The war against cancer got some recent good news nationally but bad news globally, with one report trumpeting a record, sustained decline in new US cancer cases, even as another found cancer poised to beat heart disease as the world's #1 killer.
First, the good news: an annual report released in late November by the U.S. National Cancer Institute, the American Cancer Society and other major scientific groups found that the rate of newly diagnosed cancers fell by 0.8 percent each year from 1999 to 2005, the longest sustained decline to date. The drop in incidence occurred alongside an average 1.8 percent annual decline in cancer deaths, continuing a 15-year trend.
The report's authors attribute the decline in deaths to improvements in screening, especially for breast, colorectal and prostate cancers, the adoption of healthier lifestyles, and advances in treatment.
The reasons for the drop in new cases remains more uncertain—experts say it might be a ‘real’ finding or it could be due to irregularities in screening that are allowing cancers that might have been detected in the past to go undetected now.
For example, the rate of new cases of prostate cancer fell by 4.4 percent annually between 2001-2005, a big change from the steady 2.1 percent annual rise in incidence experts had noted in the 1990s. But prostate screening rates have also recently flattened out, according to the report’s lead author, Dr. Ahmedin Jemal, strategic director for cancer surveillance at the American Cancer Society. "It's always difficult to interpret the incidence rate," Jemal told The New York Times.
Still, other national statistics were encouraging. According to the report, published in the Dec. 3 issue of the Journal of the National Cancer Institute, the incidence of breast cancer fell by 2.2 percent year on year from 1999 to 2005, perhaps linked to a concurrent decline in the number of women using hormone replacement therapy. And the rate of colon cancer dropped by 3 percent between 1998-2005, alongside a slow but steady rise in the use of colonoscopy.
Not all tumor types were receding in incidence, however. American men charted increases in rates of new cases of cancer of the liver, kidney and esophagus, and for melanoma and myeloma; while women faced increases in new cases of thyroid, pancreatic, brain/nervous system, bladder and kidney tumors, as well as the #1 cancer killer, lung cancer. Rates of leukemia and non-Hodgkin's lymphoma rose for both sexes.
These last statistics suggest that the battle against cancer is far from over, the experts said. The observed overall decrease in cancer incidence is "highly encouraging," the report’s authors wrote. "However, this must be seen as a starting point rather than a destination."
A much more grim report from the World Health Organization suggests that cancer is making inroads globally, however. In their report released Dec. 9, WHO experts now predict that by 2010 cancer will overtake heart disease as the world's leading killer, causing more deaths than AIDS, malaria, and tuberculosis combined. Unless current trends reverse, 27 million people will be newly diagnosed with cancer by 2030, more than double the 12 million new cases reported worldwide in 2007.
The reason? Increasingly, people in developing nations are adopting cancer-linked 'Western' lifestyles, including diets linked to obesity, more sedentary behaviors, and most importantly, smoking. Overall, cancer cases and deaths are expected to grow 1 percent per year, with the biggest jumps expected in China, India and Russia. "The rapid increase in the cancer burden represents a real crisis for public health and health systems worldwide," the report's authors said.
