Drop in mortality rates continues for most common cancers
■ But a new report also finds significant cancer rates among American Indians and Alaska Natives, in contrast to earlier beliefs.
By Susan J. Landers — Posted Nov. 12, 2007
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Washington -- Declining death rates from some of the most common cancers contributed to an overall drop in the disease's mortality, a trend that has picked up speed in recent years, according to a new report by the nation's leading cancer organizations.
Cancer deaths dropped 2.1% per year on average from 2002 to 2004, nearly twice the annual decrease of 1.1% per year that occurred from 1993 through 2002.
These measures were published in the "Annual Report to the Nation on the Status of Cancer, 1975-2004."A joint project of the Centers for Disease Control and Prevention, the American Cancer Society, the National Cancer Institute and the North American Assn. of Central Cancer Registries, the report was published online Oct. 15 and will appear in the Nov. 15 print edition of Cancer.
The recent downturn was driven by lower death rates for many of the most common cancers, including breast cancer in women, lung and prostate cancer in men, and colorectal cancer in men and women.
Deaths among men declined by 2.6% per year from 2002 to 2004 and by 1.8% per year for women, according to the report.
"The decline represents a convergence of a lot of factors," said Brenda Edwards, PhD, director of the NCI's Surveillance Epidemiology and End Results, or SEER, program, from which much of the report's data were drawn.
She cited improved tobacco-control policies and screening programs as well as improved treatments. "You have to orchestrate a lot of different interventions over many years to generate this type of mortality benefit," Dr. Edwards said. "It's strong, evidence-based cancer control science, and it's paying off."
Louis Weiner, MD, chair of the Dept. of Medical Oncology at Fox Chase Cancer Center in Philadelphia, applauded the news. As a colorectal cancer specialist, he had seen survival times increasing for his patients. "My clinics are stuffed to the gills because people are living longer than they used to," he said. "That is the most pleasant kind of problem we ever could have."
Although colonoscopies are detecting colorectal cancers at earlier and more curable stages, those are not the patients Dr. Weiner is seeing. "What I'm seeing are people who have more advanced cancers but for whom there are more effective drugs than before. As a consequence, they are flat-out surviving longer."
Drop in rate depends on type
Different factors can help explain the declining rates depending on the type of cancer, Dr. Weiner suggested. For breast cancer, early detection, established therapies and the routinization of therapies that are applied rigorously have made a difference. For lung cancer, prevention through smoking cessation should be emphasized.
"For colorectal cancer, my instinct is that the availability of better drug treatments has been the primary driver of the improvements," Dr. Weiner said.
But not all of the news was good. The report also found increases in death rates for esophageal and liver cancers in men, and more deaths from cancers of the liver and lungs among women.
Cancer incidence rates for men and women of all races demonstrated an overall slight decline from 1992 through 2004, the report said -- the first such decline in 20 years. The sharpest drop occurred with breast cancer from 2001 through 2004. There were 3.5% fewer cases diagnosed each year.
The report's authors cited ongoing speculation on whether the precipitous drop in the use of hormone replacement therapy in postmenopausal women could be responsible or whether a recent decline in the rate of screening mammography meant the cancers are still present, just not yet detected.
The authors also noted that there had been a 3.3% decline in the incidence of ovarian cancer from 2001 through 2004, and they suggest that the sharp decline in hormone use also could be responsible for this drop. Hormone use is a risk factor for ovarian as well as breast cancer, noted Len Lichtenfeld, MD, deputy chief medical officer at the American Cancer Society, who presented the highlights of the report on his cancer society blog.
Women's lung cancer stable
The incidence of lung cancer among women also has stabilized, according to the report. This finding is related to historical patterns of smoking, said Elizabeth Ward, PhD, director of surveillance research at the cancer society. The smoking prevalence in U.S. women declined from 33.9% in 1965 to 19.2% in 2003.
The report contains a special section on cancer trends among American Indians and Alaska Natives, which are among the fastest-growing populations in the nation. "This is the first time we really have good data on the number of cancer cases among this population," said Judith S. Kaur, MD, director of Native American Programs at the Mayo Clinic Comprehensive Cancer Center in Rochester, Minn. Dr. Kaur was also an author of the report.
Data collected in earlier years had suggested that cancer was not a problem among American Indians, she said. But that information was "absolutely wrong."
The report found that incidence rates for rarer cancers such as liver and gallbladder cancer are higher among American Indians and Alaska Natives, and common cancers such as lung, colorectal and breast are becoming more common. There also are geographic differences that could help guide screening and research efforts.