New studies aim to help doctors, patients, and policymakers understand cancer prognosis, survival

Three papers in the survival monograph published by the Journal of the National Cancer Institute, co-authored by Dartmouth's Norris Cotton Cancer Center investigators Steven Woloshin, MD, MS, and Lisa Schwartz, MD, MS, aim to help doctors, patients, and policymakers better understand cancer prognosis and survival.

"Survival statistics are deceptively simple - explaining the concepts clearly for the general public is the big challenge," said Drs. Woloshin and Schwartz.

In the first paper, "When Do Changes in Cancer Survival Mean Progress? Insight From Population Incidence and Mortality," first author Hyunsoon Cho, PhD, explained that the statistics most people see about cancer, such as those used to judge whether we are making progress against cancer, are easily misunderstood. "Increasing survival sounds like good news, decreasing survival sounds like bad news. But the story is more complicated," Cho said. Improved survival represents progress when it is accompanied by a decreased burden of disease: fewer people being diagnosed or dying from cancer. But improved survival can also occur even when disease burden is increased. Cho's paper is written to help people know how to use and interpret survival statistics.

To explain another area of common misunderstanding, Nadia Howlander, PhD, wrote "Providing Clinicians and Patients with Actual Prognosis: Cancer in the Context of Competing Causes of Death," . The paper differentiated between "cancer prognosis," which isolates the effect of cancer on the chance of surviving, and "actual prognosis," which is a person's chance of dying from cancer, from other causes, or surviving.

"We encourage registries to report both kinds of prognosis," said Howlander. "Cancer prognosis statistics are useful for researchers and policy makers because they clarify whether increased survival among cancer patients reflects improvements in the prevention or treatment of cancer versus the prevention or treatment of competing causes of death, such as cardiovascular disease. Actual prognosis is useful because it estimates what is likely to happen to individuals diagnosed with cancer."

In the third paper, "Cancer Survival: An Overview of Measures, Uses, and Interpretation," Angela Mariotto, PhD wrote that, "In common usage, survival and mortality are two sides of the same coin: a person is either alive or dead. But in cancer statistics, survival and mortality are two sides of different coins." Early diagnosis, over diagnosis, and genuinely longer survival may all have an effect on cancer statistics.

Cancer and actual prognosis can differ a lot, especially as people get older and have other serious health problems that may cause death before the cancer. The Dartmouth team, led by Woloshin and Schwartz, says it is important for clinicians, patients, and communicators to understand how to use and interpret common cancer survival statistics to help guide both individual and policy-level decision making.

The National Cancer Institute is adopting the formats developed by Woloshin and Schwartz for use in presenting survival statistics on their website.