American Board of Internal Medicine (ABIM) Certification Practice Exam

What is a common chemotherapy regimen used for stage IV colorectal cancer?

1. FOLFOX and Gleevec

2. 5-FU and leucovorin

3. FOLFIRI and temozolomide

4. Doxorubicin and cyclophosphamide

The correct answer is: 5-FU and leucovorin

The commonly used chemotherapy regimen for stage IV colorectal cancer includes 5-fluorouracil (5-FU) and leucovorin. This combination has been a standard treatment approach for metastatic colorectal cancer for several years. 5-FU is an antimetabolite that interferes with the synthesis of DNA and RNA, thereby inhibiting the growth of cancer cells. When used in combination with leucovorin, which enhances the efficacy of 5-FU, this regimen can lead to improved survival rates and is often combined with other treatments, such as oxaliplatin (FOLFOX) or irinotecan (FOLFIRI), in more comprehensive protocols. Other regimens mentioned do not typically represent standard treatment choices for stage IV colorectal cancer. For instance, Gleevec (imatinib) is primarily used for chronic myeloid leukemia and gastrointestinal stromal tumors, not colorectal cancer. Temozolomide is generally used for certain brain tumors, not colorectal malignancies. Doxorubicin and cyclophosphamide are often employed in breast cancer treatment rather than colorectal cancer. Thus, the choice of 5-FU and leucovorin aligns with established treatment guidelines for managing advanced colorectal cancer.