Axillary Staging Is Not Justified in Postmenopausal Clinically Node-Negative Women Based on Nodal Disease Burden.

Background: RxPONDER showed no benefit of adjuvant chemotherapy in postmenopausal women with estrogen receptor (ER) positive/human epidermal growth factor receptor 2 (HER2) negative breast cancer and limited nodal burden (pN1) with a recurrence score ≤ 25, suggesting that axillary staging could be omitted in cN0 patients if significant numbers of such women do not have pN2-3 disease. Here we evaluate the pN2-3 disease rate in a large cohort of postmenopausal women presenting with cN0 breast cancer.

Patients And Methods: Consecutive postmenopausal patients presenting with T1-2N0 breast cancer who underwent axillary surgery from February 2006 to December 2011 were identified. Clinicopathologic characteristics associated with pN2-3 disease were examined using chi-square or Fisher's exact tests.

Results: Of 3363 postmenopausal women with cT1-2N0 breast cancer (median age 58 years, IQR 48-67 years), median tumor size was 1.3 cm (IQR 0.90-1.90cm). Post-axillary staging, 2600 (77.3%) were pN0, 643 (19.1%) were pN1, and 120 (3.6%) were pN2-3. The pN2-3 disease rate did not differ across subtypes (4.4% HER2, 3.5% HR/HER2, 3.5% HR/HER2, p = 0.70). In the subset with HR/HER2 tumors, on multivariable analysis, age < 65 years (odds ratio [OR] 2.38, 95% confidence interval [CI] 1.32-4.49), lymphovascular invasion (OR 5.29, 95% CI 2.72-11.2), multifocal/centric tumors (OR 3.08, 95% CI 1.79-5.32), and tumor size > 2 cm (OR 5.51, 95% CI 3.05-10.4) were significantly associated with pN2-3 nodal burden. Of 506 patients with tumors > 2 cm, 49 (9.7%) had pN2-3 disease; in the subset of 90 patients age < 65 years who had multifocal/centric tumors > 2 cm, 23 (25.6%) had pN2-3 disease.

Conclusions: In postmenopausal women with cN0 disease, pN2-3 nodal burden is uncommon; omitting axillary staging would not miss a significant number of patients who might benefit from adjuvant chemotherapy. Information available preoperatively indicating a higher risk of nodal disease such as younger age and large, multifocal tumors should be considered in the multidisciplinary management of the axilla.