Overall US cancer death rates have continued to decline since the early 1990s among men, women, and children, but excess weight and lack of sufficient physical activity contribute to the increased incidence of many individual cancers, may worsen prognosis, and adversely affect quality of life for cancer survivors.
Overall cancer mortality has been declining among children since the 1970s and among adults since the 1990s, according to the new Annual Report to the Nation on the Status of Cancer, 1975-2008, Featuring Cancers Associated With Excess Weight and Lack of Sufficient Physical Activity, issued by the CDC, the North American Association of Central Cancer Registries, the National Cancer Institute, and the American Cancer Society, and published in the journal Cancer (2012;118:2338-2366). Trends in death rates for the most recent 10-year period (1999-2008) show an average decrease of 1.7% per year among men and an average decrease of 1.3% per year among women as well as among children from birth to 19 years.
The overall rate of new cancer diagnoses among men fell by an average of 0.6% per year between 2004 and 2008. For women, incidence rates declined 0.5% per year from 1998 to 2006, and remained level from 2006 through 2008.
The report highlighted the following reductions in mortality and incidence rates of specific cancers:
• Lung cancer mortality among women decreased for the second consecutive year, and has been decreasing for men since the early 1990s.
• Colorectal cancer incidence rates declined for both men and women from 1999 through 2008.
• Breast cancer incidence rates among women decreased from 1999 through 2004, and remained level from 2004 through 2008.
Conversely, incidence rates for melanoma and pancreatic, kidney, thyroid, and liver cancers increased from 1999 through 2008.
The authors of the report note that the continued declines in mortality from all cancers combined indicate progress in improved treatments, increased screening and early detection, and primary prevention in the form of education about risk factors and promotion of healthy behaviors. However, as indicated by the title of this year’s report, the document emphasizes the increased cancer risk associated with excess weight (overweight or obesity) and lack of sufficient physical activity (less than 150 minutes of physical activity per week).
A special section on excess weight, lack of sufficient physical activity, and associated cancers featured in the report states that each increase of 5 kg/m2 in body mass index (BMI) is associated with an increase of 30% to 60% in risk for endometrial cancer, adenocarcinoma of the esophagus, and kidney cancer, and an increase of 13% to 18% in risk for colorectal, pancreatic, and postmenopausal breast cancers. Excess weight may also contribute to poorer survival in breast, colorectal, and prostate cancers, and with incidence of late-stage prostate cancer.
Similarly, lack of sufficient physical activity has been associated with a 30% to 40% increased risk of colon cancer, postmenopausal breast cancer, and endometrial cancer. Physical activity after a breast or colon cancer diagnosis is associated with reduced all-cause and cancer-specific mortality.
The authors point out that considerable evidence suggests that excess weight also may be associated with increased risk of gallbladder, liver, thyroid, and hematopoietic cancers, and lack of sufficient physical activity is associated with increased risk of colon, endometrial, and postmenopausal breast cancers, and possibly with premenopausal breast cancer. ONA