What is the recommended treatment plan for a patient with infiltrating mammary carcinoma, grade 3, and high-grade ductal carcinoma in situ, with negative lymph nodes?

Treatment Plan for Infiltrating Mammary Carcinoma with High-Grade DCIS and Negative Lymph Nodes

For a patient with infiltrating mammary carcinoma (grade 3), high-grade DCIS, and negative lymph nodes who has undergone a mastectomy, adjuvant systemic therapy with chemotherapy followed by endocrine therapy (if hormone receptor-positive) is strongly recommended to reduce the risk of recurrence and improve survival.

Radiation Therapy Considerations

• Post-mastectomy radiation therapy should be strongly considered in this case due to high-grade disease and presence of suspicious lymphatic invasion, even with negative lymph nodes 1
• For patients with negative axillary nodes but high-risk features (such as grade 3 histology and lymphovascular invasion), radiation therapy to the chest wall with consideration of regional nodal irradiation may reduce locoregional recurrence 1
• The MA.20 trial showed that patients with high-risk node-negative disease (including those with grade 3 histology) had improved 10-year disease-free survival with regional nodal irradiation (83.7% vs 72.4%) 1

Systemic Therapy Recommendations

Chemotherapy

• Adjuvant chemotherapy is recommended for this patient with grade 3 disease, which is considered high-risk even with negative nodes 1
• For patients who have undergone mastectomy, chemotherapy should be administered before radiation therapy when both are indicated 1
• Standard chemotherapy regimens for breast cancer should be used, with paclitaxel 175 mg/m² intravenously over 3 hours every 3 weeks for 4 courses often administered sequentially to doxorubicin-containing combination chemotherapy 2

Endocrine Therapy (If Hormone Receptor-Positive)

• If the tumor is estrogen receptor (ER) and/or progesterone receptor (PR) positive, adjuvant endocrine therapy is recommended (category 1) 1
• For premenopausal women, tamoxifen 20 mg daily for 5 years is the standard recommendation 3
• For postmenopausal women, an aromatase inhibitor is preferred 1

HER2-Targeted Therapy (If HER2-Positive)

• If the tumor is HER2-positive, trastuzumab should be added to the treatment regimen for a total of one year (category 1) 1
• Trastuzumab may be administered concurrently with radiation therapy and with endocrine therapy if indicated 1

Risk Stratification and Treatment Algorithm

1. Determine receptor status (ER, PR, HER2) if not already known

   • This is critical for treatment planning 1

2. For hormone receptor-positive disease:

   • If tumor >1 cm: Adjuvant chemotherapy followed by endocrine therapy 1
   • If tumor 0.6-1.0 cm: Consider adjuvant chemotherapy plus endocrine therapy based on other risk factors 1

3. For hormone receptor-negative disease:

   • Adjuvant chemotherapy is strongly recommended regardless of tumor size due to high grade 1

4. For HER2-positive disease:

   • Add trastuzumab to chemotherapy regimen (category 1) 1

5. Post-mastectomy radiation therapy decision:

   • Strongly consider in this case due to grade 3 histology and suspicious lymphatic invasion 1
   • Include chest wall with consideration of regional nodal irradiation 1

Follow-Up Recommendations

• Interval history and physical exam every 4-6 months for 5 years, then every 12 months 1
• Annual mammography of the contralateral breast 1
• For patients on tamoxifen: annual gynecologic assessment every 12 months if uterus present 1
• For patients on aromatase inhibitors: monitoring of bone health with bone mineral density determination at baseline and periodically thereafter 1

Important Considerations and Caveats

• The presence of high-grade DCIS alongside invasive carcinoma increases the risk profile of this patient, warranting aggressive therapy 4, 5
• Despite negative lymph nodes, the high grade (grade 3) and suspicious lymphatic invasion are poor prognostic factors that warrant consideration of more aggressive therapy 6
• The risk of both local and distant recurrence is significantly higher in high-grade disease, even with negative nodes 6
• An active lifestyle and maintaining ideal body weight (BMI 20-25) may lead to optimal breast cancer outcomes 1