The benefit of 18F-FDG PET/CT in the follow-up of breast cancer with positive sentinel lymph node without axillary dissection

Objectives We have just closed a randomized clinical phase III study. The OTOASOR (Optimal Treatment of the Axilla - Surgery or Radiotherapy) trial compared the results of the completion axillary lymph node dissection (ALND) and axillary nodal irradiation (ANI) without ALND in patients with early-stage breast cancer after positive sentinel lymph node biopsy (SLNB). Patients received 50 Gy ANI postoperatively without ALND. The further nodal involvement remained unknown. PET/CT has been reported recently to be a very sensitive test for restaging and follow-up of patients with breast cancer. The aim of this study was to test the sensitivity of PET/CT in the evaluation of therapeutic efficacy of the axillary nodal irradiation.

Methods Forty-five T1-2 SLNB positive patients were selected from OTOASOR trial. All patients underwent surgery and SLNB, the SLN(s) were found positive and patients received 50Gy ANI instead of completion ALND. Six months following radiotherapy patients underwent 18F-FDG PET/CT, mammography, sonography (US), or breast MRI. The findings of PET/CT were compared to the results of other imaging tests.

Results Five out of 45 patients had suspicious findings in the axillary tail on mammography combined with US. PET/CT suggested locoregional residual disease in only one patient that was confirmed by core biopsy. In the remaining four cases PET/CT reported no evidence of malignity that was confirmed by biopsy.

Conclusions Our preliminary data suggest that ANI without ALND does not increase the risk of recurrence of the sentinel positive patients. The results of our study demonstrate the benefit of 18F-FDG PET/CT in the follow-up of breast cancer patients with positive SLN without ALND