MammoSite® accelerated partial breast irradiation: A single-institution outcomes analysis with 2 years of followup

Haley, Marsha; Beriwal, Sushil; Heron, Dwight E.; Kim, Hayeon; Falk, Jeffrey; Johnson, Ronald; Mogus, Robert

doi:10.1016/j.brachy.2008.07.005

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Volume 8, Issue 1 , Pages 9-13, January 2009

MammoSite^® accelerated partial breast irradiation: A single-institution outcomes analysis with 2 years of followup

Marsha Haley
- Department of Radiation Oncology, Magee-Womens Hospital, Pittsburgh, PA
Sushil Beriwal
- Department of Radiation Oncology, Magee-Womens Hospital, Pittsburgh, PA
- Corresponding author. Department of Radiation Oncology, Magee-Womens Hospital, 300 Halket Street, Pittsburgh, PA 15213, USA. Tel.: +1-412-641-4600; fax: +1-412-641-6601.
Dwight E. Heron
- Department of Radiation Oncology, Magee-Womens Hospital, Pittsburgh, PA
Hayeon Kim
- Department of Radiation Oncology, Magee-Womens Hospital, Pittsburgh, PA
Jeffrey Falk
- Department of Surgery, Magee-Womens Hospital, Pittsburgh, PA
Ronald Johnson
- Department of Surgery, Magee-Womens Hospital, Pittsburgh, PA
Robert Mogus
- Department of Radiation Oncology, Magee-Womens Hospital, Pittsburgh, PA

Received 23 May 2008; received in revised form 23 July 2008; accepted 24 July 2008. published online 28 October 2008.

Abstract

Purpose

To provide longitudinal follow-up and assess the intermediate outcomes in breast cancer patients treated with the MammoSite^® radiation therapy system.

Methods and Material

Ninety-two patients with histologically proven stage 0-II breast cancer were treated with MammoSite^® accelerated partial breast irradiation after breast-conserving surgery. The catheter was placed at the time of surgery or postoperatively. Treatment prescription was 3.4Gy b.i.d. for a period of five days using high-dose-rate afterloading. Clinical and dosimetric parameters including dose to 90% of PTV, volume of PTV receiving 100% of dose, volume of PTV receiving 150% of dose, edited PTV, and dose homogeneity index were analyzed as variables correlating with late effects.

Results

All patients received the prescribed treatment. Seventy-seven percent of patients had intraoperative catheter placement, which was associated with a higher rate of persistent seroma (79%). The presence of seroma did not affect cosmesis. Ten patients developed telangiectasia at a median of 20.5 months. Skin dose and balloon-to-skin distance had a significant correlation with the development of telangiectasia that significantly affected cosmetic grading. The telangiectasia incidence for maximum skin dose of >100% and >125% of the prescription dose were 28% and 63%, compared with 0% (p=0.0001) and 4.2% (p=0.0001) for doses of ≤100% and ≤125%, respectively. Overall, most patients had excellent cosmetic results, and local control of disease was excellent.

Conclusions

MammoSite^® radiation therapy system demonstrates excellent local control and cosmetic outcome with extended followup. The maximum skin dose should be kept below 100% to reduce late effects on skin and improve cosmetic outcome. The persistence of seroma is higher with intraoperative placement of the catheter, and therefore postoperative placement is preferred.

Keywords: MammoSite^®, Outcomes, APBI