American Board of Internal Medicine (ABIM) Certification Practice Exam

What does the addition of bevacizumab to chemotherapy regimens for colorectal cancer do?

1. Increases chemoresistance

2. Reduces treatment duration

3. Modestly improves outcomes

4. Increases side effects significantly

The correct answer is: Modestly improves outcomes

The addition of bevacizumab to chemotherapy regimens for colorectal cancer is known to modestly improve outcomes. Bevacizumab is a monoclonal antibody that inhibits angiogenesis by targeting vascular endothelial growth factor (VEGF). This mechanism reduces the blood supply to tumors, thereby limiting their growth and metastasis. Clinical trials have demonstrated that combination therapy, which includes bevacizumab along with standard chemotherapy regimens, leads to an increase in progression-free survival for patients with metastatic colorectal cancer. While the improvement in overall survival is present, it is typically modest compared to what can be observed with more aggressive treatment approaches. The other options do not accurately reflect the clinical evidence supporting bevacizumab's role. The addition of bevacizumab does not significantly increase chemoresistance, as its primary function is not to alter the sensitivity of cancer cells to chemotherapy. Additionally, it does not reduce the duration of treatment; instead, it is often administered alongside ongoing chemotherapy, which may extend treatment duration. While the addition of bevacizumab may lead to increased side effects, particularly related to hypertension and potential gastrointestinal perforations, the benefit it provides in terms of improved outcomes outweighs these risks, making modest improvement in clinical results the most relevant effect.