CAN WOMEN WHO HAVE HAD DUCTAL CARCINOMA IN SITU COMPLETELY EXCISED BY CORE BIOPSY AVOID ADDITIONAL THERAPY?
Editorial comment: Even though this article was published in 2017 the editors felt that a review would be worthwhile given that DCIS is continuing to become more commonly diagnosed and that needle biopsies have continued to increase in diameter. Consequently, patients who have had DCIS completely removed by core biopsy is a more common reality. This article published in the Annals of Surgical Oncology by Muhsen et al. from Memorial Sloan-Kettering Cancer Center serves as additional evidence-based guidance on the care of this conundrum.
The authors defined DCIS diagnosed by core biopsy with no residual disease on surgical excision, as minimal-volume DCIS (mDCIS). This circumstance has become more common as mDCIS is becoming much more frequent, accounting for approximately 20% of all newly diagnosed cancers in the US. In the 11 years beginning in 1990, 290 cases of mDCIS were identified at Memorial Sloan-Kettering and constituted the study population. Approximately 72% of this study group did not receive radiation therapy (210 patients). Those who did receive radiation or adjuvant endocrine therapy were more likely to have intermediate-or high-grade DCIS.
The median follow-up of 6.8 years. And ipsilateral breast event occurred in 25 (8.6%) of the patient’s eight of which had invasive cancer in 17 had DCIS. The median time to a breast event was over six years. In the 80 patients undergoing radiation therapy three had ipsilateral breast event (3.75%) all of which were DCIS.
For the entire study group with mDCIS the Kaplan-Meier ipsilateral breast events were 4.3% at five years and 12.3% at 10 years. Interestingly nuclear grade and age were not associated with ipsilateral breast events. As noted, those that receive radiation therapy trended toward a lower risk of ipsilateral breast events with a 10-year rate of 6.5% compared to 14.7% for those not receiving radiation (see graph). Only a small group of 47 women received endocrine therapy and the rate of ipsilateral breast events was not significantly lower in this small group. Nineteen women received both radiation and endocrine therapy, none of which experienced an ipsilateral breast event. In women not receiving radiation of 5- and 10-year rates of ipsilateral breast events were 4.3% and 13.9% for low-grade lesions and 5.8% and 16.1% for intermediate/high-grade mDCIS.
When considering the entire group of women with mDCIS the incidence of ipsilateral breast events was higher than that of contralateral breast events. This is also applicable to women not receiving radiation. However, among women receiving radiation ipsilateral breast events were less frequent than that occurring in the contralateral breast. Endocrine therapy reduced the risk of ipsilateral and contralateral events.
Entering into this study the authors hypothesized that patients with mDCIS who underwent breast conserving surgery and no adjuvant therapy would have an extremely low risk of local recurrence such that the risk of breast events in the ipsilateral and contralateral breast would be similar. This study did not support the authors’ hypothesis. The authors noted that the significant rate of ipsilateral breast events observed in this patient population suggests that any volume of DCIS in the breast should be considered clinically relevant.