Multi-lumen Breast Brachytherapy in Patients With 5 mm or Less Balloon Surface-Skin Distance (BSD) Using the Contura™ Brachytherapy Catheter

Abstract

Purpose: To evaluate the toxicity of multi-lumen breast brachytherapy in patients with 5 mm or less balloon surface-skin distance (BSD) treated with the Contura™ catheter. Materials and Methods: From September, 2008 through February, 2010 a total of 411 patients with early stage breast cancer (stages 0, I, IIA) were treated with multi-lumen HDR brachytherapy for definitive APBI using the Contura™ brachytherapy catheter. Of those patients 92 had a balloon surface-skin distance (BSD) of 5 mm or less, and had at least 6 months clinical followup. All patients were status post breast conserving surgery and met the ABS APBI guidelines for treatment eligibility. All patients received 34 Gy in ten fractions bid over 5 days, with the maximum skin dose restricted to 145% of the prescribed dose or less. Varian Brachyvision was used for 3-D conformal HDR treatment planning. CT image evaluation and DVH analyses was performed to investigate and compare the PTV_EVAL (cc) defined as a 1 cm expansion from the anterior surface of the device modified to 5 mm from the skin surface and not extending into the chest wall; BSD (mm) defined as the distance from the closest point on the balloon to the closet point on the skin surface; maximum skin dose (% and cGy); the volume of breast tissue (cc) receiving 150% and 200% of the prescription dose (V150, V200). Patient toxicity was evaluated at one week, one month and 6 months following brachytherapy including; skin reaction (RTOG Acute Radiation Morbidity Scoring Criteria), pigmentation, telangiectasia, pain, fat necrosis, symptomatic seroma. Results: The mean BSD was 3.7 mm, with a range of 1–5 mm. The mean maximum skin dose was 4508 cGy. The mean V150 was 21 cc and the V200 was 4.7 cc. The mean PTV_EVAL V90 was 93.7 %. 49 % of patients had skin reaction, including at 1 week; 47 % Grade 1, 0% Grade 2 or 3. At 1 month; 31% Grade 1, 14% Grade 2 and 0% Grade 3. At 6 months; 2% Grade 1, 2% Grade 2 and 0% Grade 3. 6.5 % developed pigmentation changes (hypo or hyper). 5.4% developed telangiectasias, 9.7% reported pain. No patients had fat necrosis, and 15.2 % had a symptomatic seroma. 1 patient had wound dehiscence (maxium skin dose 4195 cGy, 123.4% of prescribed dose) at 1 week which was healed following closure at the 1 month followup. Patients that experienced toxicity had no difference in BSD (3.6 vs 3.9 mm) or in the maximum skin dose (132.6 % vs. 132.6 %) compared to those that did not experience toxicity. Conclusions: Breast brachytherapy in patients with 5 mm or less BSD (balloon surface-skin distance) has acceptable toxicity with proper planning using the Contura™ multi-lumen catheter. Careful attention to maximum skin dose must be used, and we recommend not exceeding 145 % (4930 cGy) of the prescribed dose.