Predictive factors of axillary positive sentinel lymph node biopsy in extended ductal carcinoma in situ treated by simple mastectomy at once.

BACKGROUND: The incidence of positive sentinel lymph node biopsy (SLNB) in ductal carcinoma in situ (DCIS) ranged from 0 to 14%. The main hypothesis would be the presence of an invasive contingent on the final histology. The objective was to identify predictive factors of sentinel lymph node positivity in the management of extended ductal carcinoma in situ treated by simple mastectomy.

METHODS: This was a retrospective study carried out at the Lorraine Cancer Institute from January 2003 to December 2017. Women with DCIS on core-needle biopsy whose management consisted of simple mastectomy and SLNB procedure were included.

RESULTS: 188 patients were analyzed. Preoperatively, 18 patients (9.6%) had DCIS with microinvasion, while the others had pure DCIS. Eight patients (4.2%) had positive sentinel lymph node biopsy, the majority of which were single micrometastases. Predictive factor of node invasion was microinvasion on biopsy (p<0.01). Only in cases of pure DCIS, the percentage of positive SLNB was reduced to 2.9%. Invasive carcinoma was found in the majority of patients with positive axillary SLNB procedure (75%, n=6), compared to 16.7% (n=30) without SLNB involvement (p<0.01).

CONCLUSIONS: The low rate of positive sentinel node biopsy in pure ductal carcinoma in situ suggests that in the absence of microinvasion, the sentinel procedure would seem less appropriate. New techniques for identifying sentinel lymph node biopsy could report axillary staging after definitive histologic results.