Intraoperative radiotherapy for breast cancer: its perceived simplicity.

Over one-quarter of a million cases of breast cancer are diagnosed in the United States each year, many of which are early stage.The radiotherapeutic options after breast-conserving surgery in early-stage breast cancer are evolving quickly, with a focus on minimizing treatment volume, toxicity, and treatment duration. One such emerging option is intraoperative radiotherapy (IORT), administered either as a single fraction or as a boost.With many centers seeking to adopt such technology, there are licensing, proctoring, staffing, technical support, and reimbursement issues that need to be considered. We have reviewed the current international experience and describe one community cancer center's experience with initiating an IORT breast cancer program.

Recurrence rates for patients with early-stage breast cancer treated with IOERT at a community hospital per the ASTRO consensus statement for APBI.

PURPOSE: To report the recurrence rates after single-fraction intraoperative electron radiotherapy (IOERT) in patients with early-stage breast cancer treated on a single institution prospective Phase I/II protocol at a community hospital. Results were retrospectively analyzed according to suitability criteria from the updated American Society for Radiation Oncology (ASTRO) consensus statement for accelerated partial breast irradiation (APBI). METHODS AND MATERIALS: Patients over 40 years with early-stage invasive or in situ breast cancer (<2.5 cm and node negative) were enrolled. IOERT 2100 cGy was delivered during breast conservation surgery, and patients were followed up for a median of 3 years (0.8-6.5 years) to determine toxicity and recurrence rates. RESULTS: Single-fraction IOERT was performed in 215 cases (6 bilateral treatments, 196 patients) with 13 patients receiving whole-breast radiation (WBR) after IOERT for adverse pathologic features. Of 202 cases of IOERT without WBR, 89 patients experienced an ipsilateral breast tumor recurrence (IBTR) giving a cumulative incidence of 3.96%. When the ASTRO APBI suitability criteria were applied, the IBTR rate was significantly lower for suitable patients vs. cautionary or unsuitable patients (1.6% vs. 3.4% vs. 21.0%, p = 0.0002). 3-year progression-free survival after IOERT alone was 93.4%. For patients who received standard WBR (4500-5040 cGy) after IOERT, no Grade 3 or 4 toxicities (acute or late) occurred and all patients are disease-free. CONCLUSIONS: Single-fraction IOERT results in a low rate of IBTR when strictly adhering to ASTRO criteria for APBI suitability. Standard dose WBR for unfavorable pathologic results after 2100 cGy IOERT is well tolerated.

A prospective phase I comparison of toxicity and cosmesis outcomes of single-fraction IORT and hypofractionated radiotherapy with IORT boost in early-stage breast cancer.

PURPOSE: Radiation therapy is proven to reduce local recurrence in patients with early-stage breast cancer. To reduce toxicity, treatment time, and improve accuracy, intraoperative radiation therapy was used as definitive treatment or as a boost. The study's objective was to compare the short-term toxicity and cosmesis of single-fraction (SF) IORT and hypofractionated radiotherapy with IORT boost (HfB) given as definitive treatment. METHODS AND MATERIALS: Between March 2011 and December 2013, 57 patients aged 45-91 years and 24 patients aged 43-83 years (total n = 81) with Stage 0-II were treated with SF or HfB (Mobetron, IntraOp Medical, Sunnyvale, CA). For SF treatment, 21 Gy was delivered using 4.5-6 cm applicators with electron energies from 6 to 12 MeV. For HfB, an intraoperative boost of 10 Gy was delivered using 4-7 cm applicators with energies from 4 to 12 MeV followed by whole-breast radiation with 40.5 Gy over 15 fractions. Toxicity was assessed at 2 weeks, 6 months, and 12 months per Radiation Therapy Oncology Group acute skin toxicity criteria and cosmesis. RESULTS: At 12 months, SF and HfB were well tolerated by all patients with no Grade 3+ toxicity. At 1 year, Grade-2 toxicity was resolved. Ninety-eight percent of SF patients and ninety percent of HfB patients had 0-1 grade toxicity. In the SF and HfB groups, 100% of patients had excellent or good cosmesis at 12-month followup interval. The SF exhibited a more favorable cosmesis with a higher percentage of excellent scores compared with HfB (80.4% vs. 45%; p = 0.0033). CONCLUSIONS: After breast conservation surgery, SF or HfB may be an option for patients with early-stage breast cancer compared to conventional external beam radiotherapy.

Intraoperative electron radiotherapy boost as a component of adjuvant radiation for breast cancer in the community setting.

To reduce toxicity/treatment time and improve accuracy, intraoperative electron radiotherapy (IOERT) was used as an alternative to electron beam radiation therapy boost. Primary objective was to determine feasibility and acute toxicity. From August 2009 to June 2011, 50 patients (age 32 to 76 years) with in situ or invasive breast cancer (Stage 0 to IIIA) were treated. Toxicity assessed according to standard National Cancer Institute scales. Median tumor size was 20 mm (range, 6 to 80 mm) with 43 infiltrating ductal, two infiltrating lobular, and five ductal in situ carcinoma. A single 10-Gy fraction boost was given to the tumor bed after resection followed by whole-breast radiotherapy. After IOERT, three patients required completion axillary lymph node dissection, eight had reexcision resulting from positive margins, and four opted for completion mastectomy. The median follow-up was 10 months (range, 2 to 24 months). Ten patients had Grade 1 and one reported Grade 2 breast pain 2 weeks after IOERT; all resolved at 6 weeks. Two patients had delay in wound healing, but none developed a wound infection. Three patients reported symptomatic fat necrosis. No other toxicities were reported. IOERT resulted in a reduction in treatment time, was not associated with additional toxicity or change in the acute toxicity profile, and is a feasible treatment option in a community hospital setting.