Overall Cancer Mortality Declining at Record Pace, Says National Study

Cancer mortality rates in the United States are dropping more quickly now than ever, and most cancer incidence rates also are declining.

That's the news from "Annual Report to the Nation on the Status of Cancer, 1975-2004, Featuring Cancer in American Indians and Alaska Natives," which is scheduled to appear in the Nov. 15 print issue of Cancer. The report, which is jointly produced each year by the American Cancer Society, the CDC, the National Cancer Institute and the North American Association of Central Cancer Registries, was published online (34-page PDF; About PDFs) Oct. 15.

The report finds that the overall rate of decline in cancer deaths per year nearly doubled from 2002 through 2004 compared with 1993 through 2002; during 2002 through 2004, the average rate of decrease was 2.1 percent each year, compared with 1.1 percent per year for 1993 through 2002. The three leading causes of cancer deaths in men -- lung, prostate and colorectal cancers -- have all shown declining rates. For women, two of the three leading causes of cancer deaths -- colorectal and breast cancers -- have seen declining rates. The rates of death from lung cancer, the third leading cause of cancer deaths in women, continued to increase, but at a slower pace than in years past.

In addition, cancer incidence rates for all cancers in both sexes and all ethnicities combined declined slightly from 1992 through 2004, according to the study. There was a marked decline in breast cancer incidence (see sidebar); from 2001 through 2004, breast cancer rates in women went down by 3.5 percent per year. The study researchers speculate that this decline may be due to women's decreased use of hormone replacement therapy or tied to the fact that mammography rates also have gone down during the past several years, in which case, they note, "A decrease in breast cancer incidence attributable to lower mammography use would represent an artifact of underdiagnosis or delayed diagnosis and not a true decrease in the rate of invasive breast cancer."

Inversely, the researchers attribute a jump in prostate incidence rates among men to increased screening rates for that disease.

Lung cancer incidence rates in men continued their long-standing downward trend, but remained stable in women. And for both men and women, colorectal cancer incidence and mortality rates decreased, which the researchers note, was likely associated with increased prevention through removal of precancerous polyps, improving cancer outcomes by earlier stage diagnosis, reducing exposure to risk factors and improving cancer treatment.

However, incidence rates of myeloma and cancers of the liver, kidney and esophagus increased for men through 2004. In women, the rates of non-Hodgkin's lymphoma, melanoma, leukemia and cancers of the bladder and kidney have been increasing for nearly three decades. The incidence rates of thyroid cancer in women have been increasing since 1980, with the rate of increase nearly tripling from 1995 through 2004.

A new section of the annual report provides cancer data for American Indians and Alaska Natives, or AI/AN, categorized by geographic region. Researchers found higher overall cancer incidence rates for AI/AN people in Alaska and the Northern and Southern Plains regions. The overall incidence of cancer was lowest in the Southwest. They also found that AI/AN people were more likely to live in poverty and less likely to have a high-school education or health coverage than non-Hispanic whites. Compared with non-Hispanic whites, the proportion of individuals age 18 to 64 with no usual source of health care was higher among AI/AN populations overall and in all regions.

Lung and colorectal cancer incidence rates for AI/AN men were highest in the Northern Plains and Alaska and were significantly higher than the rates in non-Hispanic whites. In the Northern Plains, the incidence rate of lung cancer among AI/AN women was nearly double that seen in non-Hispanic white women; the rate among AI/AN women in the Southwest, however, was only one-fifth that seen in non-Hispanic white women. The colorectal cancer incidence rate among AI/AN women was highest in Alaska.

Overall, AI/AN individuals were less likely than non-Hispanic whites to be diagnosed with early-stage colorectal cancer. And AI/AN women in all regions were less likely than white women to be diagnosed with localized breast or cervical cancer.