recent report in Cancer Research, a journal of the American Association for 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, M.D., who completed the study while employed as a research scientist at Van Andel Research Institute (VARI) in Grand Rapids, Mich.
Cancer mortality rates are usually reported as composite age-adjusted rates. These rates have been declining modestly since the 1990's. However, these statistics heavily emphasize the experience of the oldest Americans for whom mortality rates are the highest. As a result, trends emerging in younger Americans can be concealed.
As an alternative to age-adjustment, Kort 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 public often hears about incidence rates, which continue to rise across many cancer types, or mortality proportions, with the World Health Organization's assertion that death from cancer will surpass death from heart disease by 2010. Both these calculations are accurate, Kort said, but they ask the wrong question. In particular, the often-quoted WHO statistic can be misleading.
Richard Severson, Ph.D., a cancer epidemiologist and associate chair of the Department of Family Medicine and Public Health Sciences at Wayne State University, 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. And while it's true that cancer incidence rates continue to grow, the decreased mortality across all age groups shows the effect of improved screening and treatment.
"In childhood cancer particularly, we're able to do amazing things with leukemia and lymphoma that used to be a death sentence but now we are curing many of these cancers," Severson said.
"This study focuses on an aspect that has been overlooked in determining whether we've had a significant impact on cancer mortality," said George Vande Woude, Ph.D., head of VARI's Laboratory of Molecular Oncology. Vande Woude helped conceive of the project and is one of the study's authors.
Vande Woude and Kort, currently a medical resident at Helen DeVos Children's Hospital in Grand Rapids, worked in collaboration on the project with Nigel Paneth, M.D., of Michigan State University's College of Human Medicine, departments of Epidemiology and Pediatrics and Human Development. The project was funded by a grant from the National Institute of Child Health and Human Development and Van Andel Institute.
About Van Andel Institute
Established by Jay and Betty Van Andel in 1996, Van Andel Institute (VAI) is an independent research and educational organization based in Grand Rapids, Mich., dedicated to preserving, enhancing and expanding the frontiers of medical science, and to achieving excellence in education by probing fundamental issues of education and the learning process. VARI, the research arm of VAI, is dedicated to probing the genetic, cellular and molecular origins of cancer, Parkinson and other diseases and working to translate those findings into effective therapies. This is accomplished through the work of over 200 researchers in 18 on-site laboratories, in laboratories in Singapore and Nanjing, and in collaborative partnerships that span the globe.
The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, AACR is the world's oldest and largest professional organization dedicated to advancing cancer research. The membership includes more than 28,000 basic, translational and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and nearly 90 other countries. The AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants. The AACR Annual Meeting attracts more than 17,000 participants who share the latest discoveries and developments in the field. Special conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment and patient care. The AACR publishes six major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; Cancer Epidemiology, Biomarkers & Prevention; and Cancer Prevention Research. The AACR also publishes CR, a magazine for cancer survivors and their families, patient advocates, physicians and scientists. CR provides a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship and advocacy.
The project described was supported by Grant Number T32HD046377 from the National Institute of Child Health and Human Development and its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institute of Child Health and Human Development.