Abstract P1-07-30: Predictive factors of sentinel lymph node biopsy invasion in extended ductal carcinoma in situ treated by radical mastectomy
Authors: Hotton J , Salleron J , Rauch P , Buhler J , Leufflen L , Ameloot S , Marchal F 
Published: February 2018

Introduction: The incidence of ductal carcinoma in situ (DCIS) increased with the practice of organized breast cancer screening to reach 14 % in France in 2010. The incidence of positive sentinel lymph node biopsy (SLNB) ranged from 0 to 16.7 %. The main hypothesis would be the presence of an invasive contingent on the definitive analyze not identified preoperatively. The objective was to identify predictive factors of SLNB positivity in the management of extended DCIS treated by radical mastectomy.

Method: This study was retrospective, longitudinal, descriptive conducted at the Cancer Institute of Lorraine from January 2000 to July 2015. All patients whose management consisted of a radical mastectomy for an extended DCIS, associated with a sentinel lymph node procedure were included.

Results: 161 patients were included. The mean age at diagnosis was 56 years; 15 had a clinical nodule. The diagnosis was made in 63.3 % with macrobiopsies. Preoperatively, 16 patients (9.9 %) had DCIS associated with microinvasion (DCIS-MI) and the others were pure DCIS. An average of 3.9 ± 2.7 SLNB were sampled. Twelve patients (7.4 %) had a SLNB invasion. Eleven of them had axillary lymph node dissection (ALND) of which only 1 was positive. The final histological analysis found 104 pure DCIS (64.6 %), 23 DCIS-MI (14.3 %) and 34 occult invasive ductal carcinomas (IDC) (21.1 %). Mean follow-up was 41.1 months. There were 2 recurrences and 2 deaths.

N°Final histologyPreoperative histologyDCIS size (mm)PalpabilitySLNB typeSLNB positivityALND positivity1DCISDCIS60NoMacrometastase542DCISDCIS50NoMicrometastase203DCISDCIS10NoIsolated Tumor Cells1-4DCIS-MIDCIS90YesIsolated Tumor Cells105DCIS-MIDCIS-MI75YesIsolated Tumor Cells106IDCDCIS110YesMicrometastase107IDCDCIS70NoIsolated Tumor Cells108IDCDCIS80YesMicrometastase109IDCDCIS-MI100NoMicrometastase1010IDCDCIS-MI50NoMicrometastase1011IDCDCIS-MI60NoMicrometastase1012IDCDCIS-MI40YesMacrometastase10

Predictive factors were size of palpated mass (mean: 46 mm, p = 0.04) and microinvasion on biopsy (p = 0.02). Positivity of the SLNB was an overstaging risk factor on the final histology (p &lt; 0.001). Postoperative histological results were significantly different from preoperative (p = 0.001) with poor concordance (kappa = 0.15).

Discussion: After SLNB, the rate of secondary lymphedema in the literature was 5%. Our study included 7.4 % (12 cases) of axillary lesions, majority of which were unique micrometastases or isolated tumor cells (ITC). All predictive factors were identified in literature. In our study, mean size of palpated mass was 46 mm whereas it was 30 mm in literature. Of the 9.9 % of DCIS-MI, 4 patients had a positive SLNB. In cases of pure DCIS, the percentage of positive SLNB was reduced to 5.5 %. The rate of occult invasive ductal carcinoma was 21,1%, similarly like in literature where rate was in mean 23%.

Conclusion: The low rate of SLNB invasion in pure DCIS suggests that ALND is carried out in the presence of predictive factors. New techniques for identification of SLNB could report axillary staging after obtaining the definitive histologic results.

Citation Format: Hotton J, Salleron J, Rauch P, Buhler J, Leufflen L, Ameloot S, Marchal F. Predictive factors of sentinel lymph node biopsy invasion in extended ductal carcinoma in situ treated by radical mastectomy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-07-30.