A 48-year-old woman with a T2N1M0 (Stage IIA) ER-positive, HER2-negative invasive ductal carcinoma undergoes neoadjuvant chemotherapy and achieves a pathological complete response (pCR). Which scoring system is used intraoperatively to assess sentinel lymph node status and determines eligibility for axillary lymph node dissection avoidance?
- A Nottingham Grading System
- B Sentinel node one-step nucleic acid amplification (OSNA) assay ✓
- C Van Nuys Prognostic Index
- D Oncotype DX recurrence score
Correct answer: B. Sentinel node one-step nucleic acid amplification (OSNA) assay
Explanation
The OSNA (One-Step Nucleic Acid Amplification) assay detects CK19 mRNA in sentinel lymph node homogenates intraoperatively within 30–40 minutes, allowing real-time decision-making on axillary dissection. Nottingham grades invasive carcinoma histologically; Van Nuys is used for DCIS; Oncotype DX is a postoperative genomic test guiding adjuvant chemotherapy decisions for ER+ HER2− early breast cancer.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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