DCIS Carries Three-Fold Risk of Death

Women who have ductal carcinoma in situ (DCIS) are more than three times as likely to die from breast cancer that are women in the general population, according to a new study.

In a study published Sept. 16 in JAMA Open Network, a research team from the University of Toronto determined women with DCIS have a 3.3-fold higher risk of dying from breast cancer than women the same age who do not have the disease. And, the risk is higher among young women and black women, they said.

“In the population studied, the risk of dying of breast cancer…suggests that our current treatment focus on preventing invasive recurrence is insufficient to eliminate all deaths from breast cancer after DCIS,” said the team led by Vasily Giannakeas, MPH, a doctoral candidate at the University of Toronto and Women’s College Research Institute.

While DCIS currently accounts for 30 percent of all cancers picked up in breast cancer screening, there is no consensus over whether it is an early-stage cancer that requires treatment before it progresses or if it should simply be monitored over time. It has also been suggested that searching for these cancers leads to overdiagnosis, and, therefore, unnecessary treatment. Giannakeas’s team contend their results support the argument for putting more emphasis on DCIS detection.

To determine the actual risk of death associated with DCIS, the team compared actual deaths with estimated deaths for women who received a DCIS diagnosis between 1995 and 2014. They pulled Surveillance, Epidemiology, and End Result data on 144,524 women treated surgically for DCIS. Women ranged in age from 25 to 79 at the time of diagnosis, and team tracked their outcomes either until they died, were lost to follow-up, reached 20 years post-diagnosis, or until the study ended in December of 2016.

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The team calculated the standard mortality ratios (SMR) for these groups, leading them to postulate that 459 women from the entire study population would die from breast cancer if they had not developed DCIS. In actuality, 1,540 succumbed to the disease, resulting in a 3.36 SMR that indicates women with DCIS die three times as often as anticipated according to their year of diagnosis and age.

SMRs based on age and race also differed significantly, the team determined. Specifically, women under age 40 were 12 times more likely to die than the women in the healthy cohort, and black women were 7.6 times more likely. And, black women over age 50 fared worst with a 12.1 SMR.

Overall, the team said, the cohort had a 3.3 percent cumulative 20-year risk of breast cancer-specific mortality – a rate of risk that is too low to recommend chemotherapy across the board for women with DCIS. However, some subsets of women face higher cumulative risks, potentially making chemotherapy necessary. For example, black women over age 50 had a breast cancer-specific mortality risk of 8.1 percent.

Based on these results, the team recommended additional studies that could shed light on which patients with DCIS are at a higher mortality risk. Such investigations could improve treatment options.

“The current approach is to identify women with a high risk of local recurrence and treat them with radiotherapy initially and with chemotherapy at time of invasive cancer according to the clinical profile,” the team said. “It is challenging to identify patients with DCIS who are at high risk of dying; it might be possible to address this question using a case-controlled approach and compare pathological specimens and molecular expression and other demographic criteria for those who died and those who survived.”