217P - The routine use of sentinel lymph node biopsy in high risk DCIS lesions is not justified

• Published in: Annals of oncology Vol. 30; p. v73
• Main Authors: Preat, F., Bohlok, A., Donckier, V., Nogaret, J.M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2019
• ISSN: 0923-7534; 1569-8041
• DOI: 10.1093/annonc/mdz240.042

The use of sentinel lymph node biopsy (SLNB) during breast surgery for ductal carcinoma in situ (DCIS) is controversial. It is accepted in high risk lesions (high histological grade, palpable, large >25mm, and multifocal lesions) since it avoids a second operation if the definitive diagnosis reveals infiltrating ductal carcinoma (IDC) and its recommended due to some technical obligations in patients with planned total mastectomy or with tumor localization to the upper outer quadrant.. We aimed to evaluate the use of SLNB in patients with preoperative diagnosis of high risk DCIS lesions.
A monocentric retrospective study was conducted on 467 patients with primary diagnosed DCIS operated for partial or total mastectomy with or without SLNB. The frequency of each risk factor, and the incidence of IDC were calculated in the overall series. The predictive value of each risk factor is calculated by comparing these factors in the groups depending to the definitive pathology (IDC vs DCIS) using the chi square test. A value of p<0.05 was considered significant.
Breast surgery was done within a median of 42 ± 23 days of DCIS diagnosis. Median age was 57± 10 years. High risk DCIS lesions accounted for 73.1% of all cases (342/468). Grade III lesion, multifocal, palpable and larger than 25mm lesions were present in 263 (56.3%), 61 (13.1%), 86 (18.4%) and 99 (21.2%) respectively. IDC was diagnosed in 95/468 patients (20.3%) in the global series and in 75patients/342 (22%) in the patients with high risk lesions. A palpable lesions and a tumor diameter >25mm were associated with higher risk of invasive carcinoma (p=0.007 and p=0.017 respectively).Overall SLNB was done in 383 patients (82%), of which 318 patients (83%) had high risk lesions. A Positive SLN was detected in overall 5 patients (1.3%), all of which had high risk lesions (5/318: 1.6%).
In our study, the preoperative classification of high risk lesion showed a 79% sensitivity (75/95) and a 22% specificity (75/342) of detecting IDC. A positive SLN was found in only 1.6% of patients with high risk CDIS lesions operated for SLNB. The use of SLNB in patients with high risk DCIS avoids reoperation in 22% of cases. Nevertheless the low risk of positive SLN finding in this setting cannot justify its routine use.
Jean Marie Nogaret.
Has not received any funding.
All authors have declared no conflicts of interest.