THURSDAY, March 31 (HealthDay News) — The rate of new cancers in the United States has dropped by almost 1 percent a year and the rate of death from cancer has fallen 1.6 percent a year, a new report shows.

These declines, seen between 2003 and 2007, continue a trend that began in the 1990s, the researchers added.

Importantly, this is the first time a drop in the rate of deaths from lung cancer among women has been seen, coming a decade after lung cancer death rates started declining in men, they noted.

“The drop in lung cancer rates among women is due to women quitting smoking,” said report co-author Lynn Ries, a health statistician at the U.S. National Cancer Institute. “Women started smoking a lot later than men, so the peak in the mortality rate occurred a lot later,” she added.

The report is the work of researchers at the North American Association of Central Cancer Registries, the U.S. National Cancer Institute, the U.S. Centers for Disease Control and Prevention and the American Cancer Society. It is published in the March 31 online edition of the Journal of the National Cancer Institute.

Although cancer rates are declining in adults, there has been a rise in cancers diagnosed in children. Most of these involve increases in the incidence of leukemias. However, the rate of death from cancer among children is declining, Ries noted.

Ries noted that the reasons for the increase in childhood cancers isn’t clear.

Among men, the overall cancer rate has remained about the same. In fact, cancer rates in men would have also shown a decline, except for a small rise in the rate of prostate cancer, according to the report.

One section of the report focuses specifically on both brain and nervous system cancers and benign tumors. According to the report, benign brain tumors are twice as common as cancerous ones, Ries said.

In fact, benign brain tumors account for 75 percent of those in adults and 33 percent of brain tumors in children.

“Cancer is not one disease,” Ries said. “The rates for some are going up and some are going down, and there are different patterns for men and for women,” she said.

For example: Among men, rates of lung, colon, rectum, oral, pharynx, stomach and brain cancers have dropped. But, rates of kidney, pancreas and liver cancers and melanoma have risen.

While, among women, rates of breast, lung, colorectal, uterine, cervical, bladder and oral cancers have dropped. But, rates of kidney, pancreas and thyroid cancers, and leukemias and melanomas, have risen.

Racial disparities in cancer still exist, the researchers noted, and the cancer death rate is highest among black men and women, even though the cancer death rate for blacks dropped significantly from 1998 to 2007.

In addition, the highest rates of new cancers seen between 2003 and 2007 was among black men. Among women, the highest rate was seen among white women, according to the report. Among both black and white women, breast cancer was the most commonly diagnosed cancer.

These differences may be due to variations in risk behaviors, socioeconomic status and access to and use of screening and treatment, the researchers said.

Dr. Joseph Rosenblatt, interim director of the Sylvester Comprehensive Cancer Center at the University of Miami Miller School of Medicine, attributes declining cancer rates and deaths to a variety of factors.

The reduction in the rate of some cancers is mostly due to lifestyle changes, especially people not smoking, he said.

On cutting the death rate, Rosenblatt noted that “we have evolved better screening, better diagnostics and better classification of cancers and better treatments,” he said. “We are beginning to see significant decreases.”

On the other hand, “we really don’t have a good explanation for why childhood cancers have increased,” Rosenblatt said. Most of the rise is in leukemias, and “the good news is that most leukemias are curable in children,” he said.

Rosenblatt expects to see even fewer cancer deaths in the future. “The treatments on the horizon are extraordinary,” he said.

This change is being brought about by better understandings of how different cancers work and then developing targeted treatments, Rosenblatt said.

“The war on cancer has been successful,” he concluded.