Salvage brachytherapy for second ipsilateral breast tumor event: Relating dosimetric analysis to late side effects

Mohamed Abdul-Latih; Jocelyn Gal; Renaud Schiappa; Yassine Rizzi; Mathieu Gautier; Jean-Michel Hannoun-Levi

doi:10.1016/j.brachy.2023.12.005

Salvage brachytherapy for second ipsilateral breast tumor event: Relating dosimetric analysis to late side effects

Brachytherapy. 2024 Feb 20:S1538-4721(24)00004-7. doi: 10.1016/j.brachy.2023.12.005. Online ahead of print.

Authors

Mohamed Abdul-Latih¹, Jocelyn Gal², Renaud Schiappa², Yassine Rizzi³, Mathieu Gautier³, Jean-Michel Hannoun-Levi⁴

Affiliations

¹ Department of Radiotherapy, Mount Vernon Cancer Centre, Northwood, United Kingdom.
² Biostatistic Unit, Antoine Lacassagne Cancer Center, University of Cote d'Azur, Nice, France.
³ Department of Radiotherapy, Antoine Lacassagne Cancer Center, University of Cote d'Azur, Nice, France.
⁴ Department of Radiotherapy, Antoine Lacassagne Cancer Center, University of Cote d'Azur, Nice, France. Electronic address: jean-michel.hannoun-levi@nice.unicancer.fr.

PMID: 38383205
DOI: 10.1016/j.brachy.2023.12.005

Abstract

Purpose: For second ipsilateral breast tumor event (2ndIBTE), conservative treatment (CT) involving wide local excision plus accelerated partial breast reirradiation (APBrI) is increasingly used as an alternative to mastectomy. This study investigates the impact of APBrI technique and multicatheter interstitial high dose-rate brachytherapy (MIB) dosimetry parameters on toxicity and survival in patients with 2ndIBTE.

Materials-methods: Data from patients with 2ndIBTE treated with CT, were analyzed. Inclusion criteria specified 2ndIBTE occurring at least one year after 1st CT for primary breast cancer. Treatment details and dosimetry parameters were recorded. Primary endpoint was late toxicity. Secondary endpoints were late toxicity prognostic factors analysis and oncological outcome.

Results: From 07/2005 and 07/2023, 201 patients (pts) received 2nd CT. With a median follow-up of 49.6 months (44.9-59.5), tumor size was less than 2 cm (88.1%), with estrogen receptor positive (92.7%). Patients were low (63.7%) or intermediate (29.8%) GEC-ESTRO APBI risk classification. Late toxicities were observed in 34.8% (G1 52.3%, G2 40.7%). Cutaneous fibrosis was the most common toxicity. Cosmetic outcomes were excellent in 64.1%. Dosimetry analysis revealed positive correlations between complications and absolute volumes of CTV, V100, V150, and V200. Volumes requiring higher needle number and lower DNR resulted in fewer complications. 5-year disease-free and overall survival were 88% and 95% respectively.

Conclusion: Second CT for 2ndIBTE showed favorable oncological outcomes and survival rates. Complications were correlated with specific dosimetric parameters, emphasizing the importance of tailored treatment planning. This study provides valuable insights in risk stratification and MIB optimization for APBrI.

Keywords: Brachytherapy; Breast cancer; Conservative treatment; Dose constraints; Late complications; Local recurrence.