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 χ² 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, χ² 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 χ² 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.