Biostatistician uses statistical and computer modeling for policy development in prostate cancer research

Ruth Etzioni, Ph.D., a biostatistician, is a member of the Public Health Sciences Division at Fred Hutchinson Cancer Research Center.

She focuses on statistical and computer modeling for policy development, with a focus on prostate cancer research. A critical component of this work is the estimation of natural history and progression of disease, which then forms a basis for modeling comparative- and cost-effectiveness of alternative interventions.

Etzioni's models of disease have been used to estimate the lifetime probabilities of prostate cancer and its outcomes, study the extent of overdiagnosis and overtreatment associated with prostate cancer screening, and quantify the roles of screening and advances in primary treatment in explaining population mortality declines.

Overdiagnosis and overtreatment of prostate cancer
The prostate-specific antigen (PSA) test has been responsible for a dramatic increase in the incidence of prostate cancer diagnoses in the United States. Originally developed to monitor disease progression, the PSA test has widely been used for early detection since its introduction in the mid-1980s, but there has been no rigorous assessment of its effectiveness for such screening.

As use of the PSA test has become prevalent, overdiagnosis has become a concern as it can result in unnecessary worry, expense and painful procedures that can result in side effects ranging from urinary incontinence to sexual dysfunction in men who might not have ever experienced any morbidity or risk without the diagnosis.

Overdiagnosed prostate cancer cases are cases that never would have been detected in a patient's lifetime without screening. According to Etzioni, overdiagnosis has always been a concern in prostate cancer screening because it's been known for a long time that there are many silent cases, particularly in older men, that would never progress to lethal disease. The extent of overdiagnosis associated with PSA screening cancers was not known until Etzioni and her group estimated it using data on US prostate cancer incidence under screening. While their results showed that about one in four screen-detected cases were overdiagnosed, their estimates were lower than other studies based on US and European data.

In their recent research, Etzioni and colleagues have indicated that less frequent PSA tests in men at low risk of prostate cancer would substantially reduce the likelihood of overtreatment while increasing the risk of death only slightly. Their research has indicated that testing men less often or raising the threshold for PSA tests in older men could reduce the number of tests by nearly 60 percent and the number of false positives—which often lead to painful biopsies—by almost half.

Etzioni is a member of three national panels on prostate cancer early detection and serves on the American Cancer Society's newly formed Guideline Development Panel. Her work on prostate cancer modeling is done as part of the National Cancer Institute's Cancer Intervention and Surveillance Modeling Network (CISNET) consortium, for which she serves on the steering committee and is the principal investigator of the Prostate Cancer Coordinating Center. Etzioni is also principal investigator for the Biostatistics Core of the Pacific Northwest Prostate Cancer SPORE (Specialized Program in Research Excellence) program.