Body mass index in breast cancer patients treated with intra-operative electronic brachytherapy
Barbara Schwartzberg,
USA
PO-1221
Abstract
Body mass index in breast cancer patients treated with intra-operative electronic brachytherapy
Authors: Barbara Schwartzberg1, A. M. Nisar Syed2, Maen Farha3, Charles Hodge4, Craig Wengler5
1Schwartzberg Center for Minimally Invasive Breast Surgery, Surgery, Santa Rosa, California, USA; 2MemorialCare Health System, Radiation Oncology, Long Beach, California, USA; 3MedStar Good Samaritan Hospital, Surgery, Baltimore, Maryland, USA; 4Advent Health Florida Hospital, Radiation Oncology, Orlando, Florida, USA; 5Martin Health System, Surgery, Stuart, Florida, USA
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Purpose or Objective
Obesity is a known disparity for breast cancer patients (pts)
in the United States. Obese women with breast cancer have more complications from
surgery, radiation, and chemotherapy, and are at increased risk for local
recurrence. Ipsilateral breast tumor recurrence (IBTR) pt outcomes based on
body mass index (BMI) were analyzed in the IRB-approved single arm prospective
multi-institution ExBRT trial designed to determine the efficacy and outcome of
single fraction 20 Gy intra-operative radiation therapy (IORT) using Xoft
electronic brachytherapy at the time of breast conserving surgery for
early-stage breast cancer.
Material and Methods
Between May 2012–July 2018, 1200 enrolled breast cancer pts
were successfully treated per protocol with lumpectomy plus
single 20 Gy fraction IORT. Data collection and retrospective chart review included
demographics, BMI (not recorded for 1 pt), histopathology, medical therapy, IBTR,
and survival. The Exact Chi-square, 2 sided test was used for statistical
analysis.
Results
1200 pts (mean age 66 years, mean tumor size 11.7 mm, mean
BMI: 29.4) completed IORT treatment per protocol. At median 4.0-year follow-up,
there were 42 (3.5%) IBTR (original mean tumor size: 13.7 mm, mean BMI: 31.0).
Pt BMI and outcomes are shown in Table 1. Although IBTR was highest in the BMI
46-50 group, this did not reach statistical significance (p=0.0832).There was one
breast cancer-related death.
Table1. IORT treatment outcomes by BMI
| BMI | 16-20 | 21-25 | 26-30 | 31-35 | 36-40 | 41-45 | 46-50 | 50+ |
| Pt number | 59 | 308 | 391 | 250 | 110 | 51 | 23 | 7 |
| Mean BMI | 19.2 | 23.4 | 28.0 | 32.7 | 37.9 | 42.4 | 47.6 | 53.5 |
| IBTR | 0 | 13 (4.2%) | 7 (1.8%) | 14 (5.6%) | 3 (2.7%) | 2 (3.9%) | 3 (13.0%) | 0 |
| IBTR Mean BMI | N/A | 23.6 | 33.1 | 33 | 38 | 42 | 48 | N/A |
Conclusion
At median 4.0-year follow-up, 1200 breast cancer pts
successfully treated with lumpectomy plus single 20 Gy fraction IORT per
protocol were found to have an IBTR rate of 3.5% which was independent of BMI. Pts
with higher BMIs were successfully treated with breast conserving surgery
followed by IORT. Pts with BMIs of 46-50 had a high but not statistically
significant IBTR incidence.