What is the pathological staging using the seventh and eighth edition of the AJCC? How would the stage change if her oncotype was 9?
Fifty-seven-year-old female presents with palpable mass in the upper outer quadrant of the left breast. Physical examination revealed a 4 cm mobile breast mass. There were no skin changes or palpable LNs. Bilateral diagnostic mammogram and ultrasound demonstrated a 3.5-cm hypoechoic density with irregular margins. The axillary LNs were negative. Ultrasound-guided core biopsy was consistent with invasive ductal carcinoma, nuclear grade 3. ER+/PR-/HER2/neu was not amplified. She underwent right partial mastectomy and axillary sentinel lymph biopsy and axillary LN dissection. Pathology demonstrated a 4.2-cm tumor consistent with invasive ductal carcinoma nuclear grade 3 with negative margins. Zero of three sentinel LNs contained tumor. Her oncotype was 18.