Good news on the front-line of cancer research. Rates of new diagnoses and rates of death from all cancers combined declined significantly in the most recent time period for men and women overall and for most racial and ethnic populations in the United States, according to a report from leading health and cancer organizations. The drops are driven largely by declines in rates of new cases and rates of death for the three most common cancers in men (lung, prostate, and colorectal cancers) and for two of the three leading cancers in women (breast and colorectal cancer). New diagnoses for all types of cancer combined in the United States decreased, on average, almost 1 percent per year from 1999 to 2006. Cancer deaths decreased 1.6 percent per year from 2001 to 2006.
These findings are from a report authored by researchers from the National Cancer Institute (NCI), part of the National Institutes of Health, the Centers for Disease Control and Prevention (CDC), the American Cancer Society (ACS), and the North American Association of Central Cancer Registries (NAACCR). The report was published early online Dec. 7, 2009, in the journal Cancer.
Overall cancer rates continue to be higher for men than for women, but men experienced the greatest declines in incidence (new cases) and mortality (death) rates. For colorectal cancer, the third most frequently diagnosed cancer in both men and women, and the second leading cause of cancer deaths in the United States, overall rates are declining, but increasing incidence in men and women under 50 years of age is of concern, the report said.
In the Special Feature section, the authors used modeling projections of colorectal cancer rates to find that, with accelerated cancer control efforts to get more Americans to adopt more favorable health behaviors (such as quitting smoking) and higher use of screening (such as colonoscopy), as well as optimal treatment outcomes for colorectal cancer (such as more effective chemotherapy), there could be an overall colorectal cancer mortality reduction of 50 percent by 2020.
Other highlights from the report show that in men, incidence rates have declined for cancers of the prostate, lung, oral cavity, stomach, brain, colon and rectum, but continue to rise for kidney/renal, liver, and esophageal cancer, as well as for leukemia, myeloma and melanoma. In women, incidence rates decreased for breast, colorectal, uterine, ovarian, cervical and oral cavity cancers, but increased for lung, thyroid, pancreatic, bladder, and kidney cancers, as well as for non-Hodgkin lymphoma, melanoma and leukemia.
“The continued decline in overall cancer rates documents the success we have had with our aggressive efforts to reduce risk in large populations, to provide for early detection, and to develop new therapies that have been successfully applied in this past decade,” said NCI Director John E. Niederhuber, M.D. “Yet we cannot be content with this steady reduction in incidence and mortality. We must, in fact, accelerate our efforts to get individualized diagnoses and treatments to all Americans and our belief is that our research efforts and our vision are moving us rapidly in that direction.”
Among racial/ethnic groups, cancer death rates were highest in black men and women and lowest in Asian/Pacific Islander men and women. Although trends in death rates by race/ ethnicity were similar for most cancer sites, death rates from pancreatic cancer, the fourth most common cause of cancer death in the United States, increased among white men and women but decreased among black men and women.
The three leading causes of cancer death for all men, with the exception of Asian/Pacific Islanders, were lung, prostate and colorectal cancer. Lung, liver and colorectal cancers were the top three causes of cancer death in Asian/Pacific Islander men. For women, the three leading causes of cancer death were lung, breast and colorectal cancer for all racial/ethnic groups except Hispanic women, for whom breast cancer ranked first. 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.
“The continued decline in incidence and death rates for all cancers combined is extremely encouraging, but progress has been more limited for certain types of cancer, including many cancers that are currently less amenable to screening, such as cancer of esophagus, liver and pancreas,” said Betsy Kohler, executive director of NAACCR.
The special section on colorectal cancer rates says that long-term incidence trends for colorectal cancer have been fairly consistent for men and women, with major declines from 1985 to1995, minor increases from 1995 to1998, and significant declines from 1998 to 2006. Since 1984, death rates have also declined for men and women with accelerated rates of decline since 2002 for men and 2001 for women. In the most recent decade for which there are data (1997-2006), rates of newly diagnosed colorectal cancer have decreased for men and women in all racial/ethnic groups examined except American Indian/Alaskan Native (AI/AN) women. Incidence rates declined most rapidly among men and women over 65 years of age and increased most rapidly in people under age 50 in most population groups.
“This report shows that we have begun to make progress reducing colorectal cancer. Yet, colorectal cancer still kills more people than any other cancer except lung cancer,” said CDC Director Thomas Frieden, M.D. “Reducing smoking further can bring lung and other cancer rates down, and improved colorectal cancer screening can prevent colorectal cancer. Through CDC’s Colorectal Cancer Control Program, we have tremendous potential to reduce the disparities that exist in colorectal cancer screening and to save lives.” The CDC program supports population-based screening efforts and provides colorectal cancer screening services to low-income men and women ages 50 to 64 years who are underinsured or uninsured for screening, when no other insurance is available.
Researchers used microsimulation modeling to analyze the historical impact of changes in risk factors, screening and treatment practices, and to project future mortality trends for colorectal cancer. The model, named MISCAN-Colon, which was developed by NCI’s Cancer Intervention and Surveillance Modeling Network (CISNET) consortium, simulates the U.S. population from 1975 through 2020. The model includes factors that could increase risk for colorectal cancer (i.e., smoking, obesity, and red meat consumption), as well as factors that could decrease colorectal cancer risk (i.e., aspirin use, consumption of supplements such as folate and calcium, and physical activity). To calculate screening use, researchers used national data on the use of fecal occult blood testing (which looks for blood in stool samples), and endoscopy (including flexible sigmoidoscopy and colonoscopy, which allows doctors to examine the lower part of the colon or the entire large intestine, respectively). To assess the effects of treatment, researchers assessed data on use of, and disease-free survival rates associated with, four chemotherapy regimens used for advanced colorectal cancer during different historical time periods.
Using the model, the researchers were able to estimate the impact of historical changes in risk factors, screening practices, and treatment advances on past changes in incidence and mortality, as well as predict future trends through 2020.
From 1975 to 2000, colorectal cancer incidence fell 22 percent, half of which was most likely due to changes in risk factors, and half due to screening. Similarly, colorectal cancer deaths fell by 26 percent during that time period, with a 9 percent drop resulting from a change in risk factors, a 14 percent drop from screening, and a 3 percent drop from improved treatment.
The researchers created projections to look at how colorectal cancer mortality trends could change with varying levels of cancer control interventions. If there were no changes in risk factors, screening or treatment (stable since 2000), Americans could expect a 17 percent decline in colorectal cancer mortality from 2000 to 2020. However, if current trends persist, Americans could see a 36 percent decline in colorectal cancer mortality. With accelerated cancer control efforts, there could be an overall colorectal cancer mortality reduction of 50 percent by 2020.
“The extraordinary progress on colorectal cancer shows what can be achieved by coordinated and targeted efforts to apply existing knowledge to cancer control at the state and federal level,” said John R. Seffrin, Ph.D., chief executive officer of the American Cancer Society. “Increases in colorectal cancer screening have been achieved through a variety of efforts, including education of the public and medical community and advocacy for health insurance coverage of the full range of colorectal cancer screening tests. The American Cancer Society is committed to continuing these efforts to get as close as we can to the potential 50 percent colorectal cancer mortality reduction that this report says is possible.”