Cancer mortality rates fall to an all-time low
■ But not for all cancers, and trend lines for some health-related behaviors are heading in the wrong direction.
By Victoria Stagg Elliott — Posted Jan. 23, 2006
The cancer death rate has struck a new low, continuing the trend it began in 1992. Additionally, patterns for some lifestyle choices that contribute to the development of the disease have maintained a downward spiral, while screening for certain cancers has increased, according to the "Cancer Trends Progress Report -- 2005 Update," issued by the National Cancer Institute last month.
"The mortality rate is declining, and that is the most important and simple measure of the progress against cancer," said Robert Croyle, PhD, a member of the report's external advisory group and director of the NCI's Division of Cancer Control and Population Sciences. "The most important factor is the decline in tobacco use."
Encouraging signs in this regard continue. The percentage of high-school students who identified themselves as regular smokers plummeted from a high of just over 37% in 1999 to just shy of 22% in 2003. Meanwhile, in regard to other prevention efforts, slightly more than 60% of people took steps to protect their skin from cancer in 2002 compared with 53% in 1992. On the screening front, nearly 70% of women older than 40 in 2003 had received a mammogram in the past two years. In 1987, that figure was only 27%.
"We are making remarkable progress," said Tim Byers, MD, MPH, deputy director of the University of Colorado Cancer Center in Denver. "And I'm very optimistic about the future as well."
In part, the positive changes in cancer mortality rates can be attributed to improvements in treatment. Examples of recent progress, for instance, are chronicled in "Clinical Cancer Advances 2005," a report issued by the American Society of Clinical Oncology last month. But despite this kind of good news, the NCI report includes other findings -- especially regarding the utilization of cancer prevention strategies and screening -- that still cause concern.
"It's very important to have new drugs and new treatments, but what we should be doing is preventing cancer and making sure people get the right screening tests," said Robert J. Mayer, MD, professor of medicine at the Dana-Farber Cancer Institute in Boston and a past president of ASCO. "Making me see fewer patients would be fine with me."
Room for improvement
In the area of screening, the early detection of breast and cervical cancer has made significant inroads, but the same cannot be said for colon cancer. According to the NCI report, only 55% of people older than 50 had any colorectal cancer screening at all in 2000, far lower than the rates of screening for other cancers where such testing is possible.
Several medical societies have programs to raise awareness of colon cancer screening guidelines, and experts say this is an effort that requires attention.
"It's disappointing that the rates are so low, considering how effective it is," Dr. Croyle said. "More significant effort is needed to promote screening."
Concerns also persist that even tests that are more widely used may not always be accessible. The NCI report found that mammography rates were lower for Hispanics than for Caucasians and African-Americans. Also, a study in the January Journal of Clinical Oncology found that rates were not much higher among women who had already had breast cancer for whom regular mammography in the years after treatment is more strongly recommended. In the study, about 77% of women who had survived cancer had a mammogram one year after treatment. The number who had annual screening three years afterwards dipped to nearly 57%.
"We felt that the numbers were lower than they probably should be," said Nancy Keating, MD, MPH, lead author on that paper and assistant professor of medicine at Brigham and Women's Hospital and Harvard Medical School in Boston. "Women from age 50 to age 70 should be getting annual mammograms, and if you have had cancer, you certainly should be getting them."
There are also concerns that improvements in some lifestyle factors eventually may be outweighed by the worsening of others. Smoking and alcohol consumption has decreased, meaning that some of the cancers linked to these behaviors have gone down. Fewer people, however, are maintaining a healthy weight, eating a healthy diet or being physically active.
"I'm very concerned about the increase in the obesity rates and the impact that this will have on cancer incidence when we're finally having some benefit from all the efforts over the last century against tobacco," Dr. Croyle said.
In 1972, nearly half of Americans maintained a healthy weight. Now, less than a third do. This circumstance is believed to be a significant contributor to the increases in esophageal and kidney cancer, which are two of a handful of carcinomas that are on the rise.
But while this is generating worry and effort from public health officials and medical societies such as the American Medical Association, it is also viewed as a far more challenging issue than tackling the other vices.
"It's much, much harder to combat obesity from a clinician's as well as a patient's standpoint. And once you reach a certain weight, it's very difficult," said Diane Harper, MD, MPH, associate professor of obstetrics-gynecology and community and family medicine at Dartmouth Medical School in Hanover, N.H.
It also appears that pharmacologic preventives may not be imminent. Two studies published this month suggested that statins may not have any impact on cancer risk. One in the Journal of the National Cancer Institute authored by American Cancer Society researchers found no impact of cholesterol-lowering drugs on colon cancer.
Another study, a meta-analysis by researchers from the University of Connecticut School of Pharmacy published in the Journal of the American Medical Association, determined that statins made no difference to overall cancer incidence or mortality.
"We could find no type of cancer that statins benefited," wrote the authors of the JAMA paper.