Targeted intraoperative radiotherapy tumour bed boost during breast-conserving surgery after neoadjuvant chemotherapy

Strahlenther Onkol. 2017 Jan;193(1):62-69. doi: 10.1007/s00066-016-1072-y. Epub 2016 Nov 17.

Abstract

Introduction: The use of targeted intraoperative radiotherapy (TARGIT-IORT) as a tumour bed boost during breast-conserving surgery (BCS) for breast cancer has been reported since 1998. We present its use in patients undergoing breast conservation following neoadjuvant therapy (NACT).

Method: In this retrospective study involving 116 patients after NACT we compared outcomes of 61 patients who received a tumour bed boost with IORT during lumpectomy versus 55 patients treated in the previous 13 months with external (EBRT) boost. All patients received whole breast radiotherapy. Local recurrence-free survival (LRFS), disease-free survival (DFS), distant disease-free survival (DDFS), breast cancer mortality (BCM), non-breast cancer mortality (NBCM) and overall mortality (OS) were compared.

Results: Median follow up was 49 months. The differences in LRFS, DFS and BCM were not statistically significant. The 5‑year Kaplan-Meier estimate of OS was significantly better by 15% with IORT: IORT 2 events (96.7%, 95%CI 87.5-99.2), EBRT 9 events (81.7%, 95%CI 67.6-90.1), hazard ratio (HR) 0.19 (0.04-0.87), log rank p = 0.016, mainly due to a reduction of 10.1% in NBCM: IORT 100%, EBRT 89.9% (77.3-95.7), HR (not calculable), log rank p = 0.015. The DDFS was as follows: IORT 3 events (95.1%, 85.5-98.4), EBRT 12 events (69.0%, 49.1-82.4), HR 0.23 (0.06-0.80), log rank p = 0.012.

Conclusion: IORT during lumpectomy after neoadjuvant chemotherapy as a tumour bed boost appears to give results that are not worse than external beam radiotherapy boost. These data give further support to the inclusion of such patients in the TARGIT-B (boost) randomised trial that is testing whether IORT boost is superior to EBRT boost.

Keywords: Breast cancer; External boost; Intraoperative radiotherapy; Neoadjuvant therapy; Tumor bed boost.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Breast Neoplasms / mortality*
  • Breast Neoplasms / therapy*
  • Chemoradiotherapy, Adjuvant / mortality*
  • Chemoradiotherapy, Adjuvant / statistics & numerical data
  • Disease-Free Survival
  • Female
  • Germany / epidemiology
  • Humans
  • Longitudinal Studies
  • Mastectomy, Segmental / mortality*
  • Mastectomy, Segmental / statistics & numerical data
  • Middle Aged
  • Neoadjuvant Therapy / mortality
  • Neoadjuvant Therapy / statistics & numerical data
  • Neoplasm Recurrence, Local / mortality*
  • Neoplasm Recurrence, Local / prevention & control
  • Prevalence
  • Radiation Dose Hypofractionation*
  • Retrospective Studies
  • Risk Factors
  • Survival Rate
  • Treatment Outcome