Introduction:

Intra-operative radiotherapy (IORT) is increasingly being used for the treatment of low risk breast cancer. In the randomized TARGIT trial, late toxicity was not different between patients treated with IORT and external beam radiotherapy. Early toxicity of IORT has not been fully characterized.

Methods:

IORT with one dose of 20 Gy using the Intrabeam© device has been offered as an alternative to standard treatment as part of a single center prospective single arm trial. Patients over 60 years with clinically node negative, < 2 cm invasive duct carcinomas were eligible. Patients aged 50-60 years, patients with tumors 2-3.5 cm and patients with invasive lobular carcinomas were treated with IORT if they were not candidates for standard treatment.

For the present study information regarding complications occurring within the first year after surgery was analyzed. Patients treated between 2006 and 2012 were included in this analysis.

Results:

393 patients were treated from 2006 – 2012. 4 were lost to follow up. Median age was 70 years (55-90) and median clinical tumor size was 1.2 cm (5-30).

102 patients (26.2%) had a complication. Infections were most frequent. Misdiagnosis of radiation dermatitis as infection in some cases cannot be excluded. Clinically meaningful seromas occurred in 10.2% of patient and 8.2% had a wound dehiscence, possibly related to rupture of pre-existing seromas.

Table 1

Complication type N (%) N with grade 3 (%) N with grade 4 (%) median time to recovery (range) 
Infection 42 (11) 3 (3.3)   0.62 (0.1 - 3.8) 
Seroma 40 (10.2)     13.2 (0.3-50) 
Wound dehiscence 33 (8.5) 2 (0.5)   5.8 (0.36-15.3) 
Bleeding 11 (2.8) 3 (0.8)     
Skin necrosis 2 (0.5)   2 (0.5) 3.88 (3.45-4) 
Complication type N (%) N with grade 3 (%) N with grade 4 (%) median time to recovery (range) 
Infection 42 (11) 3 (3.3)   0.62 (0.1 - 3.8) 
Seroma 40 (10.2)     13.2 (0.3-50) 
Wound dehiscence 33 (8.5) 2 (0.5)   5.8 (0.36-15.3) 
Bleeding 11 (2.8) 3 (0.8)     
Skin necrosis 2 (0.5)   2 (0.5) 3.88 (3.45-4) 

frequency, severity and time to recovery of acute complications of IORT.

18 patients (4.6%) had a grade 3 complication. 2 patients (0.5%) had grade 4 radiation induced skin necrosis of small size and both resolved within 4 months. All other complications resolved completely (table 1). Risk factors for complications in this cohort will also be presented.

Conclusions:

Intra-operative radiotherapy was associated with a relatively high rate of clinically meaningful seromas and wound dehiscence and rare small size skin necrosis. Most complications were mild – moderate. 5% of patients experienced grade 3 or 4 complications, and all resolved completely. Further study of the factors predisposing to severe complications is warranted.

Citation Format: Ayelet Shai, Maoz Zur, Michelle Leviov, Arie Bitterman, Shiloni Eitan, Mariana Steiner. Short term toxicity of intra-operative radiotherapy for patients with breast cancer treated at a single center [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P1-15-13.