Sentinel lymph node biopsy in breast cancer patients: subdermal versus peritumoural radiocolloid injection

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Abstract
Background and aims Sentinel lymph node (SLN) biopsy has been widely used in the management of melanoma and breast cancer. The aims of this study were (1) to compare the results obtained with the two main injection techniques, the peritumoural and subdermal; and (2) to determine the reliability of SLN to predict the regional lymph node status. Method We prospectively studied 80 women (mean age 56 years) with breast cancer. Thirty-four of them were T1 and the remaining 46 were T2. Patients were divided into two groups. Group A, 36 patients were injected subdermally, surrounding the tumour site. Group B, 44 patients were injected peritumourally guided by ultrasound if non-palpable. Planar images were performed 15 min after the injection and continued until SLN identification. Before surgery, blue dye injection was administered similarly to the radiocolloid. After incision, a hand-held gamma probe was used to reach the SLN. All nodes harvested were analysed by classic pathology techniques. Results Overall, lymphoscintigraphy allowed the detection of SLN in 75/80 patients (94%). All subdermal lymphoscintigraphies were positive (36/36) compared with 89% of peritumoural (39/44). Blue dye detected SLN in 23/31 patients (74%) after subdermal injection and in 24/34 patients (71%) after peritumoural injection. The sensitivity to localize the SLN with lymphoscintigraphy+blue dye+gamma probe was 92% (33/36) within the subdermal group and 91% (40/44) within the peritumoural group. Overall, five false negative SLN were found. All of these corresponded to T2 tumours with a size greater than 2.5 cm. The negative predictive value and the accuracy were 93% and 94%, respectively, for the subdermal group and 90% and 93% for the peritumoural group. Conclusions (1) Our results indicate that both techniques have similar results. However, we suggest that T2 tumours with a size greater than 2.5 cm should be excluded from the SLN technique, in order to improve the accuracy and negative predictive value. (2) Lymphoscintigraphy is essential for visualizing the SLN, and blue dye can be helpful when the gamma probe does not localize the SLN.