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The cancer death rate in the United States -- which has been slowly dropping since 1993 -- has fallen even more significantly in recent years, according to an annual report from the nation's leading cancer organizations.

Previous studies had shown cancer death rates in the US decreasing by an average of 1.1% a year from 1993 through 2002, a steady decline credited to the effectiveness of prevention efforts, new screening methods and wider use of early detection, and better treatments that have extended life expectancy after diagnosis. Those benefits appear to be accumulating more rapidly, with the latest report showing evidence that the decline in cancer deaths nearly doubled from 2002 through 2004, with an average decrease of 2.1% seen each year. Because death rates are considered the best indicator of progress against cancer, this encouraging trend gets top billing in the Annual Report to the Nation on the Status of Cancer, 1975-2004, Featuring Cancer in American Indians and Alaska Natives.

The report will be published online October 15, 2007, and will appear in the November 15, 2007, issue of Cancer. It is a collaborative effort of the American Cancer Society, the National Cancer Institute, the Centers for Disease Control and Prevention, and the North American Association of Central Cancer Registries. For this year's report, which takes an in-depth look at cancer among American Indians and Alaska Natives, researchers from the Indian Health Service, the Mayo Clinic College of Medicine, and the New Mexico Tumor Registry also participated as co-authors.

Looking at the population as a whole, the report shows that cancer death rates have decreased for the majority of the 15 most commonly diagnosed cancers in men and women. This includes important declines in the 3 leading causes of cancer deaths in men -- lung, prostate, and colorectal cancers -- and in 2 of the 3 leading causes of cancer deaths in women -- colorectal cancer and breast cancer. Death rates from lung cancer, the number one cause of cancer death in both sexes, continued to increase in women, but at a substantially slower rate than in years past.

"The evidence is unmistakable: We are truly turning the tide in the cancer battle," said John R. Seffrin, PhD, chief executive officer of the American Cancer Society. "The gains could be even greater if everyone in the US had access to essential health care, including primary care and prevention services."

In addition to cancer death rates, researchers also crunched the numbers for cancer incidence rates, or the rate at which new cancers are diagnosed. Overall, things look good: Cancer incidence rates for all cancer sites, both sexes, and all races combined declined slightly from 1992 through 2004.

The drop in breast cancer incidence was especially striking. Between 2001 and 2004, breast cancer rates in women went down by 3.4% per year. Some of that decline was due to less use of hormone therapy (which may also account for a drop in ovarian cancer rates). But some may be partly due to the fact that mammography rates have also gone down. If fewer women are getting screened, it may be that we're simply not finding as many cancers early, even though they're still developing.

On the other hand, increased screening could be connected to an increase in incidence because more cancers are being found before they cause symptoms. That's what researchers think caused a jump in prostate cancer rates between 1988 and 1992.

Among the caveats and clarifications to consider in the latest statistics on cancer incidence:

• For men, incidence rates for all cancers decreased by 4.3% per year from 1992 through 1995 and were stable from 1995 through 2004. But incidence rates of myeloma and cancers of the liver, kidney, and esophagus continued to increase for men through 2004.
  
  
• For women, incidence rates for all cancers combined stabilized from 1999 through 2004 after years of increases. Still, the rates for non-Hodgkin lymphoma, melanoma, leukemia, and cancers of the bladder and kidney have been increasing for 29 years. Thyroid cancer incidence rates in women have been going up since 1980.
  
  
• Lung cancer incidence rates in women stabilized from 1998 through 2004 following a period of long-term increase. In this case, incidence rates lag behind smoking patterns by several years. Smoking became more common among US women in the years after World War II, leading to higher lung cancer rates down the line. As anti-tobacco efforts have led to lower smoking rates, the increase in lung cancer incidence rates is leveling off.
  
  
• Lung cancer incidence rates in men declined 1.8% per year from the period 1991 through 2004.
  
  
• Colorectal cancer incidence rates decreased by more than 2.0% per year for men and women, likely due to prevention through the removal of precancerous polyps.

A special section in this year's Report to the Nation provides the most comprehensive cancer data to date for American Indians and Alaska Natives (AI/AN), one of the fastest growing populations in the US. The authors looked at cancer patterns as they apply to AI/AN residents of 6 specific geographic regions: Alaska, Pacific Coast, Northern Plains, Southern Plains, Southwest, and East. These patterns were compared to similar statistics for non-Hispanic white residents of the same region.

Because the AI/AN population is younger on average than the non-Hispanic white population, the authors age-adjusted their findings for the sake of comparison. In doing so, they found higher overall cancer incidence rates for AI/AN people in Alaska and the Northern and Southern Plains regions. The incidence of cancer was lower in the Southwest.

They also reported on socioeconomic indicators that might relate to cancer risk. For instance, they found that American Indians and Alaska Natives were more likely to live in poverty and less likely to have a high school education and health coverage than non-Hispanic whites. Commonly, poverty, low education, and lack of insurance are indicators of less access to cancer prevention and control services.

In general, smoking rates are high among AI/AN, especially in Alaska and the Northern Plains. In all regions, a greater percentage of AI/AN were obese, compared to the white population, and screening rates were lower for breast, colorectal, prostate, and cervical cancers.

While the 3 most common cancers for AI/AN men and women are the same as for white men and women, important differences by region and type of cancer were observed, including:

• For all cancers combined, rates of cancer incidence were lower for AI/AN in the Southwest and higher in the Plains and Alaska.
  
  
• Lung and colorectal cancer incidence rates for AI/AN -- both men and women -- were highest in the Northern Plains and Alaska and were significantly higher than rates in white people.
  
  
• From 1999 to 2004, new diagnoses for cancers of the kidney, stomach, liver, cervix, and gallbladder were higher in AI/AN than in white populations. This was true in all regions studied.
  
  
• With the exception of Alaska, AI/AN persons were less likely than whites to be diagnosed with early stages of colorectal cancer, with the difference being larger in the Southwest, Northern Plains, and Southern Plains regions.
  
  
• AI/AN women in all regions of the US were less likely than white women to be diagnosed with localized breast or cervical cancer.

"We are firmly committed to addressing cancer health disparities so that the benefits of decades of research can reach all Americans," said National Cancer Institute Director John E. Niederhuber, MD. "The fact that lung and colorectal cancers rates were higher in some American Indian and Alaska Native populations points to the work we still have to do."

Citation: "Annual Report to the Nation on the Status of Cancer, 1975-2004, Featuring Cancer in American Indians and Alaska Natives." Published online Oct. 15, 2007, in Cancer. First author: David K. Espey, MD, Centers for Disease Control and Prevention.