New research in the November 2019 issue of JNCCN—Journal of the National Comprehensive Cancer Network examines the implications of invasive breast cancer after breast-conserving treatment for ductal carcinoma in situ (aka DCIS, a form of non-invasive breast cancer) and which factors could impact overall survival. The findings can help patients with decision-making for local treatment based on long-term outcomes and consideration of which recurrences may warrant a more aggressive treatment approach.

“We think it’s critical for physicians and patients to have a careful discussion weighing the pros and cons and individual patient characteristics and preferences before selecting treatment for DCIS,” said lead author Rinaa S. Punglia, MD, MPH, Dana-Farber Cancer Institute/Brigham and Women’s Hospital. “Our results provide additional factors for them to consider, especially for younger patients without estrogen receptor (ER) expression, where radiation therapy could limit salvage options in the future if the disease returns.”

“It is reassuring that overall, secondary invasive breast cancer following breast conserving therapy for DCIS is very low,” commented Janice Lyons, MD, Case Comprehensive Cancer Center/University Hospitals Seidman Cancer Center and Cleveland Clinic Taussig Cancer Institute, a member of the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines^®) Panel for Breast Cancer who was not involved with this research. “We know that adjuvant radiotherapy following breast conserving surgery for DCIS substantially reduces the risk of subsequent invasive disease on the same side. However, this study suggests that for those who do develop an invasive secondary breast cancer on the same side, treatment may be more challenging. I agree that a thoughtful discussion with each patient, incorporating shared decision-making and all available clinicopathologic information, is important to determine the preferred treatment approach for DCIS.”

The researchers used the National Cancer Institute’s Surveillance, Epidemiology, and End Result (SEER) database to study 3,407 patients who were treated with breast-conserving surgery (with or without radiation therapy) for DCIS between 2000 and 2013, and subsequently developed a stage I-III invasive secondary breast cancer. Out of those 3,407 patients, 150 deaths were reported; 89 of them in patients who were initially treated with radiation therapy, and another 61 who were not.

The findings showed that those patients who developed a second cancer in the same breast were more likely to be younger, and to lack ER expression, which are characteristics associated with more aggressive cancers. However, this was not as evident in patients who developed a second cancer in the opposite breast. This is particularly significant because radiation is less likely to be an option when cancer returns to the same breast. The authors conclude that patients who develop an invasive recurrence in the same breast as their initial DCIS may benefit from intensified and aggressive treatment.