The comparison of FDG-PET imaging findings for detecting axillary lymphatic metastasis to sentinal node based biopsy results

Abstract

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Objectives: Axillary lymph node metastasis is the most important factor in planning the type of surgery, subsequent administration of adjuvant chemotherapy and radiation treatment. Although a histological examination of the sentinel lymph node (SLN) is frequently employed for this purpose, this approach has certain limitations. The aim of this study was to determine whether FDG-PET imaging when positive could obviate the necessity for sentinel lymph node biopsy for complete axillary node dissection in patients with breast cancer.

Methods: A total of 200 patients with a newly diagnosis of breast cancer were recruited for the present study. Age range was from 32 to 78 years with a mean of 52.4 years. All patients underwent whole body FDG-PET scan approximately 60 minutes after the intravenous administration of FDG (5.2 Mbq / kg of body weight) before SLN biopsy and surgery. PET results were compared with those of the surgical pathology findings.

Results: Among 200 patients, 169 patients underwent only SLN biopsy and 13 underwent SLN biopsy plus partial and/or complete axillary dissection during surgery. Histopathology of lymph nodes was available in 182 patients for statistical analysis. Among 182 patients, 70 patients had pathologically proven axillary lymph node metastasis. PET findings were positive in 51 (28 %) and negative in 131 (72%) patients. PET results were true positive in 35 patients, true negative in 96 patients, false positive in 16 patients and false negative in 35 patients. The overall sensitivity and specificity of PET for detection of LN metastasis were 50.0% and 85.7% respectively. The positive predictive value and accuracy of FDG-PET for detection of axillary lymph node metastasis were 68.6% and 71.9% respectively.

Conclusions: These data indicate that FDG-PET is a relatively specific technique in patients with gross metastatic lesions in the lymph nodes from breast cancer. However, inflammatory lesions (probably related to biopsy of the primary lesion) may adversely affect the specificity of the test. Sentinal lymph node imaging remains a powerful technique in identifying the lymph node which are at risk for microscopic metastasis and should be routinely performed for this purpose.