Report to Nation Finds Continued Declines in Many Cancer Rates
Report to Nation Finds Continued Declines in Many Cancer Rates
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The drop in cancer death rates continues a trend that began in the early 1990s. The report finds, for the first time, lung cancer death rates decreased in women, more than a decade after rates began dropping in men.
The report is co-authored by researchers from the North American Association of Central Cancer Registries (NAACCR), the National Cancer Institute (NCI), part of the National Institutes of Health, the Centers for Disease Control and Prevention, and the American Cancer Society. It appeared online March 31, 2011, in the Journal of the National Cancer Institute, and in print on May 4, 2011.
Of special note, childhood cancer incidence rates (rates of new diagnoses) continued to increase while death rates in this age group decreased. Childhood cancer is classified as cancers occurring in those 19 years of age or younger.
Overall cancer incidence rates in men were essentially unchanged. There was a very small uptick in prostate cancer rates, and if these rates were excluded from the analysis, there would be a continued decline in overall male incidence rates.
In the Special Feature section of the report, the authors explore the diversity of brain tumors and other nervous system cancers beyond those that are identified as malignant, including those that are borderline and benign. The researchers analyzed data between 2004 and 2007 and found that in adults, non-malignant tumors were about twice as common as malignant tumors.
“Our new data show that non-malignant brain tumors are far more common than malignant brain tumors, and affect different population groups. Brain tumors have a far-reaching effect on our families and friends, yet they are difficult to study due to their diversity,” said Betsy Kohler, executive director, NAACCR. “We hope that the collection of both malignant and non-malignant brain tumors by central cancer registries will continue to provide a significant source of information and insight to researchers.”
Other highlights from the report show that, in men, incidence rates have declined for cancers of the lung, colon and rectum, oral cavity and pharynx, stomach, and brain (malignant only) while rates have risen for kidney, pancreas and liver cancers, as well as melanoma of the skin. In women, incidence rates decreased for breast, lung, colorectal, uterine, cervical, bladder, and oral cavity cancers, but increased for kidney, pancreas, and thyroid cancers as well as for leukemia and melanomas of the skin.
"It is gratifying to see the continued steady decline in overall cancer incidence and death rates in the United States — the result of improved methods for preventing, detecting, and treating several types of cancer," said Harold Varmus, M.D., NCI director. "But the full repertoire of numbers reported today also reflects the enormous complexity of cancer, with different trends for different kinds of cancers, important differences among our diverse people, and different capabilities to prevent, detect, and treat various cancers. Moreover, as our population continues to age, we have an obligation to discover and deliver better ways to control all types of cancers."
Among racial/ethnic groups, cancer death rates were highest among black men and black women, but this group also showed the largest decline for the period between 1998 and 2007 compared with other racial groups. For new cancers, black men had the highest incidence rates in the 2003 to 2007 period studied. Among women, white women had the highest overall incidence rates. Breast cancer was the most commonly diagnosed cancer among women regardless of race or ethnicity. The differences and fluctuations in death rates by racial/ethnic group, sex, and cancer site may reflect differences in risk behaviors, socioeconomic status, and access to and use of screening and treatment.
“As we work towards reducing the cancer burden in the population as a whole, it is important that we apply what we know about prevention, detection and treatment of cancer to populations at highest risk,” said John R. Seffrin, Ph.D., chief executive officer of the American Cancer Society. “While it's promising that mortality gaps are closing for some racial/ethnic groups, continued efforts are needed to prevent the avoidable deaths that these gaps represent.”
Despite the drop in lung cancer deaths among women nationwide, lung cancer still kills more people than any other type of cancer. “Lung cancer can become a rare disease if states support well-funded tobacco control programs,” said CDC Director Thomas Frieden, M.D. “Aggressive ad campaigns that show the impact of smoking, combined with higher cigarette prices and strong state laws that protect nonsmokers from secondhand smoke, will decrease the number of adult smokers and save lives."
In the Special Feature section, the authors note that non-malignant tumors make up two-thirds of all adult brain tumors and one-third of childhood brain tumors, with meningiomas being the most common type of brain and other nervous system tumor in the U.S. Changes in diagnostic techniques, including the introduction of computed tomography, or CT, scans in the 1970s and magnetic resonance imaging, or MRI, in the 1980s, have led to less invasive methods for diagnosing brain tumors, but also have had a strong influence on incidence rates over the past decades. Newer molecular studies have improved classification of brain tumors for treatment and prognostic purposes.
Of note in the discussion of trends in malignant brain tumor incidence is the relative stability of long-term trends for tumors of neuroepithelial tissue, which arise from glial (support) cells in the brain and other tissues. Incidence rates for glioblastoma, the most common, as well as highly fatal, form of these malignant tumors, increased from 1980 through 1991, likely due to increasing use of aggressive diagnostic procedures in elderly patients, but since 1991 the rates have been stable. The report notes that the relatively low variation in incidence and mortality rates over the past several decades for brain cancers suggest that external risk factors in the environment do not play a major roles in this disease.