Hypothesis: The current standard treatment for early breast cancer includes conservative surgery followed by entire breast radiotherapy (RT). Recent study findings show that most local recurrences are in the scar tissue area suggesting that whole-breast RT may not always be necessary. If the volume of breast tissue to be irradiated is limited, RT may be performed intraoperatively. Intraoperative RT delivered with electrons at the total isodose of 2100 rad (21 Gy) could in principle substitute the currently used radiation course of external RT after breast-conserving surgery in selected cases. Patients and Methods: We report our findings on intraoperative RT using a specially designed mobile linear accelerator delivering 4 energy levels of electrons (3, 5, 7, and 9 MeV) via a head maneuvered by a robot arm. We applied this technique to 237 patients with breast cancer (mean age, 59 years; age range, 33-80 years) with tumors smaller than 2 cm in maximum diameter (T1); most underwent wide resection and an axillary sentinel node biopsy. Results: After a median follow-up of 19 months (range, 7-33 months), the rate of posttreatment complications is very low. Four patients (1.7%) developed breast fibrosis-mild in 3 patients and severe in 1 patient-that resolved in 24 months. Three patients (1.4%) developed ipsilateral breast cancer-2 (1.0%) contralateral breast cancer, 1 (0.5%) supraclavicular node metastasis, and 1 (0.5%) distant metastases. Conclusions: Intraoperative RT with electron beams reduces irradiation to the skin, subcutaneous tissue, and contralateral breast and lung. It appears to be a promising method for irradiating conservatively treated breasts and it avoids the long period of postoperative RT that may not be easily accessible to all patients.
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