Studying stage 0: Questions about DCIS

A major study this week in JAMA Oncology, which looked at mortality rates following a diagnosis of ductal carcinoma in situ (DCIS), provided some important insights and challenged preconceived notions.

It also spurred even more questions.

There’s a lot to unpack in the study, authored by Steven A. Narod, MD, of the University of Toronto and Women’s College Hospital in Toronto, and colleagues. Among the headline findings:

• While physicians have long wondered how to approach DCIS—is it a lethal cancer in itself or merely a precursor to one?—researchers found some cases of DCIS have “an inherent potential for distant metastatic spread.”
• Breast cancer-specific mortality for those with DCIS was 3.3 percent at 20 years of follow-up, which is 1.8 times greater than the rate for the general U.S. population.
• For those diagnosed with DCIS, the risk of dying from breast cancer was elevated for women who later experienced an ipsilateral invasive cancer, those who were diagnosed before age 35 and black women.
• While radiotherapy and mastectomy are used to successfully reduce the rate of ipsilateral invasive recurrence, these techniques did not improve breast cancer-specific mortality.

What to make of all this? Coverage in both professional publications and popular media focused on many different aspects of the study. Some highlighted the relatively low rate of mortality from breast cancer after DCIS—an associated editorial in JAMA Oncology even said the overall rate was “not dissimilar” to American Cancer Society statistics for the average woman.

Others took almost the opposite angle, focusing on how DCIS could be lethal even without an invasive recurrence. More than half the women in the study who died from DCIS did not have an invasive breast cancer.

The New York Times, meanwhile, homed in on the fact that many women have undergone radiotherapy or mastectomy in an attempt to prevent a recurrence, and it appears that this strategy would have done little to reduce breast cancer-specific mortality rates in this population.

Given that the optimal strategy for mammographic breast cancer screening is such a topic of debate among those weighing early cancer detection against the potential for overtreatment, the study spurs a number of questions on how to approach DCIS once its detected by screening.

In that associated editorial, Laura Esserman, MD, MBA, and Christina Yau, PhD, both of the University of California, San Francisco, wrote that even though the study suggests we should “stop telling women that DCIS is an emergency and that they should schedule definitive surgery within two weeks of diagnosis,” more work on differentiating high- and low-risk DCIS is needed.

“We should continue to better understand the biological characteristics of the highest-risk DCIS (large, high grade, hormone receptor negative, HER2 positive, especially in very young and African American women) and test targeted approaches to reduce death from breast cancer.”

Esserman and Yau continue: “Ductal carcinoma in situ may best represent an opportunity to alter the environment of the breast. For the lowest-risk lesions, observation and prevention interventions alone should be tested.”

-Evan Godt
Editor – Health Imaging