In an e-mail interview, E. Shelley Hwang, MD, an expert who has coauthored several papers on ductal carcinoma in situ (DCIS), weighed in on the two abstracts about management of DCIS featured in this issue of The ASCO Post—one presented by Melissa L. Pilewskie, MD (perioperative MRI in DCIS, page 12)1 and the other, by Naomi B. Boekel, MSc (radiation therapy in DCIS, page 12).2 Dr. Hwang is Professor of Surgery and Chief of Breast Surgical Oncology at Duke University Medical Center in Durham, North Carolina.
Perioperative MRI Adds Little Value in DCIS
Regarding Dr. Pilewskie’s abstract on perioperative MRI, Dr. Hwang said, “I agree that the routine use of MRI in the setting of DCIS is not indicated, and this study supports that view. We, and others, have reported that use of MRI is associated with a higher likelihood of mastectomy, regardless of MRI findings, and this has recently been substantiated in a meta-analysis by Houssami and colleagues. These observations indicate that the routine use of MRI to guide surgical therapy adds little value to mammography alone. Further, there is danger of harming patients by inappropriate screening at low or intermediate breast cancer risk.”
Dr. Hwang pointed out that other potential uses for MRI warrant further exploration. “For example, we are participating in a national study sponsored by the Alliance cooperative group, which will determine the value of MRI in assessing response of DCIS to medical, as opposed to surgical treatment. Such trials may, in the future, help determine which cases of DCIS are most likely to require aggressive treatment and which may be amenable to surveillance alone,” she explained.
Radiation in DCIS and Cardiovascular Concerns
Turning to Ms. Boekel’s paper on the cardiovascular safety of radiation therapy in the setting of DCIS, Dr. Hwang cited some concerns.
“The most reassuring observation from this study is that patients undergoing radiation for left-sided DCIS [involves radiation to a portion of the heart] had the same cardiovascular mortality as those undergoing right-sided radiation,” she stated. “However, it is important to note that these results conflict with those published earlier this year by Darby and colleagues, who found a significantly increased risk for major coronary events from chest wall radiation, which was dose-dependent. This raises the issue of whether the current study may have been underpowered to show a difference between groups.”
Other concerns include additional short-term toxicities as well as serious but rare late effects (eg, secondary cancers). Dr. Hwang added, “These [other] morbidities must be considered when administering radiation as part of treatment for a disease which we know has negligible impact on breast cancer mortality.”
At this point, there is no way to determine which DCIS will progress to invasive cancer. “Going forward, we will have to redouble our efforts to identify those [patients with] DCIS at highest risk for progression to invasive cancer and to limit treatment for those [patients with] DCIS at lowest risk of progression,” Dr. Hwang said.
Work is progressing on identifying both clinical and molecular markers of poor prognosis. “Although there are limitations to any prognostic panel, these predictors have helped to lay the framework to encourage conversations with patients about the tradeoffs between the benefits and morbidities [as well as costs] of treatment. The morbidity of adjuvant treatments remains the same, whether given for low- or high-risk disease. Thus we must continue to question whether the use of radiation can be adequately justified by long-term health benefits in low-risk clinical scenarios,” Dr. Hwang said. ■
Disclosure: Dr. Hwang reported no potential conflicts of interest.
References
1. Pilewskie MD, Olcese C, Eaton A, et al: Association of MRI and locoregional recurrence rates in ductal carcinoma in situ patients treated with or without radiation therapy. 2013 Breast Cncer Symposium. Abstract 57. Presented September 7, 2013.
2. Boekel NB, Schaapveld M, Gietma JA, et al: Cardiovascular morbidity and mortality in patients treated for ductal carcinoma in situ of the breast. 2013 Breast Cancer Symposium. Abstract 58. Presented September 7, 2013.
