Local excision alone enough for highly selected patients with low/intermediate-grade DCIS

Issue: November 25, 2009

Patients with low/intermediate-grade ductal carcinoma in situ who are rigorously evaluated and selected had an acceptably low rate of ipsilateral breast events after five years of follow-up, according to the results of a prospective trial. However, those patients with high-grade DCIS had a much higher rate of breast events, which may indicate a need for additional treatment outside of excision alone.

Lorie L. Hughes, MD, from Emory University in Atlanta, and colleagues sought to determine the risk for ipsilateral breast events in patients with DCIS who were treated with local excision but not adjuvant radiation, and identify a subgroup of patients who might be at low risk for local failure after this treatment.

“Several investigators have reported rates of local recurrence of 5% to 15% at five to 10 years in retrospective studies of selected patients treated with local excision alone with very wide margins,” the researchers wrote. “However, our study is the first large, multi-institutional prospective trial showing that rigorous mammographic and pathologic evaluation and selection criteria can yield comparable results.”

The trial was conducted from 1997 to 2002 by the ECOG and the North Central Cancer Treatment Group. It enrolled patients with either low/intermediate-grade DCIS that were 2.5 cm or smaller, or patients with high-grade DCIS that was 1 cm or smaller who had microscopic margin widths of 3 mm or wider and no residual calcifications on postoperative mammograms.

The low/intermediate-grade group had a median follow-up of 6.2 years. There were 49 ipsilateral breast events during that time: 53% were invasive and 46.9% were DCIS. Five-year ipsilateral breast event rate was 6.1%.

Patients in the high-grade group had a median follow-up of 6.7 years. During that time, there were 17 ipsilateral breast events: 35.3% were invasive and 64.7% were DCIS. The five-year ipsilateral breast event rate was 15.3%.

Jay R. Harris, MD, department of radiation oncology, Dana-Farber Cancer Institute, Boston, and Monica Morrow, MD, breast service, department of surgery, Memorial Sloan-Kettering Cancer Center, commented on these results in an accompanying editorial. They wrote that although the results were important, they are likely not practicing changing and cannot be generalized to all patients with DCIS.

“The annual hazard rate for ipsilateral breast events is fairly constant over the first 10 years after treatment in low/intermediate-grade DCIS, so one could anticipate the 10-year rate of ipsilateral breast events for the low/intermediate group to be approximately 12%, with half being invasive,” they wrote, “Experts may vary in their view of this, but our view is that longer follow-up is needed in the low/intermediate-grade group before the results should be considered practice changing.”

Furthermore, Harris and Morrow emphasized that patients on trial were “generally older than the usual median age of diagnosis of DCIS, had lesions smaller than 1 cm and had margins greater than 5 mm when evaluating the overall results,” making it difficult to assume results would be the same in the majority of patients with DCIS.

Hughes LL. J Clin Oncol. 2009;doi:10.1200/JCO/2009/24/1489.