Maria Cristina Leonardi1, Patrick Maisonneuve2, Mauro Giuseppe Mastropasqua3, Federica Cattani4, Giuseppe Fanetti5, Anna Morra1, Roberta Lazzari1, Federica Bazzani5, Mariangela Caputo5, Nicole Rotmensz2, Marianna Alessandra Gerardi1, Rosalinda Ricotti1, Viviana Enrica Galimberti6, Paolo Veronesi7, Samantha Dicuonzo8, Giuseppe Viale9, Barbara Alicja Jereczek-Fossa5, Roberto Orecchia10. 1. Division of Radiation Oncology, European Institute of Oncology, Milan, Italy. 2. Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy. 3. Division of Pathology, European Institute of Oncology, Milan, Italy. 4. Unit of Medical Physics, European Institute of Oncology, Milan, Italy. 5. Division of Radiation Oncology, European Institute of Oncology, Milan, Italy; Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy. 6. Division of Breast Surgery, European Institute of Oncology, Milan, Italy. 7. Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy; Division of Breast Surgery, European Institute of Oncology, Milan, Italy. 8. Division of Radiation Oncology, European Institute of Oncology, Milan, Italy; Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy. Electronic address: samantha.dicuonzo@ieo.it. 9. Division of Pathology, European Institute of Oncology, Milan, Italy; Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy. 10. Department of Oncology and Hemato-oncology, University of Milan, Milan, Italy; Department of Medical Imaging and Radiation Sciences, European Institute of Oncology, Milan, Italy.
Abstract
PURPOSE: To investigate the local outcome of patients after accelerated partial breast irradiation with intraoperative electrons (IORT) for invasive lobular carcinoma (ILC) compared with invasive ductal carcinoma (IDC). METHODS AND MATERIALS: From 1999 to 2007, 2173 patients were treated with breast-conserving surgery and IORT (21 Gy/1 fraction) as the sole local treatment: 252 patients with ILC (11.6%) were compared with 1921 patients with IDC in terms of local control. RESULTS: Compared with the IDC subgroup, patients with ILC had a low-risk profile and were more hormone responsive. The 5- and 10-year in-breast tumor reappearance (IBTR) rates were 5.5% and 14.4%, respectively, for the IDC group and 7.5% and 21.8%, respectively, for the ILC group (log-rank P=.03). The excess risk of IBTR associated with ILC was particularly high for small tumors (≤1 cm: hazard ratio [HR], 2.24; 95% confidence interval [CI], 1.03-4.85), elderly patients (60-69 years: HR, 2.27; 95% CI, 1.11-4.63; ≥70 years: HR, 3.28; 95% CI, 1.08-10.0), low-grade tumors (grade 1: HR, 3.50; 95% CI, 1.05-11.7), and luminal A molecular subtype (HR, 3.18; 95% CI, 1.49-6.77). Among the ILC histologic variants, no difference between classic and nonclassic subgroups was observed, although the signet ring cell and solid variants had the worst local control. CONCLUSIONS: Despite a favorable tumor profile, accelerated partial breast irradiation with IORT led to a higher incidence of IBTRs in patients with ILC compared with those with IDC. Our institutional experience emphasized the importance of the size of the irradiation field, pointing to the use of larger collimators, even when dealing with small tumors, to improve local control.
PURPOSE: To investigate the local outcome of patients after accelerated partial breast irradiation with intraoperative electrons (IORT) for invasive lobular carcinoma (ILC) compared with invasive ductal carcinoma (IDC). METHODS AND MATERIALS: From 1999 to 2007, 2173 patients were treated with breast-conserving surgery and IORT (21 Gy/1 fraction) as the sole local treatment: 252 patients with ILC (11.6%) were compared with 1921 patients with IDC in terms of local control. RESULTS: Compared with the IDC subgroup, patients with ILC had a low-risk profile and were more hormone responsive. The 5- and 10-year in-breast tumor reappearance (IBTR) rates were 5.5% and 14.4%, respectively, for the IDC group and 7.5% and 21.8%, respectively, for the ILC group (log-rank P=.03). The excess risk of IBTR associated with ILC was particularly high for small tumors (≤1 cm: hazard ratio [HR], 2.24; 95% confidence interval [CI], 1.03-4.85), elderly patients (60-69 years: HR, 2.27; 95% CI, 1.11-4.63; ≥70 years: HR, 3.28; 95% CI, 1.08-10.0), low-grade tumors (grade 1: HR, 3.50; 95% CI, 1.05-11.7), and luminal A molecular subtype (HR, 3.18; 95% CI, 1.49-6.77). Among the ILC histologic variants, no difference between classic and nonclassic subgroups was observed, although the signet ring cell and solid variants had the worst local control. CONCLUSIONS: Despite a favorable tumor profile, accelerated partial breast irradiation with IORT led to a higher incidence of IBTRs in patients with ILC compared with those with IDC. Our institutional experience emphasized the importance of the size of the irradiation field, pointing to the use of larger collimators, even when dealing with small tumors, to improve local control.
Authors: Gerd Fastner; Roland Reitsamer; Christoph Gaisberger; Markus Stana; Felix Sedlmayer Journal: Strahlenther Onkol Date: 2021-10-01 Impact factor: 3.621