Abstract
PurposeTo report a primary objective clinical outcome of ipsilateral breast recurrence following accelerated partial breast irradiation (APBI) in women with triple negative and other high risk breast cancer (as described in 2017 ASTRO guidelines) (i.e., age 40–49, size 2.1–3.0 cm, estrogen receptor negative and invasive lobular breast cancer). Secondary objectives of axillary and regional failure as well as overall survival are also reported.Methods and MaterialPatients from two clinical trials (NCT01185145, NCT01185132) were treated with 38.5 Gy IMRT or 3D-CRT APBI w/3.85 Gy fraction/BID fractionation for 10 fractions. Triple negative and other high risk patients (n=269) were compared to a total of 478 low risk patients which ASTRO defined as “suitable” for APBI. High risk patients, for the purpose of this study, were defined as those who possess one or more high risk criteria: triple negative (n=30), tumor size >2 cm <3 cm (n=50), HER 2+ (n=54), age range 40–50 years (n=120), ER- (n=43), and ILC histology (n=52).ResultsMedian follow up was 4.0 years for all patients. No significant difference was found for this high-risk cohort at 5 years for ipsilateral breast, or regional recurrences. Axillary recurrence was significantly adversely impacted by triple negative and ER- statuses (p=0.01, p=0.04). There were significant correlations between triple negative type and axillary recurrence on multivariate analysis (p=0.03). Overall survival for all patients was unaffected by any of the high-risk categories.ConclusionThe data from this study suggests that women possessing high risk features are at no more meaningful risk for recurrence than other patients considered to be acceptable for APBI treatment. However, the finding of axillary recurrence in patients with triple negative breast cancer does warrant a degree of caution in proceeding with accelerated partial breast irradiation technique in this patient group.
Highlights
Accelerated partial breast radiotherapy (APBI) recently has been widely accepted as an alternative breast radiotherapy option for the post-lumpectomy adjuvant management of breast cancer
The GEC-ESTRO Brachytherapy Committee have published recommended APBI clinical guidelines. These guidelines state that APBI could be offered as standard therapy to eligible patients >50 years of age who have T1 invasive ductal carcinoma with a minimum of 2 mm margins [4]
The National Comprehensive Cancer Network (NCCN) panel accepts the updated 2016 version of the ASTRO APBI guideline, which defines patients “suitable” for APBI to be the following: 1) 50 years or older with invasive ductal carcinoma (IDCA) measuring ≤2 cm (T1 disease) with negative margin widths of ≥2 mm, no lymphvascular invasion, estrogen receptor (ER) positive, and BRCA 1/2 negative or 2) screening-detected ductal carcinoma in situ (DCIS) with low/intermediate nuclear grade, and tumor size measuring ≤2.5 cm with negative margin widths of ≥3 mm [1]
Summary
Accelerated partial breast radiotherapy (APBI) recently has been widely accepted as an alternative breast radiotherapy option for the post-lumpectomy adjuvant management of breast cancer. The American Society of Radiation Oncology (ASTRO) has previously issued guidelines for patient categorization into “suitable”, “cautionary”, and “unsuitable” groups [2]. These guidelines were revised to expand the suitable category to include characteristics previously felt to be cautionary [3]. The GEC-ESTRO Brachytherapy Committee have published recommended APBI clinical guidelines. These guidelines state that APBI could be offered as standard therapy to eligible patients >50 years of age who have T1 invasive ductal carcinoma with a minimum of 2 mm margins [4]. The National Comprehensive Cancer Network (NCCN) panel accepts the updated 2016 version of the ASTRO APBI guideline, which defines patients “suitable” for APBI to be the following: 1) 50 years or older with invasive ductal carcinoma (IDCA) measuring ≤2 cm (T1 disease) with negative margin widths of ≥2 mm, no lymphvascular invasion, estrogen receptor (ER) positive, and BRCA 1/2 negative or 2) screening-detected ductal carcinoma in situ (DCIS) with low/intermediate nuclear grade, and tumor size measuring ≤2.5 cm with negative margin widths of ≥3 mm [1]
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