Fat necrosis in women with early-stage breast cancer treated with accelerated partial breast irradiation (APBI) using interstitial brachytherapy

Purpose: To report the incidence of clinical, pathological and radiological fat necrosis (FN) in women treated with accelerated partial breast irradiation (APBI) using interstitial brachytherapy (BRT) for early-stage breast cancer and to study certain variables associated with it.

Methods and materials: Between May 2000 and August 2008, 171 women were treated with APBI using high dose rate (HDR) BRT. Patients were treated to a dose of 34 Gy/10 fractions/1 week with two fractions/day after intraoperative/postoperative placement of catheters.

Results: At a median follow up of 48 months (SD: 28) 20 women developed FN with median time to detection being 24 months (range: 4-62 months, SD: 20). Actuarial 5 and 7 year FN rate was 18% and 23%, respectively. Grade 1 FN was seen in 4, grade 2 in 8 and grade 4 in 8 women. Additional investigations such as aspiration/biopsy were done in 9 patients. Volume of excision was the only significant factor affecting FN (p=0.04).

Conclusions: Actuarial FN rate of 18% at 5 years in our study was comparable to other reported series of FN. Median time of detection of FN was 24 months. Higher volume of excision resulted in an increased incidence of fat necrosis.