Omission of Surgical Axillary Lymph Node Staging in Patients with Tubular Breast Cancer.

Background: With more effective screening and treatment strategies, there is debate over whether surgical axillary staging should be deescalated for patients with small favorable breast cancers, such as tubular carcinoma (TC).

Patients And Methods: We identified patients with TC [defined as > 90% tubular tubules (angulated, not multilayered)] and known surgical axillary staging from our institutional database (2000-2018). Using the National Cancer Database (NCDB) (2004-2015), we identified patients with TC, ductal carcinoma in situ (DCIS), and pT1 estrogen receptor (ER)-positive invasive ductal carcinoma (IDC). We determined the rates of lymph node (LN) metastases, and the 5- and 10-year overall survival (OS) for patients with LN-negative versus LN-positive disease using the Kaplan-Meier method and propensity match analysis.

Results: In our institutional cohort, we identified 112 patients with T1 TC; only one (0.9%) patient had nodal involvement. In the NCDB cohort, we identified 6938 patients with T1 TC; 323 (4.7%) patients had axillary LN disease. The rate of axillary LN involvement for TC was comparable to that identified for patients with DCIS (4.2%), and much lower than that found for patients with grade I-III, T1, ER-positive IDC (20.5%), and patients with grade I, T1, ER-positive IDC (14.4%). There was no difference in 5-year (94.6% versus 95.4%, p = 0.67) and 10-year (83.9% versus 85.2%, p = 0.98) OS between TC patients with or without LN involvement. Kaplan-Meier survival curves even after propensity score matching suggest that tubular histology is independently associated with improved survival.

Conclusions: T1 TC is an excellent starting point for deescalation of surgical axillary staging.