Haitham M. Ahmed, Presenter: Nothing to Disclose

Pamela J. Dipiro MD, Abstract Co-Author: Nothing to Disclose

Phillip M. Devlin MD, FACR, Abstract Co-Author: Nothing to Disclose

Jennifer R. Bellon MD, Abstract Co-Author: Nothing to Disclose

To describe the mammographic appearance of early stage, low-risk breast cancer in patients who have received accelerated partial breast irradiation (APBI) with MammoSite® intracavitary brachytherapy.

We conducted a retrospective review of 22 patients who underwent APBI with MammoSite® brachytherapy at the Brigham & Women’s Hospital from October 2003 to March 2007. All patients received 32 Gy (in 8 fractions) or 34 Gy (in 10 fractions) prescribed to 1 cm from the balloon surface, and had a minimum of two follow-up mammograms. Distortion in all post-radiation mammograms was assessed by two attending physicians (PJD and JRB), and categorized as mild, moderate, or severe. Chart records of any patient complaints, post-radiation complications, and further procedures were reviewed and correlated with mammogram readings.

The 22 patients had a total of 92 mammograms over a median follow-up period of 46 months (range 22 – 58 months). Mean age for patients at time of brachytherapy was 63 years (range 47 – 81). One patient died of metastatic disease with no evidence of local recurrence. No patients had any ipsilateral breast recurrence. Of the 22 patients, four developed fat necrosis, two developed seroma, and two developed both fat necrosis and seroma at the lumpectomy site. Fat necrosis caused relatively decreased imaging density at the lumpectomy site compared to the rest of the breast, while seroma caused increased density, making assessment of mammographic distortion infeasible. Of the remaining 14 patients, one developed rapid and relatively severe distortion while two patients developed only mild distortion throughout follow-up. The 11 remaining patients developed moderate distortion after a median of 19 months, with a plateau in distortion thereafter. Two patients showed evidence of improving distortion after 3 years.

Patients treated with MammoSite® developed peak distortion by 1.5 years following APBI, with a plateau in distortion thereafter. This may be earlier than what is typically seen following conventionally fractionated whole breast radiation. Care should be taken to avoid unnecessary biopsy in this low risk population.

To appreciate the appearance and time course of mammographic distortion resulting from lumpectomy and MammoSite® so as to avoid unnecessary biopsies in this relatively low-risk population.

Ahmed, H, Dipiro, P, Devlin, P, Bellon, J, Mammographic Appearance after Accelerated Partial Breast Irradiation.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8009271.html