American Board of Internal Medicine (ABIM) Certification Practice Exam

What is beneficial in treating metastatic gastric cancer if HER2 is overexpressed?

1. Combination chemotherapy

2. Trastuzumab

3. Immunotherapy

4. Radiation therapy

The correct answer is: Trastuzumab

The treatment of metastatic gastric cancer that overexpresses HER2 is significantly enhanced with the use of trastuzumab. This humanized monoclonal antibody specifically targets the HER2 protein, which is overexpressed in a subset of gastric cancers. By binding to HER2, trastuzumab inhibits the signaling pathways that promote cancer cell proliferation and survival, leading to decreased tumor growth. In cases where HER2 overexpression is present, the addition of trastuzumab to chemotherapy not only improves response rates but also prolongs overall survival compared to chemotherapy alone. This targeted approach is especially advantageous because it tailors treatment to the specific molecular characteristics of the tumor, maximizing effectiveness while minimizing unnecessary toxicity. The other treatment modalities mentioned do have their roles in the management of gastric cancer but are not specifically beneficial in the context of HER2 overexpression. Combination chemotherapy can be used in the general treatment of gastric cancer but lacks the targeted mechanism of trastuzumab. Immunotherapy may benefit gastric cancer in other circumstances but is not effective against HER2 specifically without the targeting aspect of trastuzumab. Radiation therapy is typically not utilized as a frontline treatment for metastatic gastric cancer involving HER2 overexpression, as its use is more limited in palliative settings or localized disease.