EORTC DCIS Study Confirms Recurrence Reduction With RT

FLORENCE, Italy—Radiotherapy reduces the odds of local recurrence in women with ductal carcinoma in situ (DCIS) who have undergone breast-conserving surgery, according to 4-year follow-up evidence from a trial conducted by the European Organization for Research and Treatment of Cancer (EORTC).

These early EORTC findings, presented at the First European Breast Cancer Conference, support the results of NSABPB-17, the only other prospective randomized trial to explore outcome following conservative treatment of preinvasive breast cancer.

In the multicenter EORTC trial, more than 1,000 women who underwent local excision of lesions less than 5 cm in size were randomized to receive either external irradiation with 50 Gy over 5 weeks or no further treatment.

All study participants were under the age of 70, had good performance status, exhibited microscopic free margins, and had neither concurrent malignancies nor Paget’s disease. Two-thirds of patients in both treatment groups required only one operation, and approximately one-fifth underwent axillary dissection. Follow-up consisted of annual mammography.

Reporting on behalf of the EORTC Breast Cancer Cooperative Group, Dr. J.P. Julien, of Henri Becquerel Center, Rouen, France, said that the rate of local recurrence was 38% lower among women who had been treated with postoperative radiation (P = .005). Similar risk reductions were achieved for both invasive and noninvasive recurrences, he noted (see Table).

However, Dr. Julien emphasized, radiotherapy had no impact on the development of distant metastases or on overall survival. Likewise, the time that elapsed before the occurrence of a first event was similar in both study arms.

“We shouldn’t conclude that all patients with DCIS should have radiotherapy,” Dr. Julien cautioned. The challenge, he said, will be to develop reliable methods of identifying those women most likely to progress to invasive or metastatic disease. Central pathology review of 845 EORTC study enrollees has spotlighted a correlation between histologic features and clinical outcome, although the influence of radiotherapy on the various subgroups has yet to be analyzed.

“The risk of local recurrence, and especially the risk of invasive local recurrence, is not dependent on the grade of DCIS,” observed Dr. N. Bijker, of the Netherlands Cancer Institute, Amster-dam. “However,” she continued, “high-grade DCIS is associated with an increased risk of distant metastases and seems to be related to an increased risk of death.”

Dr. Bijker explained that these findings support the theory that the malignancy grade of invasive breast cancer sustains its preinvasive grade.