Long-Term Outcomes of an International Cooperative Study of Intraoperative Radiotherapy Upfront Boost With Low Energy X-Rays in Breast Cancer

Abstract

PurposeThe purpose of this study was to assess the effectivity of upfront kilovoltage intraoperative radiotherapy (IORT) as a boost in high-risk early-stage breast cancer patients from an international pooled cohort.Materials/MethodsPatients from four centers in three different countries were retrospectively screened. Those with a minimum 1-year follow-up were included. Cumulative local (LR), regional (RR), and distant metastasis rates (DM) were analyzed. Additionally, the estimated overall survival (OS) was assessed. The Cox regression analysis was performed to identify failure predicting factors.ResultsA total of 653 patients from centers in Peru, Spain, and Germany were included. The median follow-up was 55 (12–180) months, and age was 58 (27–86) years. Clinical tumor (T) staging was T1 65.85%, T2 30.17%, and T3 3.98%. Positive margins were found in 7.9% and in-situ component in 20.06%. The median IORT dose was 20 (6–20). The median time from IORT to EBRT was 74.5 (13-364) days. An overall 3.4% (n = 22) of patients developed local recurrence at some point during follow-up. The 12-, 60-, and 120-month cumulative LR were 0.3%, 2.3%, and 7.9%, respectively. After multivariate analysis, only age <50 remained to be a significant prognostic factor for local recurrence (HR 0.19, 95% CI 0.08–0.47; p < 0.05). The 10-year estimated OS was 81.2%.ConclusionUpfront boost with IORT yields similar local control outcomes to those EBRT-based reports. Results from prospective trials, regarding toxicity, cosmesis, and effectivity are awaited to confirm these findings.

Targeted Intraoperative Radiation Therapy during Breast-Conserving Surgery for Patients with Early Stage Breast Cancer: A Phase II Single Center Prospective Trial

“…In the TARGIT-A trial, patients were assigned as per protocol to receive further EBRT when margins were <1 mm, which is not comparable to our cohort. A study by Sarria et al 17 assessing the effectivity of upfront kilovoltage IORT as a boost in high-risk ESBC for 653 patients from 4 different centers only showed significant association with age <50 years. In this study close margins (<2 mm) were not associated with increased LR.…”

Experience with intraoperative radiation therapy in an urban cancer center

“…Further follow-up is needed to determine the long-term IBTR, and OS rates of patients in our registry. The concept of IORT using low kV-X rays as a boost compared to an EBRT boost was studied retrospectively and IORT boost seems to yield similar local control rates as EBRT boost [ 25 , 26 ]. This is being studied prospectively in the ongoing multicenter randomized controlled TARGIT-B trial (ClinicalTrials.gov Identifier: NCT01792726).…”

The Efficacy of Low-Kilovoltage X-Rays Intraoperative Radiation as Boost for Breast Cancer: A Systematic Review and Meta-Analysis

“…Te PubMed search string generated 119 results. After examining the inclusion and exclusion criteria, eleven retrospective studies (11 cohort studies and 1 case-control study) were considered eligible to be included [7,[14][15][16][17][18][19][20][21][22][23][24] (Figure 1). No risk of bias was found due to missing results or each synthesis.…”