P3-07-43: The Impact of Timing in Sentinel Lymph Node Biopsy in Primary Breast Cancer.
Authors: U Güth, SM Schmid, ME Myrick, EC Obermann, CT Viehl, C Rochlitz, F Forrer
Journal: Cancer Research (2011)

Abstract Background: There is minimal data concerning the impact of timing on the radiolabeled colloid marked sentinel lymph node (SLN) procedure. Some surgeons believe that the operation should be performed as the first case in the morning because a delay could theoretically lead to a variation in number of lymph nodes removed; there could be a) an artificially higher number due to diffusion of the radiolabeled colloid, or b) a lower number due to decay of the radiolabeled colloid. We examine the correlation between the number of SLN removed and the time of day when the SLN procedure was performed. Methods: Between January 2003 and December 2009, 391 SLN procedures were performed in histologically confirmed invasive breast carcinomas at the University Women's Hospital Basel, Switzerland. In line with the procedure defined by the “Swiss Multicenter Sentinel Lymph Node Study in Breast Cancer Patients”, each patient underwent standard labeling, removal and pathological diagnosis of the SLN. In all cases, lymphatic mapping was performed with 99mTc-labeled nanocolloid the day before the operation between 2.00 and 3.00 p.m. In addition, 2–4 ml of patent blue V was injected 5–10 minutes prior to incision. The radiolabeled colloid marked SLN were intraoperatively identified by the use of a handheld gamma probe. All samples were sent for immediate assessment to the local Institute of Pathology. The number of lymph nodes was determined and frozen sections were performed. The timing of the SLN removal can be pinpointed unequivocally in all cases, since the pathology report records the arrival of the tissue samples for frozen section to the exact minute. In order to analyze the correlation between the timing of surgery on the operation day and the number of lymph nodes removed, we calculated the minutes from the beginning of the operating schedule in the morning (8.00 a.m.) until the arrival of the tissue samples in the frozen section laboratory (including subtraction of fifteen minutes handling and transport time). In order to calculate the association between the timing of the operation on the operation day and the number of the SLN removed, nonparametric spearman correlation (Spearman-Rho) was used; negative values of the coefficient rho indicate a descending trend. Results: In 391 procedures, 928 SLN (median: 2; range: 1–11) were removed. Although blue dye was used in all cases, in the majority of cases (50.8%, n=471) the SLN were marked exclusively by radiolabeled colloid and only detected by the use of the handheld gamma probe. Only in 27 of the 928 SLN (2.9%), did the surgeon identify the lymph nodes through the blue coloration alone. The median time between start of the operation timetable and the SLN removal was 150 minutes (range: 25–420). There was a weak negative association between timing and the number of SLN removed (Rho=-0.070; p=0.168), i.e. there was a small, non-significant decrease in the number of SLN removed at a later time in the day. Conclusion: After mapping SLN the previous day by using radiolabeled colloid method, the timing on the day of the operation has no relevant impact on the number of SLN removed. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-07-43.