Is sentinel lymph node biopsy alone accurate for breast cancer mastectomy? Results of a cohort study of 2423 patients.

Abstract Backgroud : Few patients with mastectomy and only with pN0(i+) or pN1mi sentinel node (SN) were included in randomized trial. To demonstrate SN biopsy accuracy for mastectomy. Methods: We examined results of SN among a multi-institutional cohort of patients, <=cT2-N0, who required total mastectomy, according to SN status and complementary axillary lymph-node dissection (cALND) or not. We have analyzed involved non-sentinel node (NSN) rate at cALND, overall (OS) and disease-free survival (DFS). Results: Among 2423 patients we reported 1307 pN0(i-)SN, 120 pN0(i+)SN, 273 pN1miSN and 723 pN1macro-metastases SN with cALND respectively in 24.5, 73.3, 82.4 and 93.1%. Median follow-up was 42.72 months. Among 320 patients with pN0(i-)SN we observed 35 NSN macro-metastases (10.9%) and among 723 patients with SN macro-metastases, cALND was omitted in 50 patients (6.9%): in multivariate analysis, OS and DFS were not significantly different according to cALND or not. Among 120 patients with pN0(i+)SN and 273 with pN1miSN, cALND were respectively omitted in 32 and 48 patients: age, pT-size and SN-status were predictive of NSN involvement. In multivariate analysis, post-mastectomy radiotherapy, regional nodal irradiation and adjuvant chemotherapy were significantly correlated to cALND and a significant lesser DFS rate was reported for patients without cALND (HR: 3.861, p=0.002). Conclusion: SN biopsy appeared as an accurate procedure for axillary staging of breast cancer mastectomy for pN0 SN status. For pN1-macro-metastases it is not possible to propose to avoid cALND. When SN was involved by ITC or micro-metastases, omission of cALND is still controversial and should have a negative prognosis impact in relation with a down staging and under treatment.