18F-FDG PET complemented with sentinel lymph node biopsy in the detection of axillary involvement in breast cancer.

Aim: The presence of axillary involvement is the most important prognostic factor in breast cancer. This study analysis the value of 18F-FDG PET in the detection of the lymph node status.
Methods: This study includes 200 breast cancer patients. The PET scans were obtained after the injection of 370 MBq of 18F-FDG; the breast areas, axillary, supraclavicular and internal mammary lymph node chains were evaluated. In a subgroup of 100 patients the PET-FDG scan was complemented with the study of the sentinel node (SN) in those cases which did not demonstrate pathological lymph node uptake. The standardized uptake value (SUV) was related to the tumour characteristics of size, histological type, axillary status and histological grading.
Results: The sensitivity and specificity of PET-FDG in the detection of axillary involvement was 84.1 and 97.8%, respectively. Seventeen false negative cases were obtained, and were associated with low SUV in the mammary tumour. In 15 cases the PET-FDG scans revealed pathological uptake foci that suggested involvement of the internal mammary chain.
Conclusions: The PET-FDG avoids routine SN study in those cases presenting axillary uptake, but it must be complemented by sentinel node study in those cases without pathological uptake. The association of PET-FDG and SN improves the sensitivity in the detection of axillary involvement. Its sensitivity and specificity in the analysis of axillary status can be extended to the evaluation of the internal mammary chain.