Cancer death rates continued to fall in the US during the years 1993 through 1999, according to a consensus report by five government and private health organizations.

The "Annual Report to the Nation on the Status of Cancer, 1973-1999, Featuring Implications of Age and Aging on the US Cancer Burden" will be published in the May 15 issue of the journal Cancer (Vol. 94, No. 10: 2766-2792). The initial "Report to the Nation" was issued four years ago and documented the first sustained decline in cancer death rates.

"The good news in this report is the continuing fall in cancer death rates by slightly more than one percent per year between 1993 and 1999," said John R. Seffrin, PhD, chief executive officer of the American Cancer Society (ACS).

But the actual numbers of cancer cases and deaths were up, because the percentage of Americans developing cancer every year is holding steady while the US population is growing larger. More people are living into the age ranges where cancer is more common, said experts.

If those trends continue, by the year 2050 there could be twice as many people diagnosed with cancer each year. Much of this will be because of an almost three-fold increase in the number of people older than 75 who will be diagnosed with cancer for the first time.

"The total impact of cancer on the US population is a combination of how all those trends affect us," said the report's lead author, Brenda K. Edwards, PhD, associate director for surveillance research programs at the National Cancer Institute (NCI).

The report was the fifth yearly "report card" to the nation. This year it was compiled by the ACS, the NCI, the North American Association of Central Cancer Registries, the Centers for Disease Control and Prevention, and the National Institute on Aging.

Most of the decline in death rates occurred among the four major cancer killers — lung, colorectal, breast and prostate — that together account for more than half of all US cancer deaths.

Lung cancer death rates were down among all age and sex groups except older women.

"The group of women who had the longest exposure to tobacco use is aging so their lung cancer rates are going up, and younger women have smoked less, and their rates are lower, so it is quite related to use of tobacco," noted Edwards.

Men took up smoking earlier but more of them quit earlier, the report noted.

Edwards said some experts believe wider use of colorectal cancer screening tests could be a reason colorectal cancer death rates fell. Improvements in surgical techniques and related support efforts, and improvements in diet and lifestyle among some, may have helped lower these rates as well, she said.

Breast cancer death rates had been declining among white women for some time, and are now dropping among black women for the first time. This drop may have occurred because more black women are now taking advantage of ways to find breast cancer early. As a result, these women are often being treated in early stages of the disease.

Prostate cancer death rates fell as well. Most experts think the PSA test has helped find more prostate cancers early, but it's not yet clear whether that or better treatments (or both) have driven prostate cancer death rates lower, said Edwards.

Men's chances of developing any kind of cancer fell, but women's rose, with the largest increase in breast cancer.

Most of the increase in new breast cancer cases was early stage breast cancer most often found through early detection by breast self exam (BSE), clinical breast exam, or mammography, said Edwards.

Finding the disease in early stages might be partly responsible, along with better treatments, for the lowered breast cancer death rates, she added.

Cancer rates are often age-adjusted to compare rates among groups with different numbers of young, middle, and older ages.

For example, comparing Florida and Alaska cancer rates might make it look as though moving from Alaska to Florida would triple a person's cancer risk. But in reality, Florida simply has more people in older age groups that are more likely to develop cancer.

Earlier reports corrected for this by using age-adjusted statistics, which were calculated based on the makeup of the US population in 1970.

But this year for the first time, the model for age adjustment was based on the results of the 2000 US census. This update will allow for more accurate age-adjusted rates based on the US population as it is now, compared to what it was 30 years ago.

But because of this, the latest statistics can’t be compared directly to those from previous years. The statistics for many cancers would look much higher than in previous years, even though they really haven’t changed much. The most accurate comparison of earlier rates with the most recent ones can be found in the new report, Edwards noted.

"The projection of future cancer cases was new this year and underscores how large the impact of the future aging and growth of the population will be on the future cancer burden," said Michael Thun, MD, vice president of epidemiology and surveillance research for the ACS.

The authors noted that the look into the future clearly shows the need to quicken the pace of research, increase cancer prevention and screening, and improve therapies, including treatments for an aging population, many of whom may have other problems associated with age besides cancer.

NCI Director Andrew C. von Eschenbach, MD, said, "The continuing decline in the rate of cancer deaths once again affirms the progress we have made against cancer, but the report also highlights the need for an acceleration of research as the population of the United States ages."