American Board of Internal Medicine (ABIM) Certification Practice Exam

What benefit does adjuvant tamoxifen provide in patients with estrogen receptor-positive DCIS?

1. Improves overall survival

2. Decreases local recurrence and contralateral breast cancer risk

3. Reduces tumor size

4. Enhances quality of life

The correct answer is: Decreases local recurrence and contralateral breast cancer risk

Adjuvant tamoxifen is a selective estrogen receptor modulator that plays a significant role in managing estrogen receptor-positive ductal carcinoma in situ (DCIS). The primary benefit of administering tamoxifen in this scenario is that it decreases the risk of both local recurrence of breast cancer and the development of contralateral breast cancer. Patients with DCIS have a risk of progression to invasive breast cancer, and those who are estrogen receptor-positive can particularly benefit from tamoxifen's mechanism, which blocks estrogen receptors in breast tissue. By doing so, tamoxifen effectively reduces the likelihood of tumor recurrence in the same breast and the emergence of cancer in the opposite breast. While tamoxifen is associated with improved outcomes in terms of local control, its impact on overall survival in the DCIS population specifically is less clear and not as well established as the reduction of recurrence rates. In terms of tumor size, while tamoxifen can impact the biology of existing tumors, its primary role is not to directly reduce tumor size in DCIS. Instead, it is preventative in nature, aimed at managing the risk of future malignancy. Quality of life can be influenced by treatment regimens, but this is more subjective and not primarily the goal of using tamox