The charts appear in a report in the June 5 Journal of the National Cancer Institute by DMS and Veterans Affairs Outcomes Group physicians Steven Woloshin, Lisa Schwartz and H. Gilbert Welch.
People are regularly confronted with cancer risk information presented in ways that highlight the magnitude of the risk but provide little context. For example, "This year, approximately 182,800 women in the US will be diagnosed with invasive breast cancer, and approximately 40,800 women will die from breast cancer." Without context, such messages may lead people to overestimate the risks they face. In the example above, if you are a 40 year-old woman who has never smoked, your chance of dying from breast cancer in the next ten years is 0.2 percent and stays below one percent until the age of 70.
The charts are designed to be simple, low-tech tools that can be used anywhere. They put cancer in context by placing the 10-year chance of dying from various causes side by side. To facilitate their use in a clinical setting, the risk charts include data for a range of ages on a single page. There are separate charts for male and female smokers and never smokers.
Woloshin said, "We believe that our risk charts will help people better understand and compare the important health threats they face. The charts could be posted in clinic offices or distributed to patients for easy reference when decisions are made. Because the charts give people a sense of how much smoking adds to their chance of dying at every age, they may also be useful in smoking prevention and cessation efforts."
The Dartmouth team used the Multiple Cause of Death File from the National Center for Health Statistics and population estimates from the US Census to calculate death rates for heart disease, stroke, lung, colon, breast and prostate cancer, AIDS, pneumonia, influenza, and accidents, as well as death rates from all causes. They then calculated the 10-year chance of dying for each cause for men and women in 5-year age intervals from age 20 to age 90 and estimated these chances for current smokers and for never smokers.
The researchers caution that the charts only present data about mortality, not disease incidence. Judgments about incidence are far more ambiguous than those about death. Also, risk estimates are not completely individualized. Patients with important disease risk factors, such as a family history of a disease, might obtain more precise estimates of risk from that disease with a customized assessment. The team did, however, account for what are arguably the most important risk factors for death: age, sex and smoking.
Woloshin and Schwartz are also affiliated with Dartmouth's Norris Cotton Cancer Center. For more information, contact Lisa Schwartz, MD, at email@example.com.
DMS news is on the web at www.dartmouth.edu/dms/news.