What is the recommended adjuvant endocrine therapy for a 40-year-old woman with estrogen receptor (ER) positive ductal carcinoma in situ (DCIS) with microinvasion, status post (s/p) bilateral mastectomy and sentinel lymph node biopsy (SLNB) with clear margins?

From the Guidelines

For a 40-year-old woman with ER-positive DCIS with microinvasion following bilateral mastectomy and SLNB with clear margins, the recommended adjuvant endocrine therapy is tamoxifen for 10 years, as this duration has been shown to reduce recurrence risk and offer additional benefit in reduction of the risk of contralateral breast cancer 1. Given the patient's premenopausal status and the hormone receptor positivity of her tumor, tamoxifen is an appropriate choice. The decision to extend treatment to 10 years should be individualized based on the patient's risk of late recurrence and tolerability of treatment side effects. Some key points to consider in this decision include:

• The patient's cancer stage and risk of late recurrence
• The tolerability and adverse effects of treatment experienced by the patient to date
• The potential benefits of extended therapy in reducing recurrence risk and preventing contralateral breast cancer
• The patient's preferences and values, as determined through a shared decision-making process As the patient has undergone bilateral mastectomy, the risk of recurrence in the remaining breast tissue is significantly reduced, but adjuvant endocrine therapy can still provide benefit in reducing the risk of new primary breast cancers and potentially improving overall survival. Regular follow-up is essential to monitor for side effects and address any concerns or issues that arise during treatment. The patient should be informed of the potential side effects of tamoxifen, including hot flashes, vaginal dryness, mood changes, and rare but serious risks such as endometrial cancer and thromboembolic events, and regular gynecologic examinations should be performed if the uterus is intact.

From the FDA Drug Label

The recommended dose is tamoxifen 20 mg daily for 5 years. Current data from clinical trials support 5 years of adjuvant tamoxifen therapy for patients with breast cancer Ductal Carcinoma in Situ (DCIS) The recommended dose is tamoxifen 20 mg daily for 5 years.

The recommended adjuvant endocrine therapy for a 40-year-old woman with ER positive ductal carcinoma in situ (DCIS) with microinvasion is tamoxifen 20 mg daily for 5 years 2.

• The patient's ER positive status and DCIS diagnosis support the use of tamoxifen.
• The recommended duration of therapy is 5 years, as supported by clinical trials 2.

From the Research

Adjuvant Endocrine Therapy for ER-Positive DCIS with Microinvasion

• The patient in question is a 40-year-old woman with estrogen receptor (ER) positive ductal carcinoma in situ (DCIS) with microinvasion, status post bilateral mastectomy and sentinel lymph node biopsy (SLNB) with clear margins.
• According to the study by 3, endocrine therapy is recommended for DCIS patients with positive hormone receptors.
• The study by 4 suggests that endocrine therapy should be targeted toward patients most likely to benefit from its use, and initiation was more common among women with ER-positive than ER-negative DCIS.
• The study by 5 recommends treatment with tamoxifen for patients with estrogen receptor positive tumors who have been treated with conservative surgery.

Factors Influencing Adjuvant Endocrine Therapy

• The patient's age, tumor characteristics, and treatment history are important factors in determining the recommendation for adjuvant endocrine therapy.
• The study by 6 describes multidisciplinary practices, including the use of endocrine therapy for ER-positive DCIS, and reports low local recurrence rates for patients with negative margins who received radiotherapy.
• The study by 7 investigated outcomes following treatment of ER-negative DCIS, but the patient in question has ER-positive DCIS, so this study is less directly relevant.

Recommendation for Adjuvant Endocrine Therapy

• Based on the available evidence, adjuvant endocrine therapy is recommended for the patient, given her ER-positive status and history of DCIS with microinvasion, as supported by studies such as 3 and 5.
• The choice of specific endocrine therapy, such as tamoxifen or an aromatase inhibitor, should be based on clinical characteristics and underlying disease, as well as the side effects of the drugs, as discussed in 3.