Breast-Conserving Therapy an Option With Multiple Breast Lesions

By Leah Lawrence - Last Updated: December 20, 2022

Breast-conserving therapy (BCT) may be a viable treatment option for some patients with multiple ipsilateral breast cancer (MIBC), according to results of the Z1102 trial presented at the 2022 San Antonio Breast Cancer Symposium.

“Most patients who present with two or three sites of cancer in one breast are recommended to undergo a mastectomy, as historical studies showed high local recurrence rates in patients who underwent breast-conserving therapy consisting of lumpectomy and radiation therapy,” explained Judy C. Boughey, MD, the W.H. Odell Professor of Individualized Medicine and chair of the Division of Breast and Melanoma Surgical Oncology at the Mayo Clinic. “Advances in imaging techniques have led to greater detection of additional breast tumors, leading to more patients undergoing mastectomy who otherwise may have preferred breast-conserving therapy.”

The Z1102 trial was designed to evaluate outcomes using BCT among patients with MIBC. The trial included 204 evaluable women aged 40 or older with 2 or 3 foci of breast cancer and disease limited to two quadrants of the breast. Patients were treated with lumpectomy followed by whole breast radiation with boost to all lumpectomy beds.

Median follow-up of alive patients was 66.4 months. During that time, six patients developed local recurrence. The estimated cumulative incidence of local recurrence was 3.1% at 5 years.

There was no regional recurrence. Five patients had distant recurrence, and 5 patients developed contralateral breast cancer. There were 3 new non-breast cancer primaries, and 8 patients died (1 from breast cancer).

It is important to note that, initially, all patients were required to have a preoperative mammogram and breast MRI, but these were subsequently made optional. The rate of local recurrence was greater among the 15 patients who did not undergo a pre-surgical breast MRI compared with the 189 patients who underwent this imaging (22.6% vs 1.7%). Boughey noted that this may have been due to greater detection of disease sites prior to surgery in patients who underwent breast MRI, potentially allowing for more thorough resection.

Boughey JC, Rosenkranz KM, Ballman KV, et al. Impact of breast conservation therapy on local recurrence in patients with multiple ipsilateral breast cancer – results from ACOSOG Z11102 (Alliance). Abstract GS4-01. Presented at 2022 San Antonio Breast Cancer Symposium, San Antonio, Texas.