Local control following single-dose intraoperative radiotherapy prior to surgical excision of early-stage breast cancer.
BACKGROUND
Multiple partial breast radiotherapy techniques are available. We have previously presented the technical details of our procedure of delivering partial breast irradiation with a single fraction of intraoperative radiotherapy (IORT) targeting the tumor in situ prior to partial mastectomy. This study details our completed, single-institution trial.


METHODS
An IRB-approved, DSMB-monitored phase II trial was performed with the following inclusion criteria: women age ≥48, ultrasound-visible invasive ductal cancers <3 cm, clinically negative axillary nodes. IORT was delivered using mobile electron irradiator, at least a 1.5-cm radial and 1-cm deep margin; patients received 15 Gy and immediately underwent partial mastectomy. Ipsilateral breast recurrence was classified as true/marginal, elsewhere in the breast or nodal basin. Kaplan-Meier methods were used to estimate survival functions and exact 95% confidence intervals are reported.


RESULTS
Between 2003 and 2007, 71 women underwent IORT (median follow-up: 3.5 years). For patients with tumor-involved or close margins, additional therapy was required: 7 patients, total mastectomy; 11, whole breast radiation. Four women experienced invasive ipsilateral breast failures (1 new primary, 3 margin recurrences) for a 3-year local control rate of 49 of 53 (94.8%; 95% confidence interval 92.4% [95% CI] 84.2–98.3%), actuarial three-year in breast recurrence was 8% (95% CI 2–18%), and breast cancer-specific survival was 100%.


CONCLUSIONS
Intraoperative radiotherapy delivered to an in situ tumor is feasible, but our local control rate at 3.5 years is concerning. Possible changes to this technique to improve local control rates include better preoperative imaging (MRI), routine intraoperative ultrasound, and improved IORT delivery (larger cone, increased dose).
Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Randall J
RJ
Kimple
Nancy
N
Klauber-DeMore
Cherie M
CM
Kuzmiak
Dag
D
Pavic
Jun
J
Lian
Chad A
CA
Livasy
WingKeung M
WM
Chiu
Dominic T
DT
Moore
Carolyn I
CI
Sartor
David W
DW
Ollila
D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007430:Intraoperative Care; D008408:Mastectomy; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery*; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant; D015996:Survival Rate; D016896:Treatment Outcome