Tumor size-driven dose of intraoperative radiotherapy for breast cancer: 18 Gy versus 21 Gy

Aim: To test whether a reduced total single dose of 18 Gy of intraoperative radiotherapy with electrons (IORT) may be tailored to safely treat patients in comparison with the standard dose of 21 Gy. (NCT01276938). Patients and Methods: From October 2009 to December 2011, 199 females affected by breast cancer were treated with conservative surgery and IORT with two different exclusive doses, 18 or 21 Gy. Results: The median follow-up was 91 months (16-104 months). Sixty-five patients (pT1a, pN0mic, pMx, G1-G3) received 18 Gy and 134 patients (pT1c, pN0mic, pMx, G1-G3) received 21 Gy. No significant difference in local recurrence-free survival or overall survival was detected in the 18 Gy-treated arm versus that treated with 21 Gy: 96.9% vs. 96.3%, p=0.72, and 96.9% vs. 95.5%, p=0.82, respectively at 5 years. Conclusion: The lower dose of 18 Gy achieved excellent results in terms of local toxicity and local control in early breast cancer.