Intraoperative partial irradiation for highly selected patients with breast cancer: Results of the INTRAOBS prospective study

To evaluate our long-term experience on one-day breast intraoperative radiotherapy (IORT) given as sole radiation treatment to selected patients with breast cancer.Inclusion criteria of INTRAOBS study (prospective observational study) were: ER+ T1N0 unifocal ductal carcinoma; absence of lymphovascular invasion or of extensive intraductal component (Scarff-Bloom-Richardson grade III and HER2+++ excluded). Two different linacs were used (20Gy/1 fraction): one dedicated electron linac (October 2011), and afterwards a mobile linac (50kV photons). The primary endpoint was the local recurrence rate (=ipsilateral breast cancer recurrences number). Secondary endpoints were recurrence-free survival (RFS), overall and specific survival, cosmetic results, and patient satisfaction.Of the present pre-planned analysis for the first 200 patients (median age: 68 years; range, 59-87 years) who received IORT between January 2010 and October 2014 (median follow-up of 53.4 months). A total of 193 patients were still alive. The local recurrence rate was 2.5% (n=5). The 1- and 5-year local RFS rates were 100% and 95.2%, respectively. At 12 months post-surgery, satisfaction about IORT was excellent for 86.9% of patients. Cosmetic results were considered by patients and physicians as good or very good in 89.4% and 97.3% of cases, respectively.IORT for selected patients with breast cancer shows low recurrence rates, good cosmetic outcomes and excellent satisfaction.