Outcomes of Node-positive Breast Cancer Patients Treated With Accelerated Partial Breast Irradiation Via Multicatheter Interstitial Brachytherapy: The Pooled Registry of Multicatheter Interstitial Sites (PROMIS) Experience.
To report outcomes for breast-conserving therapy using adjuvant accelerated partial breast irradiation (APBI) with interstitial multicatheter brachytherapy in node-positive compared with node-negative patients.



From 1992 to 2013, 1351 patients (1369 breast cancers) were treated with breast-conserving surgery and adjuvant APBI using interstitial multicatheter brachytherapy. A total of 907 patients (835 node negative, 59 N1a, and 13 N1mic) had >1 year of data available and nodal status information and are the subject of this analysis. Median age (range) was 59 years old (22 to 90 y). T stage was 90% T1 and ER/PR/Her2 was positive in 87%, 71%, and 7%. Mean number of axillary nodes removed was 12 (SD, 6). Cox multivariate analysis for local/regional control was performed using age, nodal stage, ER/PR/Her2 receptor status, tumor size, grade, margin, and adjuvant chemotherapy/antiestrogen therapy.



The mean (SD) follow-up was 7.5 years (4.6). The 5-year actuarial local control (95% confidence interval) in node-negative versus node-positive patients was 96.3% (94.5-97.5) versus 95.8% (87.6-98.6) (P=0.62). The 5-year actuarial regional control in node-negative versus node-positive patients was 98.5% (97.3-99.2) versus 96.7% (87.4-99.2) (P=0.33). The 5-year actuarial freedom from distant metastasis and cause-specific survival were significantly lower in node-positive versus node-negative patients at 92.3% (82.4-96.7) versus 97.8% (96.3-98.7) (P=0.006) and 91.3% (80.2-96.3) versus 98.7% (97.3-99.3) (P=0.0001). Overall survival was not significantly different. On multivariate analysis age 50 years and below, Her2 positive, positive margin status, and not receiving chemotherapy or antiestrogen therapy were associated with a higher risk of local/regional recurrence.



Patients who have had an axillary lymph node dissection and limited node-positive disease may be candidates for treatment with APBI. Further research is ultimately needed to better define specific criteria for APBI in node-positive patients.
Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA.
Mitchell
M
Kamrava
Arizona Breast Cancer Specialists, Scottsdale, AZ.
Robert R
RR
Kuske
Department of Radiation Oncology, University of Wisconsin, Madison, WI.
Bethany
B
Anderson
Department of Radiation Oncology, William Beaumont Hospital Royal Oak, MI.
Peter
P
Chen
Gamma West Cancer Services, Salt Lake City, UT.
John
J
Hayes
Arizona Breast Cancer Specialists, Scottsdale, AZ.
Coral
C
Quiet
Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA.
Pin-Chieh
PC
Wang
Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA.
Darlene
D
Veruttipong
Arizona Breast Cancer Specialists, Scottsdale, AZ.
Margaret
M
Snyder
Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA.
David J
DJ
Demanes
D000328:Adult; D001918:Brachytherapy / Q000379:methods*; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D018270:Carcinoma, Ductal, Breast / Q000473:pathology / Q000532:radiotherapy*; D018275:Carcinoma, Lobular / Q000473:pathology / Q000532:radiotherapy*; D002404:Catheterization / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008875:Middle Aged; D011379:Prognosis; D011879:Radiotherapy Dosage; D012042:Registries