Abstract P2-01-07: Reoperative sentinel lymph node biopsy for ipsilateral breast tumor recurrence: Impact of axillary surgery and radiation therapy on lymphatic drainage patterns
Authors: Sato Ayaka , Sakai Takehiko , Moroo Fumiko , Kimura Kiyomi , Tanabe Masahiko , Horii Rie , Akiyama Futoshi , Iwase Takuji 
Published: May 2015

Abstract
Background: While sentinel lymph node biopsy (SLNB) is a well-established method for patients with clinically node-negative primary breast cancer, reoperative sentinel lymph node biopsy (re-SLNB) for ipsilateral breast tumor recurrence (IBTR) still remains controversial. The aim of this study was to evaluate the location of reoperative sentinel lymph nodes (re-SLNs) and the factors related to aberrant drainage patterns after breast conserving surgery (BCS).
Methods: Between April 2005 and August 2013, we performed re-SLNB on 132 patients who developed IBTR with no metastatic lymph nodes in preoperative examination. Both injection of radioisotope (Tc-99m phytate) and preoperative lymphoscintigraphy were performed on 97 patients of them, who were eligible for this retrospective study. We divided these patients into two groups according to their previous axillary surgery: 55 patients with just SLNB or no axillary surgery to the group S, and 42 patients with previous axillary lymph node dissection (ALND) to the group D. The patients in the group S were divided into two subgroups: 19 with adjuvant radiation therapy (RT) and 36 without RT. We compared visualization rates of lymph drainage patterns in these groups statistically by using Chi-square test. We evaluated the relationship between previous local treatments and lymphatic drainage patterns.
Results: Number of cases in which lymphatic drainage was visualized were 52 (94.5%) in the group S and 33 (78.6%) in the group D (P &lt; 0.001). Re-SLNs were observed at ipsilateral axilla in 47 patients (90%) in the group S and 19 patients (58%) in the group D (P &lt; 0.001), at internal mammary (IM) in 9 (17%) and 16(49%) (P &lt; 0.01), and at contralateral axilla in 8 (15%) and 5(15%), respectively.
Within the group S, lymphatic drainage was visualized in 34 (94.4%) of 36 patients without RT and 18 (94.7%) of 19 patients who had received RT after BCS. Re-SLNs were visualized at ipsilateral axilla in 34 (100%) and 13 (72%) (P &lt; 0.01), at IM in 5 (15%) and 4 (22%), and at contralateral axilla in 1 (3%) and 7 (39%) (P &lt; 0.001).
Re-SLNB was successfully performed in 62 (94%) of 66 patients whose lymphatic drainage was observed at ipsilateral axilla. Metastases for carcinoma in re-SLNs were found in 8 (13%) of them. At IM, re-SLNB was successful in 15 (60%) of 25, and 2 (13%) of them were positive for cancer. At contralateral axilla, re-SLNB was successful in 8 (62%) of 13 while no metastases were found among them.
Conclusion: Previous ALND affected the visualization rates of re-SLNs. In patients after previous ALND, SLN was more likely to be in IM. Adjuvant RT effected a change in lymphatic drainage patterns, but did not affect the visualization rate of re-SLN. At ipsilateral axilla, the rates of successful re-SLNB and metastases at re-SLNs were similar to SLNB for primary breast cancer. Metastasis to SLN of recurrent cancer is one of the most important information for management of IBTR. However, it was very difficult to predict localization of re-SLN because lymphatic drainage patterns could have been affected by previous treatments. Therefore, we recommend re-SLNB using radioisotope with lymphoscintigraphy in surgery for IBTR.
Citation Format: Ayaka Sato, Takehiko Sakai, Fumiko Moroo, Kiyomi Kimura, Masahiko Tanabe, Rie Horii, Futoshi Akiyama, Takuji Iwase. Reoperative sentinel lymph node biopsy for ipsilateral breast tumor recurrence: Impact of axillary surgery and radiation therapy on lymphatic drainage patterns [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-01-07.