Question
A 46-year-old female patient with advanced HER2-positive breast carcinoma is planned for therapy with Trastuzumab. Before starting treatment, which baseline investigation is most crucial?
a) Spirometry
b) Liver enzyme panel
c) Echocardiographic assessment
d) Chest radiograph
e) Oral glucose tolerance test
Answer
c) Echocardiographic assessment
Detailed Explanation
Trastuzumab is a targeted monoclonal antibody against the HER2 receptor, widely used in HER2-positive breast cancer.
The most important toxicity to remember is cardiotoxicity, specifically:
- Reduction in left ventricular ejection fraction (LVEF)
- Risk of heart failure
- Increased risk when combined with anthracyclines
👉 Therefore, baseline and periodic cardiac monitoring is essential, and the best test is:
- Echocardiography (ECHO) → measures LVEF accurately and non-invasively
Other options:
- Spirometry → not relevant (no pulmonary toxicity concern)
- LFTs → not a major toxicity of trastuzumab
- Chest X-ray → no functional cardiac assessment
- Glucose tolerance test → unrelated
Cheat Sheet (Exam Gold Points)
- Drug: Trastuzumab
- Target: HER2 receptor
- Key toxicity: Cardiotoxicity
- Mechanism: ↓ LVEF → heart failure
- Risk ↑ with: Anthracyclines
- Baseline test: Echo (LVEF measurement)
- Monitoring: Repeat echo every 3 months
Flashcards
Q1: What receptor does trastuzumab target?
A: HER2 receptor
Q2: Most important adverse effect of trastuzumab?
A: Cardiotoxicity (↓ LVEF, heart failure)
Q3: Best baseline investigation before trastuzumab?
A: Echocardiogram
Q4: Which drugs increase trastuzumab cardiotoxicity risk?
A: Anthracyclines
Q5: What parameter is monitored on echo?
A: Left ventricular ejection fraction (LVEF)
MCQs (High Difficulty)
MCQ 1
A patient on trastuzumab develops dyspnoea. Which mechanism best explains this?
a) Coronary vasospasm
b) Dilated cardiomyopathy due to HER2 blockade
c) Pulmonary fibrosis
d) Valvular degeneration
Answer: b
Explanation: HER2 signaling is important for cardiomyocyte survival → blockade causes LV dysfunction.
MCQ 2
Which investigation is most sensitive for detecting early trastuzumab cardiotoxicity?
a) ECG
b) Troponin
c) Echocardiography
d) Chest X-ray
Answer: c
Explanation: Echo detects decline in LVEF early before clinical symptoms.
MCQ 3 (False question)
Which of the following statements about trastuzumab is false?
a) It targets HER2 receptor
b) It commonly causes hepatotoxicity
c) It can reduce LVEF
d) Risk increases with anthracyclines
Answer: b
Explanation: Hepatotoxicity is not a major adverse effect.
MCQ 4
Which parameter is primarily used to decide continuation of trastuzumab therapy?
a) Serum creatinine
b) LVEF
c) ALT level
d) HbA1c
Answer: b
Explanation: Therapy is withheld if significant drop in LVEF.
MCQ 5
Which of the following drugs shares a similar cardiotoxic risk pattern with trastuzumab?
a) Cyclophosphamide
b) Doxorubicin
c) Methotrexate
d) Tamoxifen
Answer: b
Explanation: Anthracyclines like doxorubicin are synergistically cardiotoxic.
Summary for Quick Exam Revision
Trastuzumab is a HER2-targeted monoclonal antibody used in breast cancer, with cardiotoxicity being its most clinically significant adverse effect. This toxicity manifests as a reduction in left ventricular ejection fraction and may lead to heart failure, particularly when used alongside anthracyclines. Because HER2 signaling plays a role in cardiomyocyte survival, its inhibition leads to reversible myocardial dysfunction. Therefore, echocardiography is mandatory before starting therapy to establish baseline cardiac function and is repeated periodically during treatment. Other investigations like liver function tests, chest X-ray, and glucose tolerance testing are not routinely required for trastuzumab initiation. Monitoring LVEF is central to decision-making regarding continuation or cessation of therapy, making echocardiography the most important pre-treatment investigation.