What is the recurrence rate for Invasive Ductal Carcinoma (IDC) that is Human Epidermal growth factor Receptor 2 (HER2) positive?

Recurrence Rates for HER2-Positive Invasive Ductal Carcinoma

HER2-positive invasive ductal carcinoma has a significantly higher recurrence risk of approximately 20-30% without appropriate HER2-targeted therapy, with recurrence rates varying based on tumor size, nodal status, and hormone receptor status. 1

Recurrence Risk by Disease Characteristics

Tumor Size and Nodal Status

• Small tumors (T1a-b, ≤1cm), node-negative:

  • 5-year recurrence-free survival: 77.1% (recurrence rate of 22.9%) without HER2-targeted therapy 2
  • 5-year distant recurrence-free survival: 86.4% (distant recurrence rate of 13.6%) without HER2-targeted therapy 2
  • Patients with these small HER2+ tumors have 5.09 times higher recurrence rates compared to hormone receptor-positive tumors 2

• Node-positive or tumors ≥2cm:

  • Higher recurrence risk, requiring more aggressive therapy 1
  • Two or more positive lymph nodes significantly increases recurrence risk 3

Hormone Receptor Status Impact

• HER2+/HR+ disease:

  • 10-year recurrence-free survival: 75% (recurrence rate of 25%) 1
  • 10-year breast cancer-specific survival: 85% 1

• HER2+/HR- disease:

  • 10-year recurrence-free survival: 61% (recurrence rate of 39%) 1
  • 10-year breast cancer-specific survival: 70% 1
  • Higher risk of recurrence compared to HER2+/HR+ disease 3

Impact of Modern HER2-Targeted Therapy

The introduction of HER2-targeted therapies has dramatically improved outcomes:

• With paclitaxel + trastuzumab (APT trial):

  • 3-year disease-free survival: 98.7% (recurrence rate of only 1.3%) 1
  • 10-year invasive disease-free survival: 91.3% (recurrence rate of 8.7%) 1
  • 10-year breast cancer-specific survival: 98.8% 1

• With trastuzumab-containing regimens:

  • Consistent benefit regardless of tumor size or nodal status 1
  • Significant reduction in recurrence risk compared to historical rates 1

Risk Factors for Recurrence

Several factors are associated with increased recurrence risk in HER2+ breast cancer:

• Age less than 35 years 4
• Higher BMI 3
• Larger primary tumor size 3
• Residual disease after neoadjuvant therapy (non-pCR) 3
• Low tumor-infiltrating lymphocytes (TILs) 3
• Low Ki67 expression 3

Clinical Implications

1. For small (T1b, 0.6-1.0 cm) node-negative tumors:

   • HER2-targeted therapy is recommended due to higher recurrence risk compared to HER2-negative tumors of similar size 1
   • Paclitaxel + trastuzumab is preferred for low-risk, stage I disease 1

2. For node-positive or tumors ≥2cm:

   • More intensive HER2-targeted regimens are recommended 1
   • Consider dual HER2 blockade with pertuzumab + trastuzumab 5

3. For residual disease after neoadjuvant therapy:

   • T-DM1 significantly improves outcomes (50% reduction in recurrence risk) 1

Important Caveats

• Recurrence risk is significantly higher without appropriate HER2-targeted therapy
• Risk assessment should incorporate multiple factors (tumor size, nodal status, HR status, age)
• Long-term follow-up is essential as some recurrences may occur after 5 years
• The risk-benefit ratio strongly favors HER2-targeted therapy even for small tumors due to the significant recurrence risk reduction

The introduction of effective HER2-targeted therapies has transformed the prognosis of HER2+ breast cancer from having one of the worst outcomes to having outcomes comparable to or better than some other breast cancer subtypes when appropriately treated.