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Soru

Zorluk: OrtaNeoplastic Processes

A 46-year-old woman comes to the oncology clinic to discuss treatment planning. She recently underwent a lumpectomy and sentinel lymph node biopsy for a right-sided breast mass. Surgical pathology confirmed invasive ductal carcinoma. Immunohistochemical staining demonstrates that the tumor is estrogen receptor-negative, progesterone receptor-negative, and strongly positive (3+3+) for a specific transmembrane receptor tyrosine kinase (HER2/neu). The patient is scheduled to begin an adjuvant chemotherapy regimen that includes a targeted monoclonal antibody against this receptor. The targeted receptor pathway is a primary driver of neoplastic proliferation in her tumor, but it is also physiologically essential for cellular survival and stress response in another major organ system. Based on the mechanism of action of the planned targeted therapy, which of the following baseline diagnostic studies is most critical to obtain prior to treatment initiation?

  1. Echocardiography to evaluate left ventricular ejection fractionCevap
  2. B
    Pulmonary function testing including carbon monoxide diffusion capacity
  3. C
    High-resolution computed tomography of the chest
  4. D
    Measurement of serum thiopurine methyltransferase activity
  5. E
    Baseline audiometry and thorough vestibular assessment

Cevap

Echocardiography to evaluate left ventricular ejection fraction is required to assess baseline cardiac function.
The patient's tumor is driven by HER2 overexpression, necessitating treatment with an anti-HER2 monoclonal antibody such as trastuzumab. Because HER2 signaling (often via HER2/HER4 heterodimerization) is physiologically critical for the maintenance and repair of cardiac myocytes under stress, inhibiting this pathway frequently leads to left ventricular contractile dysfunction. Therefore, a baseline evaluation of the left ventricular ejection fraction via echocardiography or radionuclide ventriculography is strictly required before initiating therapy to prevent the exacerbation of underlying heart failure.

Adım Adım Çözüm

1
Identify the molecular driver of the patient's neoplasm.
The tumor overexpresses HER2/neu, a receptor tyrosine kinase that promotes aggressive cell proliferation.
Tumor receptor status dictates the selection of targeted pharmacotherapy.
2
Determine the indicated pharmacologic intervention.
The patient will receive a HER2-targeted monoclonal antibody, such as trastuzumab.
Targeted therapies significantly improve survival in HER2-amplified malignancies.
3
Recall the physiologic role of the target receptor in healthy tissues.
In normal physiology, HER2 (pairing with HER4) is essential for the survival, repair, and stress-response of cardiac myocytes.
Understanding the foundational science of the receptor explains the mechanism of drug toxicity.
4
Select the appropriate clinical management step to prevent adverse events.
An echocardiogram or MUGA scan must be ordered to establish a baseline left ventricular ejection fraction (LVEF).
Because trastuzumab disrupts cardiac myocyte survival pathways, it can cause reversible dilated cardiomyopathy, necessitating strict cardiac monitoring.

Anahtar Kavram

Monoclonal antibodies targeting HER2/neu (e.g., trastuzumab) disrupt a signaling pathway that is not only oncogenic in breast tissue but also physiologically vital for cardiac myocyte survival, necessitating baseline and ongoing evaluation of left ventricular ejection fraction.
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Neoplastic Processes

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