WASHINGTON--For the first time since 1973, when the government began tracking cancer rates, epidemiologists have documented a significant drop in overall cancer incidence in the United States. They also found that mortality rates for all cancers combined continued to drop in 1995.
The newest analysis of national trends shows that cancer incidence overall declined an average of 0.7% per year between 1990 and 1995. The biggest drop was seen after 1992, when cancer incidence peaked at 426 per 100,000 Americans. In 1995, the number had decreased to 392 per 100,000.
The death rate for all cancers combined fell 0.5% per year during the same period, continuing a trend in mortality data first reported in November 1996. Preliminary data indicate that "the trends for 1996 appear to continue," Edward Sondik, PhD, director of the National Centers for Health Statistics (NCHS), said at a press conference.
The decrease in incidence followed a 1.2% per year increase from 1973 to 1990, a period when the rise in cancer mortality was 0.4% a year. Looking at estimates made 8 to 10 years ago, the new mortality figures represent "a 1% drop in mortality rates compared to the projected rise, if nothing had changed," said Richard D. Klausner, MD, director of the National Cancer Institute. As a result, "there were 25,000 to 30,000 fewer deaths in 1995 than we would have expected, and over 70,000 fewer cases of cancer."
John R. Seffrin, PhD, chief executive officer of the American Cancer Society, attributed the turn-around in incidence and mortality to prevention measures (particularly the reduction in smoking), early screening and better diagnostics, improved therapies, education efforts aimed at health care professionals, and a broader array of cancer control measures at the community level.
"We are witnessing an unprecedented downturn in both new cancer cases and in cancer death rates," Dr. Seffrin said. He pointed out that the United States has spent some $30 billion on cancer research since President Nixons 1971 declaration of war on cancer, and the new data show that the "investment in research is paying off."
The new analysis used incidence data from NCIs Surveillance, Epidemiology and End Results (SEER) Program and mortality figures from the NCHS, a part of the Centers for Disease Control and Prevention (CDC).
The study, by Phyllis A. Wingo, PhD, of the ACS; Lynn A.G. Ries, MS, and Brenda K. Edwards, PhD, of NCI; Harry M. Rosenberg, PhD, of NCHS; and Daniel S. Miller, MD, of CDCs National Center for Chronic Disease Prevention and Health Promotion, appears in the March 15, 1998, issue of the journal Cancer.
The researchers compared age-adjusted data from two time periods, 1973 to 1990 and 1990 to 1995. Their report provides incidence and mortality data for whites, blacks, Asians and Pacific Islanders, and Hispanics for the 23 leading cancers. Although overall the numbers proved encouraging, the decline in new cancer cases and cancer deaths was neither uniform nor observed in all cancers in the four population groups.
"Incidence rates declined in most age groups for both men and women and for most racial and ethnic groups," Dr. Sondik said. "Exceptions were black males, whose rates continued to increase--in fact, black males have the highest cancer rate of any group in the country--and Asian and Pacific Islander women, whose cancer incidence rates remained essentially stable."
Said James S. Marks, MD, director of the National Center for Chronic Disease Prevention and Health Promotion: "We realize that the declines in cancer incidence and deaths have not been seen for all Americans and that our collective efforts must be directed at reaching populations with a disproportionate cancer burden."
The drop in mortality was greater for the population under age 65 than over age 65, and men experienced a larger decline in cancer deaths than women, Dr. Sondik said. For the four specific populations, the overall cancer death rate was down for all groups except for the Asian and Pacific Islander females, whose death rates increased.
During the 1990s, the four most common cancer sites, accounting for 54% of newly diagnosed cancers, were the lung and bronchus, prostate, female breast, and colon and rectum. Examination of cancer death rates for each site by sex, race, and ethnicity revealed that, except for female lung cancer, blacks had higher cancer death rates than whites, Asians and Pacific Islanders, or Hispanics.
Four Major Cancer Sites
Dr. Sondik said that these four sites "illustrate the overall trends and at the same time underscore the differences in cancer experiences for different groups."
- Lung. For women, the study found, the rate of both new lung cancer cases and deaths continued to rise in the 1990s, while both incidence and mortality rates declined in men.
"The increase in lung cancer for women accounts for much of the reason that men have experienced a greater decline in overall cancer rates than women," Dr. Sondik said. Men in all four ethnic and racial groups had a decline in lung cancer incidence, he noted, "but in women, only Hispanic women, to a notable extent, and black women, to a lesser degree, showed a decline in the incidence of new cases. Hispanic women had the only drop in lung cancer mortality among women."
- Breast. After a steady rise through the 1970s and 1980s, breast cancer incidence leveled off during the 1990s. Mortality had also been on the rise, Dr. Sondik said, but declined over the past 5 years, although only in white and Hispanic women. Breast cancer death rates remain stable for black women, and may be on the rise for Asian and Pacific Islander women, he said.
- Prostate. The incidence of prostate cancer has dropped in white men since 1990 and in black men since 1993, although blacks continue to have rates much higher than the other groups. Death rates are also dropping, except for Hispanic men.
- Colorectal. Both incidence and mortality have declined since 1990 for both men and women, except for an increase in mortality among Asian and Pacific Islander women.
"Indeed, for many of the other top cancer sites, incidence and mortality declined over this period after almost 20 years of increasing rates," Dr. Sondik said. But not all. For example, both incidence and mortality from non-Hodgkins lymphoma have continued to increase.
New cases of melanoma skin cancer are on the rise, but mortality shows a slight decline. Also, surprisingly, Dr. Sondik said, "the incidence of uterine cancer actually reversed its decline from 1973 to 1990 and is now increasing--yet at the same time, its death rate has declined."