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Tumour Flare — SCE Medical Oncology MCQ

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ModerateBreast CancerTumour FlareSCE Medical Oncology

A 65-year-old woman with bone-only metastatic breast cancer starts letrozole + palbociclib. After 4 weeks, she develops worsening bone pain and rising CA15-3 despite starting treatment. Imaging shows no new lesions but increased sclerosis at known bone metastatic sites. What is the most likely explanation?

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Correct answer: E — Tumour flare — a paradoxical worsening of symptoms/markers early in endocrine therapy reflecting treatment response (healing bone sclerosis)

Tumour flare (bone flare) occurs in approximately 15-25% of patients starting endocrine therapy for bone-predominant metastatic breast cancer. It presents with transient worsening of bone pain and/or rising tumour markers in the first 2-8 weeks of treatment, often accompanied by increased bone sclerosis on imaging (representing healing response). It must be distinguished from progression. Management is supportive (analgesia). The flare typically resolves within 4-8 weeks and is paradoxically a positive prognostic sign.

Reference: ESMO 2024 Metastatic Breast Cancer Guidelines; Coleman et al Eur J Cancer 1988