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Ki-67 Response NET — SCE Medical Oncology MCQ

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ModerateBreast CancerKi-67 Response NETSCE Medical Oncology

A 65-year-old woman with ER+/HER2- breast cancer has neoadjuvant endocrine therapy with letrozole for 6 months. Repeat core biopsy shows Ki-67 has dropped from 25% to 5%. What does this Ki-67 response indicate?

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Correct answer: B — Ki-67 response to neoadjuvant endocrine therapy is a strong prognostic biomarker

The POETIC trial established that Ki-67 measured after 2-4 weeks of AI therapy (perioperative window study) is a powerful prognostic marker. Post-AI Ki-67 ≤10% identifies patients with excellent prognosis on endocrine therapy alone. Persistently elevated Ki-67 (>10%) identifies patients at higher recurrence risk who may benefit from adjuvant chemotherapy. This dynamic Ki-67 assessment adds information beyond baseline Ki-67 and genomic assays by testing the tumour's real-time endocrine sensitivity.

Reference: https://www.nice.org.uk/guidance/conditions-and-diseases/cancer