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

Background and aims Sentinel lymph node (SLN) biopsy has been widely used i n 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 S LN to predict the regional lymph node status. Method We prospectively studied 80 women (mean age 56 years) with breast ca ncer. Thirty-four of them were T1 and the remaining 46 were T2. Patients we re divided into two groups. Group A, 36 patients were injected subdermally, surrounding the tumour site. Group B, 44 patients were injected peritumour ally guided by ultrasound if non-palpable. Planar images were performed 15 min after the injection and continued until SLN identification. Before surg ery, blue dye injection was administered similarly to the radiocolloid. Aft er incision, a hand-held gamma probe was used to reach the SLN. All nodes h arvested were analysed by classic pathology techniques. Results Overall, lymphoscintigraphy allowed the detection of SLN in 75/80 p atients (94%). All subdermal lymphoscintigraphies were positive (36/36) com pared with 89% of peritumoural (39/44). Blue dye detected SLN in 23/31 pati ents (74%) after subdermal injection and in 24/34 patients (71%) after peri tumoural injection. The sensitivity to localize the SLN with lymphoscintigr aphy+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 w ere 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%, r espectively, for the subdermal group and 90% and 93% for the peritumoural g roup. Conclusions (1) Our results indicate that both techniques have similar resu lts. However, we suggest that T2 tumours with a size greater than 2.5 cm sh ould be excluded from the SLN technique, in order to improve the accuracy a nd negative predictive value. (2) Lymphoscintigraphy is essential for visua lizing the SLN, and blue dye can be helpful when the gamma probe does not l ocalize the SLN. ((C) 2001 Lippincott Williams & Wilkins).