From the Guidelines
Chemotherapy is recommended for T1a HER2-positive breast cancers, with a preferred regimen of paclitaxel weekly for 12 weeks plus trastuzumab for a total of one year, due to the aggressive biological behavior of HER2-positive tumors and the significant reduction in recurrence risk with chemotherapy and HER2-targeted therapy. The most recent and highest quality study, published in 2023 1, suggests that for stage I, T1a HER2-positive breast cancers, chemotherapy may be considered on a case-by-case basis, with trastuzumab and endocrine therapy if hormone receptor-positive. This approach is consistent with the aggressive biological behavior of HER2-positive tumors, which carry a higher recurrence risk regardless of size. Even small HER2-positive tumors have approximately 5-10% risk of distant recurrence without systemic therapy, and the addition of chemotherapy with HER2-targeted therapy reduces this risk by about 50% 1.
Key considerations in treatment decisions include:
- Patient's overall health status
- Comorbidities
- Preferences
- Multidisciplinary tumor board discussion for borderline cases
- Tumor size and baseline nodal status
- Hormone receptor status
The use of genomic assays to guide treatment decisions is also important, particularly in determining the need for adjuvant chemotherapy in patients with ER-positive, HER2-negative cancers 1. However, for HER2-positive tumors, the focus remains on the combination of HER2-targeted therapy and chemotherapy to maximize recurrence risk reduction.
In terms of specific regimens, paclitaxel weekly for 12 weeks plus trastuzumab for a total of one year is a preferred option for lower-risk patients due to lower toxicity 1. For higher-risk patients or those with more advanced disease, other regimens such as docetaxel and carboplatin with trastuzumab (TCH) may be considered. Ultimately, treatment recommendations should be individualized and based on the latest evidence and guidelines.
From the FDA Drug Label
Patients with node-negative disease were required to have ≥ T1c primary tumor. The FDA drug label does not answer the question about chemotherapy benefit in T1a breast tumors that are HER2 positive.
From the Research
Chemotherapy Benefit in T1a Breast Tumors that are HER2 Positive
- The benefit of chemotherapy in T1a breast tumors that are HER2 positive is a topic of ongoing research, with studies suggesting that adjuvant chemotherapy plus trastuzumab may improve outcomes for patients with these tumors 2.
- A study published in 2023 found that adjuvant paclitaxel and trastuzumab is a reasonable treatment standard for patients with small, node-negative, HER2-positive breast cancer, with a 10-year invasive disease-free survival rate of 91.3% 3.
- Another study published in 2016 found that weekly paclitaxel with trastuzumab and pertuzumab is associated with a favorable overall survival and progression-free survival in patients with HER2-positive metastatic breast cancer 4.
- A 2013 study found that the combination of trastuzumab and paclitaxel plus capecitabine is an effective and well-tolerated regimen in the first-line therapy for women with HER2-positive metastatic breast cancer 5.
- A 2021 study found that neoadjuvant weekly paclitaxel and carboplatin with trastuzumab and pertuzumab achieves high pathologic complete response rates in HER2-positive breast cancer, with fewer grade ≥3 toxicities compared to other regimens 6.
Key Findings
- Adjuvant chemotherapy plus trastuzumab may improve outcomes for patients with T1a breast tumors that are HER2 positive.
- Paclitaxel and trastuzumab is a reasonable treatment standard for patients with small, node-negative, HER2-positive breast cancer.
- Weekly paclitaxel with trastuzumab and pertuzumab is associated with a favorable overall survival and progression-free survival in patients with HER2-positive metastatic breast cancer.
- The combination of trastuzumab and paclitaxel plus capecitabine is an effective and well-tolerated regimen in the first-line therapy for women with HER2-positive metastatic breast cancer.
- Neoadjuvant weekly paclitaxel and carboplatin with trastuzumab and pertuzumab achieves high pathologic complete response rates in HER2-positive breast cancer.