What is the recommended treatment plan for a patient diagnosed with invasive ductal carcinoma?

Treatment of Invasive Ductal Carcinoma

For appropriately selected patients with early-stage invasive ductal carcinoma, breast-conserving surgery with sentinel lymph node biopsy followed by whole-breast radiation therapy achieves equivalent survival to mastectomy, with adjuvant systemic therapy determined by hormone receptor and HER2 status. 1, 2

Surgical Approach

Breast-conserving surgery (BCS) is the preferred treatment for most patients with early-stage IDC when negative margins can be achieved with acceptable cosmesis. 3, 1, 2

• Perform sentinel lymph node biopsy rather than full axillary dissection for clinically node-negative disease, as this is now standard of care 1
• Margins >10 mm are adequate; margins <1 mm are inadequate and require re-excision 1
• Mastectomy is reserved for: multicentric disease, inability to achieve negative margins with acceptable cosmesis, radiation therapy contraindications (such as collagen vascular disease or prior therapeutic chest irradiation), or patient preference 1, 2

The evidence demonstrates equivalent survival between breast conservation and mastectomy: Nine prospective randomized trials showed no survival difference in meta-analysis, with local recurrence rates of 3-19% after breast conservation versus 4-14% chest wall recurrence after mastectomy 3

Radiation Therapy

Whole-breast radiation therapy is mandatory after breast-conserving surgery and reduces local recurrence risk by approximately two-thirds. 1, 2

• Hypofractionated radiation therapy is the preferred approach for most women receiving whole-breast irradiation 1
• Boost irradiation provides an additional 50% risk reduction and is indicated for patients with unfavorable risk factors including positive margins, young age, or high-grade tumors 1
• Radiation therapy can be omitted only in the context of mastectomy 2

Pathological Assessment Requirements

The pathology report must document the following to guide treatment decisions 1:

• Tumor size and histologic grade (Nottingham grading system)
• Evaluation of all resection margins with distance measurements
• Total number of lymph nodes removed and number containing metastases
• Immunohistochemical evaluation of estrogen receptor (ER) and progesterone receptor (PR)
• HER2 receptor expression status
• Presence of lymphovascular invasion
• Assessment of any accompanying DCIS component separately

Risk Stratification for Systemic Therapy

Risk assessment must consider 1:

• Tumor size (T stage)
• Histopathological grade (Nottingham grade 1-3)
• Lymph node involvement (number of positive nodes)
• ER/PR status
• HER2 status
• Patient age
• Presence of lymphovascular invasion

Adjuvant Systemic Therapy

Endocrine Therapy

For hormone receptor-positive disease (ER and/or PR positive), tamoxifen 20 mg daily for 5 years is indicated. 1, 4

• The FDA-approved dose is 20-40 mg daily, though doses greater than 20 mg per day have not shown additional benefit 4
• Five years of tamoxifen therapy is superior to shorter durations, with 10-year overall survival of 80% versus 74% for 2 years of treatment 4
• Continuation beyond 5 years does not provide additional benefit and may be harmful 4
• Tamoxifen reduces contralateral breast cancer incidence by 47% with 5 years of treatment 4

Chemotherapy

• Neoadjuvant chemotherapy is indicated for locally advanced disease, inflammatory breast cancer, or to downstage tumors for breast conservation 2
• Adjuvant chemotherapy decisions depend on calculated recurrence risk based on the risk stratification factors above 1

HER2-Targeted Therapy

• HER2-targeted therapy should be considered based on tumor size and node status for HER2-positive disease 1

Multidisciplinary Treatment Planning

Treatment planning requires multidisciplinary discussion involving medical oncologist, breast surgeon, radiologist, radiation oncologist, and pathologist before initiating therapy. 1

Follow-Up Surveillance

The surveillance schedule is 2:

• Years 1-3: Every 3-6 months with history, physical examination, and annual mammography
• Years 4-5: Every 6-12 months with history, physical examination, and annual mammography
• After 5 years: Annually with history, physical examination, and annual mammography
• Avoid routine imaging (CT, PET, bone scans) or tumor markers (CA 15-3, CA 27-29, CEA) in asymptomatic patients 2

Critical Pitfalls to Avoid

• Do not recommend mastectomy solely to avoid local recurrence risk, as both procedures carry equal local failure rates of 3-19% 3
• Do not omit radiation therapy after breast-conserving surgery, as this increases local recurrence risk by approximately three-fold 1, 2
• Do not continue tamoxifen beyond 5 years, as the NSABP B-14 trial demonstrated worse outcomes with 10 years versus 5 years of treatment (92% disease-free survival versus 86%, p=0.003) 4
• Do not perform axillary lymph node dissection for clinically node-negative disease, as sentinel lymph node biopsy is now standard 1