What is the recommended adjuvant management for a 63‑year‑old woman with papillary secretory microinvasive carcinoma that is strongly hormone‑receptor positive, HER2‑negative, with wide margins after breast‑conserving surgery and no sentinel lymph‑node biopsy?

Management of Papillary Secretory Microinvasive Carcinoma in a 63-Year-Old Woman

This patient requires adjuvant whole-breast radiotherapy followed by adjuvant endocrine therapy with an aromatase inhibitor for 5 years; sentinel lymph node biopsy should be strongly considered but may be omitted given the favorable tumor characteristics and the fact that systemic therapy decisions are already clear based on the strong hormone receptor positivity. 1

Radiotherapy Management

Adjuvant whole-breast irradiation is mandatory after breast-conserving surgery for invasive breast cancer, regardless of tumor size, grade, or nodal status. 1, 2, 3

• Radiotherapy reduces local recurrence by approximately two-thirds and improves overall survival—this benefit applies to all invasive breast cancer subtypes including hormone receptor-positive disease. 2, 4
• The preferred regimen is hypofractionated whole-breast irradiation: 40-42.5 Gy in 15-16 fractions over 3-4 weeks. 2, 4
• Radiotherapy cannot be omitted in this case because the patient does not meet the narrow criteria for omission: she would need to be ≥70 years old with a tumor ≤2 cm, grade 1 histology, and receiving tamoxifen—none of which fully apply here given the microinvasive/papillary histology and her age of 63. 2, 5, 6
• A boost to the tumor bed is not routinely required at age 63 (boosts are primarily indicated for patients <50 years). 3

Sentinel Lymph Node Biopsy Considerations

While SLNB was not performed, this represents a management decision point that warrants careful consideration. 1

• For clinically node-negative early breast cancer, sentinel lymph node biopsy is the standard of care and should be performed by experienced teams. 1
• However, SLNB may be considered optional in patients with particularly favorable tumors where the selection of adjuvant systemic therapy will not be affected by nodal status—which applies here given the strong HR-positivity mandating endocrine therapy regardless. 1
• If SLNB is performed and shows 1-2 positive nodes in a patient undergoing breast-conserving surgery with whole-breast radiation, no further axillary surgery is required. 1
• The false-negative rate of SLNB by experienced teams is 7-8%, meaning occult axillary disease probability after a negative sentinel node is <8%. 2

Practical approach: Given that this patient will receive endocrine therapy regardless of nodal status, and that she has already undergone wide-margin BCS without SLNB, proceeding directly to radiotherapy and endocrine therapy is reasonable. However, if there is any clinical concern for nodal involvement or if the patient/team desires complete staging, SLNB can still be performed before initiating radiotherapy. 1

Adjuvant Endocrine Therapy

An aromatase inhibitor is the preferred endocrine therapy for this postmenopausal woman with strongly hormone receptor-positive disease. 1, 7

• Letrozole, anastrozole, or exemestane should be administered for a minimum of 5 years. 1, 7
• Aromatase inhibitors are superior to tamoxifen in postmenopausal women with hormone receptor-positive breast cancer. 1, 2
• Endocrine therapy should begin after completion of radiotherapy or can be administered concurrently with radiation. 1
• Extended endocrine therapy beyond 5 years may be considered based on individual risk assessment and tolerance. 1, 7

Chemotherapy Decision

Chemotherapy is not indicated in this case. 2, 8

• The tumor is strongly hormone receptor-positive with no other high-risk features mentioned (no grade 3 histology, no extensive lymphovascular invasion, no HER2 positivity, patient age >35 years). 2
• Microinvasive carcinoma represents minimal invasive disease burden. 1
• The decision against chemotherapy is appropriate given the favorable biology and the patient's age. 2, 8

Treatment Sequence Algorithm

1. Complete pathology review: Confirm margins are widely clear, verify strong ER/PR positivity, confirm HER2-negative status. 1, 8
2. Consider SLNB (optional): Discuss with patient whether complete staging is desired; if performed and negative, no further axillary surgery needed. 1
3. Initiate whole-breast radiotherapy: 40-42.5 Gy in 15-16 fractions using hypofractionated schedule. 2, 4
4. Begin aromatase inhibitor: Start during or immediately after radiotherapy completion; continue for minimum 5 years. 1, 7
5. Surveillance: Annual mammography, regular clinical examinations; no routine imaging or tumor markers. 1

Common Pitfalls to Avoid

• Do not omit radiotherapy based on favorable tumor characteristics alone—the patient does not meet age and histologic criteria for safe omission. 2, 5, 6
• Do not use tamoxifen instead of an aromatase inhibitor in this postmenopausal woman—aromatase inhibitors provide superior outcomes. 1, 2
• Do not delay endocrine therapy indefinitely—it can be started concurrently with radiotherapy. 1
• Do not perform routine axillary dissection if SLNB is pursued and shows negative or 1-2 positive nodes in the setting of breast-conserving surgery with planned whole-breast radiation. 1
• Do not order routine staging scans, tumor markers, or bone scans in asymptomatic patients—these provide no survival benefit. 1