Breast Cancer

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TU_6_3352 - Accelerated Partial Breast Irradiation with IORT in the Management of DCIS: A Single-Institution Experience in Patient Selection and Treatment Outcomes

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Accelerated Partial Breast Irradiation with IORT in the Management of DCIS: A Single-Institution Experience in Patient Selection and Treatment Outcomes
C. Chin1,2, S. Hirji1,2, M. Onishi2,3, R. Ha4, B. Taback5, S. Feldman6, D. P. Horowitz1,2, and E. P. Connolly1,7; 1Department of Radiation Oncology, Columbia University Medical Center, New York, NY, 2New York Presbyterian Columbia Campus, New York, NY, 3Department of Medical Oncology, Columbia University Medical Center, New York, NY, 4Department of Radiology, Columbia University Medical Center, New York, NY, 5Department of Surgery, Columbia University Medical Center, New York, NY, 6Department of Breast Surgery, Montefiore Einstein Center for Cancer Care, New York, NY, 7Dept of Radiation Oncology, Columbia University Medical Center, New York, NY

Purpose/Objective(s): Intraoperative radiotherapy (IORT) in the management of ductal carcinoma in situ (DCIS) is controversial with limited supporting evidence, however, remains an attractive option given the indolent nature of DCIS. In 2016 ASTRO expanded their accelerated partial breast irradiation (APBI) consensus guidelines to include good-risk DCIS (age≥50years, screen-detected, size≤2.5cm, low-intermediate grade, margins≥3mm). Here we present our single-institution experience in the selection and treatment of DCIS using breast IORT.

Materials/Methods: We performed a retrospective review of our prospective institutional database to identify patients with biopsy-proven DCIS treated with breast IORT between 9/2013 and 2/2017. Patients received a single dose of 20Gy to the lumpectomy cavity surface at the time of surgery using targeted intraoperative radiotherapy.

Results: We identified 60 patients who underwent IORT for DCIS, one of which presented with synchronous DCIS of the bilateral breasts and received bilateral IORT. Median age was 63 years (range 44-84years). 60 (98.4%) patients presented with screen-detected disease. Median extent of disease by conventional imaging was 0.8cm (range 0.2-4.2cm). Disease grade was low-intermediate in 32 (52%) and high in 29 (48%). Based on preoperative clinical and pathologic characteristics, 21 (34%) patients were suitable according ASTRO guidelines, 36 (59%) cautionary. 4 (7%) patients were unsuitable due to lesion size however declined standard whole breast therapy. Final pathology changed group suitability in 15 (25%) patients, summarized in Table 1. 5 (8.2%) patients underwent re-excision lumpectomy for positive margins, 1 (1.6%) for close margins. 7 (11.5%) patients received adjuvant whole breast radiotherapy after either re-excision or for close margins. Of the 51 (84%) patients with hormone-receptor positive disease, 37 (73%) initiated hormonal therapy with 32 (63%) compliant at last follow-up. At a median follow-up of 2.2 years, 3 (4.9%) patients experienced ipsilateral breast tumor recurrence. Of these 3 patients, one was considered cautionary due to high grade disease. The second was cautionary based on final close margins, declining both further re-excision and hormonal therapy. Lastly, the third patient was suitable however also declined adjuvant hormonal therapy.
Pre op Patient Group Reason
# Grade Size ER negative Age Palpable
Suitable 21
Cautionary 36 28 2 8 4 1
Unsuitable 4 4
Post op Group Change # Grade Size Close Margins Positive Margins T1mi/T1
Suitable to Cautionary 3 2 2
Cautionary to Unsuitable 12 4 5 3

Conclusion: Breast IORT is an attractive cost-effective option for women with DCIS, however longer follow-up and prospective randomized evidence is necessary to help optimize patient selection. This is the goal of our current phase 2 futility study (NCT03216421), which will examine treatment outcomes and toxicity as well as investigate the utility of the Oncotype DX® Breast DCIS Score™ in the setting of APBI.

Author Disclosure: C. Chin: None. S. Hirji: None. M. Onishi: None. R. Ha: None. S. Feldman: None. D.P. Horowitz: Consultant; Champions Oncology. E.P. Connolly: Employee; Celgene. Research Grant; Eisai, Merck. Advisory Board; Eisai.

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