skip to main content

Breast Cancer — SCE Medical Oncology MCQ

Instant feedback + full explanation. One question, done properly.

HardBreast CancerBreast CancerSCE Medical Oncology

Ribociclib-letrozole is planned for a postmenopausal woman. Two baseline ECGs show QTcF 462 and 466 milliseconds, potassium is 3.0 mmol/L and she takes bendroflumethiazide. What should occur before the first ribociclib dose?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: E — Correct reversible factors and initiate ribociclib only when QTcF is below 450 milliseconds

Explanation lettering: E = shown as A · D = shown as B · A = shown as C · B = shown as D · C = shown as E

C is correct. The Kisqali SmPC states that ribociclib should be initiated only when QTcF is below 450 milliseconds and electrolyte abnormalities should be corrected. Hypokalaemia and a thiazide are reversible contributors requiring review before treatment. Starting at 600 or 400 mg does not remove the baseline QT criterion. Tamoxifen has its own QT liability and is not the endocrine partner used to solve this problem. Magnesium alone does not correct hypokalaemia or negate repeated QTcF prolongation. An alternative CDK4/6 inhibitor may be considered after reviewing the full interaction and cardiac profile if QTcF remains elevated.

Reference: Kisqali UK Summary of Product Characteristics: https://www.medicines.org.uk/emc/product/8110/smpc