Comparison of mammographic findings after intraoperative radiotherapy or external beam whole breast radiotherapy.

BACKGROUND: The TARGIT (TARGeted Intraoperative Radiotherapy) trial was designed to compare local recurrence and complication rates in breast cancer patients, prospectively randomised to either EBRT (external beam whole breast radiotherapy) or a single dose of IORT (intraoperative radiotherapy). The aim of our study was to compare follow-up mammographic findings, ultrasound and biopsy rates in each group. METHODS: Follow-up imaging and breast biopsies of women from one centre participating in the TARGIT-A trial were independently reviewed by two radiologists blinded to the radiotherapy treatment received. RESULTS: The cohort consisted of 141 patients (EBRT n = 80/IORT n = 61). There was no significant difference in the patient or disease characteristics of the two groups. The number of follow-up mammograms and length of follow-up was similar (EBRT/IORT n = 2.0/2.4; 4.3yr/5.1yr; p = 0.386 χ(2) test). There were no significant differences in mammographic scar or calcification appearances of the post-operative site. Generalised increase in breast density and skin thickening were more common in the EBRT compared to the IORT group (p = 0.002; p = 0.030, χ(2) test respectively). A trend towards additional ultrasound at follow-up was observed in the IORT group (15 of 61 [24.6%] versus 11 of 80 [13.8%]), however this was not statistically significant (p = 0.100 χ(2) test). No disease recurrence was demonstrated on any of the breast biopsies taken. Only one biopsy was reported as fat necrosis in the IORT group. CONCLUSIONS: Mammographic changes were more common following EBRT, although more additional follow-up ultrasounds were performed in the IORT group. IORT is not detrimental to subsequent radiological follow up.