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?. (February 2021)

• Record Type: Journal Article
• Authors: Fodor, Andrei; Brombin, Chiara; Mangili, Paola; Borroni, Fulvio; Pasetti, Marcella; Tummineri, Roberta; Zerbetto, Flavia; Longobardi, Barbara; Perna, Lucia; Dell'Oca, Italo; Deantoni, Chiara L.; Deli, Aniko M.; Chiara, Anna; Broggi, Sara; Castriconi, Roberta; Esposito, Pier Giorgio; Slim, Najla; Passoni, Paolo; Baroni, Simone; Villa, Stefano L.; Rancoita, Paola M.V.; Fiorino, Claudio; Del Vecchio, Antonella; Bianchini, Giampaolo; Gentilini, Oreste D.; Di Serio, Mariaclelia S.; Di Muzio, N.G.
• Is Part Of: Breast. Volume 55(2021)
• Page Start: 45
• Page End: 54
• Publication Date: 2021-02
• Subjects: Early stage breast cancer -- Breast cancer conservative treatment -- Hypofractionated whole breast radiotherapy -- Tumor bed boost -- Breast cancer molecular subtypes; Breast -- Diseases -- Periodicals; Breast -- Tumors -- Periodicals; Breast -- Periodicals; Electronic journals; Periodicals; 616
• DOI: 10.1016/j.breast.2020.12.004
• Languages: English
• ISSNs: 0960-9776

Abstract

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. Highlights: Hypofractionated three-weeks radiotherapy ensures good local control whitout boost. In 1325 early stage breast cancers 5-year local relapse without boost was 2.2%. Molecular subtypes have a strong impact on estimated probability of local relapse. 5-year local control (LC) was 99.8% for Luminal A vs 87.9% for HR- Her2+. 5-year LC was 96.7% for Luminal B Her2-, 94.1% for Luminal B Her2+, 95.1% for TNBC.