Outcomes After Accelerated Partial Breast Irradiation in Women With Triple Negative Subtype and Other “High Risk” Variables Categorized as Cautionary in The ASTRO Guidelines

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.

Concurrent chemotherapy with partial breast irradiation in triple negative breast cancer patients may improve disease control compared with sequential therapy

“…In contrast, Goulding et al. ( 30 ) analyzed patients on two prospective APBI trials that were treated with external beam RT, and when specifically looking at TNBC and other “high risk” patients compared with “suitable” patients, TNBC was not associated with higher in-breast recurrence risk, with no local recurrences occurring in this cohort.…”

Intraoperative electron radiotherapy in early invasive ductal breast cancer: 6-year median follow-up results of a prospective monocentric registry

“…It should be noted that the post-hoc analyses used in the ELIOT trial to try to find factors associated with IBTR were just exploratory in nature, as were those underpinning our study. Moreover, factors found to be linked to IBTR are very inconsistent across different APBI trials with some finding no link between molecular types or grades and IBTR [ 16 , 49 ]. Thus, guidelines based on these analyses should always be prospectively assessed.…”