Dr. Mai Elezaby of the University of Wisconsin School of Medicine and Public Health discussed the overdiagnosis and overtreatment controversy that surrounds ductal carcinoma in situ on Tuesday at the annual ARRS meeting in New Orleans.

“Overdiagnosis and overtreatment have typically been defined as cancers detected and treated as a result of screening tests that would not have otherwise been clinically apparent in a patient’s lifetime," she told the audience in her session on breast imaging.

Elezaby noted that most of the data on DCIS overdiagnosis was calculated using historic data, prior to the introduction of the College of American Pathologists guidelines in 2009. Previously, there were multiple different classification systems, which resulted in significant variability in the interpretation of DCIS.
“There have also been technological advancements in the field of pathology that change the diagnosis of DCIS," she added. "What we currently know as low-, intermediate-, or high-grade DCIS might not apply to some of the data from new studies.”

Randomized control trials are the current gold standard for calculating overdiagnosis. The patients are randomly placed in either the screening or non-screening group and the researchers assess the incidence rates of breast cancer in both groups and subtract them to determine the rate of overdiagnosis.

A study from 2012 primarily evaluated SEER data to determine changes in breast cancer incidence in the U.S. population over time. The researchers calculated that the overdiagnosis rate for DCIS and invasive carcinoma was 31 percent.

A study from the same time period used the Connecticut Tumor Registry and estimated that the breast cancer incidence increased 1.2 percent per year. A UK study estimated that it increased between .7 percent and 2.3 percent per year and a study from Asia, Africa and Eastern Europe estimated 5 percent per year.

“The estimates of overdiagnosis are highly dependent on the method of calculation and the scientific rigor," said Elezaby.

She emphasized that the expected breast cancer incidence rate has to be accounted for in order to calculate an accurate overdiagnosis rate. That's because the incidence of breast cancer normally increases in a population over time.

Going forward, Elezaby believes there needs to be more of a focus on diagnostic accuracy for DCIS as well as identifying patient-specific imaging markers that can characterize the disease and stratify patients for treatment.

Research from the ECOG-ACRIN trial is investigating the use of MR imaging and gene expression in diagnosing patients with DCIS. The primary outcome for the trial is to determine the proportion of breast conservation therapy candidates who proceed to mastectomy based on MR features or on surgical planning.

“Our emphasis as an imaging community and medical community in general should focus on research to identify patient-specific risk stratification to tailor treatment, rather than limit access to it," Elezaby concluded.

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