In 1998, the American Cancer Society (ACS) set a challenge goal for the United States to lower cancer incidence by 25% between 1992 and 2015. At about the midpoint (2004), overall cancer incidence rates had declined at a rate of about 0.6% per year, about half the pace needed to achieve the 25% goal by 2015
In 1998, the American Cancer Society (ACS) set a challenge goal for the United States to lower cancer incidence by 25% between 1992 and 2015. At about the midpoint (2004), overall cancer incidence rates had declined at a rate of about 0.6% per year, about half the pace needed to achieve the 25% goal by 2015. Similarly, ACS estimates that it goal of reducing cancer mortality by 50% from 1990 to 2015 may also be only half met.
"New understandings of preventable factors are needed, and new efforts are also needed to better act on our current knowledge about how we can prevent cancer, especially by continuing to reduce tobacco use and beginning to reverse the epidemic of obesity," the investigators wrote (Sedjo RL et al: CA Cancer J Clin 57:326-340, 2007).
The researchers calculated cancer incidence trends using SEER data, and presented data on delay-adjusted incidence trends for all cancer sites; all cancer sites without prostate cancer included; all cancer sites stratified by sex, age, and race; and 20 selected cancer sites.
Since cancers may be reported to registries years after the initial diagnosis, delay-adjusted rates were estimated to account for such delays in reporting. Rates for all cancers were calculated without prostate cancer to avoid the effects of PSA screening. All rates were age adjusted to the 2000 US standard population.
From 1992 to 2004, cancer incidence rates fell by about 8% (0.6% per year). Incidence increased in the early 1990s apparently due to a rise in prostate cancer incidence associated with increasing use of PSA screening.
"The declines in cancer incidence were most apparent among men and among those aged 65 years and older," the authors said. Declines among men are related primarily to declines in lung and prostate cancer. The reason for the declines in older people is unclear, but may be related to the fact that long-term benefits of smoking cessation are more apparent with advancing age and to the wide access to clinical preventive services in the Medicare system, including colorectal and cervical screenings.
Although decreasing trends were similar in all races, African Americans continued to have a higher cancer incidence than whites.
Trending down in incidence were cancers of the prostate, lung (men only), colorectum, ovary, oral cavity, stomach, and cervix uteri. Invasive breast cancer began to trend downward after 1999, and lung cancer incidence in women has been stable in recent years.
No downturn was seen in multiple myeloma, non-Hodgkin's lymphoma, leukemia, or in cancers of the corpus uteri, bladder, pancreas, or brain, and rates actually increased for melanoma and cancers of the kidney, liver, thyroid, and esophagus.
The investigators said there has been "mixed success" in reducing the prevalence of major cancer risk factors. Although historical declines in tobacco use and use of HRT in women have contributed to declines in the incidence of some cancer sites, "these favorable changes are somewhat offset by the increasing prevalence of obesity, which contributes to higher risk for many types of cancers," the investigators said.
The researchers also noted that mammography rates have declined somewhat in recent years. On a more optimistic note, screening for colorectal cancer has been rising, and colorectal cancer is "on target" to meet the 2015 goal.