Cosmetic outcomes for accelerated partial breast irradiation before surgical excision of early-stage breast cancer using single-dose intraoperative radiotherapy

Abstract

Purpose: Determine cosmetic outcome and toxicity profile of intraoperative radiation delivered before tumor excision for patients with early-stage breast cancer.

Methods and materials: Patients age 48 or older with ultrasound-visible invasive ductal cancers <3 cm and clinically negative lymph nodes were eligible for treatment on this institutional review board-approved Phase II clinical trial. Treatment planning ultrasound was used to select an electron energy and cone size sufficient to cover the tumor plus a 1.5- to 2.0-cm circumferential margin laterally and a 1-cm-deep margin with the 90% isodose line. The dose was prescribed to a nominal 15 Gy and delivered using a Mobetron electron irradiator before tumor excision by segmental mastectomy. Physician- and patient-assessed cosmetic outcome and patient satisfaction were determined by questionnaire.

Results: From March 2003 to July 2007, 71 patients were treated with intraoperative radiation therapy. Of those, 56 patients were evaluable, with a median follow-up of 3.1 years (minimum 1 year). Physician and patient assessment of cosmesis was "good or excellent" (Radiation Therapy Oncology Group cosmesis scale) in 45/56 (80%) and 32/42 (76%) of all patients, respectively. Eleven patients who received additional whole breast radiation had similar rates of good or excellent cosmesis: 40/48 (83%) and 29/36 (81%), respectively). Grade 1 or 2 acute toxicities were seen in 4/71 (6%) patients. No Grade 3 or 4 toxicities or serious adverse events have been seen.

Conclusion: Intraoperative radiotherapy delivered to an in situ tumor is feasible with acceptable acute tolerance. Patient and physician assessment of the cosmetic outcome is good to excellent.

Figure 1

Patient flow diagram.

Figure 2

Treatment delivery schematic. Target tissue is exposed by retracting the skin around the electron cone. An electron energy is chosen to provide 90% coverage to a point 1 cm deep to the tumor.

Figure 3

Representative photographs of three patients who received only IORT (A and C) or IORT + WBRT (B) taken at the time of their 6 month, 1 year, and 2 year follow-up visit. Ratings shown represent physician (left) and patient (right) cosmetic outcome assessment.

Figure 4

Non-inferiority has been demonstrated by when comparing this study’s 1 and 2 year physician cosmetic assessment to the hypothesized rate of 85%. The lower bounds of the 95% confidence interval are above the ‘a prior’ set boundary of −20%.