Death rates from some of the most common cancers are dropping, according to the latest projections compiled by the American Cancer Society. Americans this year are less likely to die from lung, colon, breast, and prostate cancer, ACS experts report in Cancer Facts & Figures 2004, an annual estimate of cancer incidence and death rates in the United States.

The decline in deaths is due to new treatments and wider use of tools for finding cancer early, when it is most treatable, the report says.

Nevertheless, cancer remains the second leading cause of death in the US, killing more than 1,500 people a day. Only heart disease claims more lives. More than 1.3 million people are expected to be diagnosed with some form of cancer in 2004, and about 563,700 people are expected to die from this disease, according to the report.

Many of those cases and deaths could be prevented with lifestyle changes. More than 180,000 cancer deaths in 2004 will be caused by tobacco use, the report says, while about one-third of cancer deaths are related to poor nutrition, lack of physical activity, and excess weight.

"Cancer is not an inescapable fact of life," said Michael Thun, MD, vice president of epidemiology and surveillance research for ACS. "Things we do, and social policies, make a huge difference."

Public health officials face a particularly great challenge in addressing the problem of physical inactivity and obesity, Thun said.

"The pieces that are missing in terms of prevention are effective ways by which communities and social policies can help people maintain a healthy body weight and get regular physical activity," he said. "The big thing to tackle is, What are the interventions that will actually begin to turn it around?"

Lung cancer is the second most common cancer, and it's the top cancer killer of both men and women. Although it accounts for just 13% of cancer cases, lung cancer is responsible for nearly one-third of cancer deaths in men (32%) and one-quarter of those in women (25%). About 173,770 new cases and 160,440 deaths are expected in 2004. Smoking will be the direct cause of about 87% of those deaths.

Tobacco control efforts have had a dramatic impact, however, particularly in men. The lung cancer death rate among men has been decreasing significantly, by nearly 2% per year, since the early 1990s. This drop is mostly due to reductions in smoking among men, which has led to fewer cases of the disease.

But the same is not true of women. Lung cancer deaths in women, which had been rising until the 1990s, have reached a plateau; they have not yet started to decline.

Early detection and better drugs are credited with reducing deaths from breast cancer, the most common cancer among American women (other than skin cancer). More women were diagnosed with breast cancer in the 1990s, but this increase was seen only among women age 50 and older. In spite of this, death rates dropped by more than 2% per year among women overall, while women under age 50 saw even greater declines. Today, about 97% of women with localized breast cancer survive 5 years after their diagnosis.

About 215,990 new cases of invasive breast cancer and 59,390 cases of in situ breast cancer are expected to be diagnosed in women in 2004; about 40,110 women are expected to die from this disease. Breast cancer can also strike men, though it is rare. About 1,450 new cases and 470 deaths are expected among men in 2004.

Prostate cancer is the most common cancer among men, and detection rates for this disease have been on the rise, most likely because of wider use of the PSA screening test. About 230,110 new cases of prostate cancer, and 29,900 deaths, are expected in 2004. African-American men are more likely than white men to develop prostate cancer and die from it. However, deaths from prostate cancer in both races have been declining since the early 1990s. Today, around 86% of prostate cancer cases are discovered at an early stage, when 5-year survival is 100%.

Despite these positive findings, Thun said there is a lot of room for improvement.

"For both breast and prostate cancer, there are tests that effectively diagnose the disease early, but in the clinical management of people who have those early cancers, we have a lot to do in sorting out the appropriate level and aggressiveness of treatment," he said.

More needs to be done to find genetic markers that can help doctors decide which cancers need to be treated aggressively and which can be safely be watched carefully but left untreated, he said. Developing better treatments is also important. Researchers have made great progress in developing more effective, less toxic medications for some of the less common cancers, such as Gleevec for chronic myelogenous leukemia. Similar drugs that target more common cancers are needed, Thun said.

Public health officials also need to do more to increase screening rates for colorectal cancer, the third most common cancer among both men and women in the US and the third deadliest in both groups. About 146,940 new diagnoses and 56,730 deaths are expected in 2004.

In recent years, fewer people have been getting this disease and fewer have been dying from it, likely due to increased screening, which can find and remove precancerous polyps before they become deadly tumors. Still, Thun pointed out, fewer than half of Americans who should get screened actually do so.

Finding colorectal cancer early makes a big difference. About 90% of patients with localized disease survive 5 years beyond their diagnosis, but once the cancer has spread to nearby lymph nodes or organs, that number decreases to 66%. Unfortunately, just 38% of colorectal cancers are discovered at the earliest, most curable stage.

This year's Facts & Figures report also addresses how cancer differently impacts minority racial/ethnic and low socioeconomic groups. For instance, racial minorities have substantially lower survival rates from cancer than do whites. African Americans fare the worst. Death from cancer is 40% higher among African American men than white men, and 20% higher among African American women compared with white women.

Poverty, which disproportionately affects racial and ethnic minority groups, plays a big role in this gap, Thun explained. People with no health insurance may be unable to get important cancer screening tests that find the disease early, for instance. Or if they are diagnosed, people with low incomes may be unable to complete treatment because they can't afford to take time off work, or because they work more than one job. Poor communities may have fewer healthful fruits and vegetables in their local supermarkets, and residents may be unable to afford these foods.

"Many of these things are difficult to turn around," Thun acknowledged, "but the thing that is really important is to keep pointing out the problems and keep pressure on to find things that can be modified."