American Board of Internal Medicine (ABIM) Certification Practice Exam

How can ductal carcinoma in situ (DCIS) be treated if the disease is extensive?

1. Observation

2. Intravenous chemotherapy

3. Breast-conserving therapy or mastectomy

4. Masectomy only

The correct answer is: Breast-conserving therapy or mastectomy

When ductal carcinoma in situ (DCIS) is diagnosed as extensive, the preferred treatment approach typically includes breast-conserving therapy or mastectomy. This approach is based on several factors, including the extent of the disease, the potential for local recurrence, and the patient's preferences. Breast-conserving therapy, often involving lumpectomy followed by radiation therapy, is suitable for patients with smaller, less extensive DCIS. However, when the disease is extensive—indicating a larger area of involvement within the breast or a higher likelihood of multifocality or recurrence—mastectomy may be indicated to reduce the risk of leaving residual disease behind. This treatment strategy aims to balance effective management of the disease with the patient's quality of life and preferences regarding breast conservation. Observational management is not advisable in cases of extensive DCIS due to the increased risk of progression to invasive cancer. Intravenous chemotherapy is also not typically used in the management of DCIS, as it is not considered an appropriate treatment modality for this non-invasive stage of breast cancer. Therefore, the combination of breast-conserving therapy or mastectomy provides a comprehensive approach tailored to the extent of the disease.