Impact of molecular subtype on 1325 early-stage breast cancer patients homogeneously treated with hypofractionated radiotherapy without boost: Should the indications for radiotherapy be more personalized?

Andrei Fodor, Chiara Brombin, Paola Mangili, Fulvio Borroni, Marcella Pasetti, Roberta Tummineri, Flavia Zerbetto, Barbara Longobardi, Lucia Perna, Italo Dell'Oca, Chiara L. Deantoni, Aniko M. Deli, Anna Chiara, Sara Broggi, Roberta Castriconi, Pier Giorgio Esposito, Najla Slim, Paolo Passoni, Simone Baroni, Stefano L. VillaPaola M.V. Rancoita, Claudio Fiorino, Antonella Del Vecchio, Giampaolo Bianchini, Oreste D. Gentilini, Mariaclelia S. Di Serio, N. G. Di Muzio

Research output: Contribution to journalArticlepeer-review

Abstract

Aim: We report molecular subtype impact on 1325 early breast cancer (BCa) patients treated with whole breast hypofractionated (WBH) adjuvant forward-planned intensity modulated radiotherapy (F-IMRT) without boost. Methods and materials: From 02/2009-05/2017 1325 patients with pTis-pT3, pNx-N1aM0 BCa who underwent breast conservation surgery were treated with WBHF-IMRT in our institute, to a total dose of 40 Gy/15 fractions, without boost. Median age: 62 (interquartile range-IQR-:51.14–70.53) years. Histology: 8% in situ carcinoma (ISC), 92% invasive tumors. Molecular subtypes (invasive tumors): 49.9% Luminal A, 33.1% Luminal B Her2 negative (−), 6.2% Luminal B Her2 positive (+), 3.6% Hormone Receptor (HR)- Her2+, 7.1% Triple negative (TNBC), and 0.2% HR+. Chemotherapy (CT) was prescribed in 28% of patients, hormonal therapy in 80.3%, monoclonal antibodies (MAb) in 86.8% of Luminal B Her2+ and 97.7% of HR- Her2+ patients. Results: Median follow up was 72.43 (IQR: 44.63–104.13) months. The 5-year Kaplan-Meier estimates of local relapse-free survival (LRFS) was 97.8%, regional-(RRFS) 98.6%, loco-regional- (LRRFS) 96.9%, distant- (DRFS) 96.6%, disease-free survival (DFS) 94.8% and overall survival (OS) 95.5%. Considering molecular subtypes, 5-year LRFS was: 99.8% for Luminal A, 96.7% for Luminal B Her2-, 94.1% for Luminal B Her2+, 87.9% for HR- Her2+, 95.1% for TNBC and 99.1% for in situ carcinoma. Conclusion: While the overall estimated probability of LR within 5 years after WBHF-IMRT without boost is good (2.2%), molecular subtypes have a strong impact, despite MAb therapy in Her2+ patients, and CT for TNBC patients, and could be used as a parameter in deciding the boost prescription.

Original languageEnglish
Pages (from-to)45-54
Number of pages10
JournalBreast
Volume55
DOIs
Publication statusPublished - Feb 2021

Keywords

  • Breast cancer conservative treatment
  • Breast cancer molecular subtypes
  • Early stage breast cancer
  • Hypofractionated whole breast radiotherapy
  • Tumor bed boost

ASJC Scopus subject areas

  • Surgery

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