Must All Underarm Lymph Nodes Be Removed? New Approaches in Breast Cancer

The Importance of Underarm Lymph Nodes in Breast Cancer

Examining and removing underarm, or axillary, lymph nodes in breast cancer helps determine the extent of disease and remove cancer cells that may have spread. Axillary lymph node dissection is an important procedure for assessing whether cancer has spread to lymph nodes and plays a key role in staging. Lymph node status can be decisive in planning treatment and improving survival.

Why Are Axillary Lymph Nodes Removed?

If breast cancer cells have spread to lymph nodes, this indicates regional disease progression, and additional treatments such as chemotherapy, targeted drugs, or radiotherapy may be needed. Removing axillary lymph nodes is important for reducing the risk of recurrence and improving long-term survival. However, it can also cause complications such as loss of sensation in the underarm, arm swelling (lymphedema), and restricted movement.

Less Invasive Methods: Sentinel Lymph Node Biopsy

Less invasive approaches, such as sentinel lymph node biopsy, now aim to reduce these risks by examining only the first few lymph nodes, known as sentinel or guard nodes.

New Research – Extensive Axillary Dissection Is Not Necessary

Neoadjuvant treatment involves chemotherapy and/or targeted drugs given before surgery to shrink the tumor. In breast cancer, reducing tumor size facilitates surgery and allows more breast tissue to be preserved. It also allows assessment of tumor response and guides treatment after surgery.

JAMA Oncology published a study on April 25, 2024, showing low axillary recurrence rates with sentinel lymph node biopsy (SLNB) or targeted axillary dissection (TAD), instead of axillary lymph node dissection (ALND), after neoadjuvant chemotherapy in patients with clinically node-positive breast cancer at diagnosis. This indicates that ALND is unnecessary in these patients and supports omitting it in this group.

At 25 centers in 11 countries, researchers studied biopsy-proven stage II-III node-positive breast cancer treated with neoadjuvant chemotherapy in 1144 patients . Of these patients, 93% had N1 disease, 54% had ERBB2-positive disease (formerly known as HER2), and 66% had a breast pathologic complete response.

Targeted axillary dissection (TAD) combines sentinel lymph node biopsy with imaging-guided localization and removal of a lymph node marked and clipped during neoadjuvant chemotherapy. This technique aims to assess cancer spread in the axilla more precisely.

Methods

Overall, 666 patients (58%) underwent sentinel lymph node biopsy with dual-tracer mapping, and 478 (42%) underwent targeted axillary dissection. Targeted dissection included sentinel lymph node biopsy and imaging-guided localization of the clipped node.

The study's primary outcomes were the 3- and 5-year rates of any axillary recurrence. Secondary outcomes included locoregional recurrence, any invasive recurrence, both locoregional and distant, and the number of lymph nodes removed.

Results

• Nodal Radiation Treatment: Axillary radiation treatment was given to 85% of TAD patients and 78% of SLNB patients.
• Retrieval of the Clipped Node: The clipped node was successfully retrieved in 97% of TAD cases and 86% of SLNB cases.
• Number of Sentinel Lymph Nodes: The mean number of sentinel lymph nodes removed was 3 with TAD and 4 with SLNB (P < 0.001).
• Total Number of Lymph Nodes: The mean total number of lymph nodes removed was 3.95 with TAD and 4.44 with SLNB (P < 0.001).
• Axillary Recurrence Rates: The 3- and 5-year rates of any axillary recurrence were 0.65% and 1.0%, respectively. There was no significant difference in 3-year axillary recurrence between TAD (0.5%) and SLNB (0.8%).
• Locoregional and Invasive Recurrence Rates: The 5-year locoregional recurrence rate was 2.7%, and the rate of any invasive recurrence was 10%, with no significant difference between surgical groups.

In deciding whether to omit axillary dissection after neoadjuvant treatment, the study identified pathologic complete response (pCR) as an important factor. In particular, 66% of participants achieved a breast pCR. However, the overall results showed low axillary recurrence rates after omitting dissection regardless of whether a pathologic complete response was achieved .

According to these results, the presence of a pathologic complete response may support the decision to omit axillary dissection, but is not its sole determinant. Overall, omitting ALND in node-positive patients was associated with low axillary recurrence rates, suggesting that the approach is safe and effective.

The results may be related to the fact that many patients with clinically positive axillary nodes received axillary radiotherapy (RT). Axillary radiotherapy may help destroy tumor cells in the axillary region and contribute to low recurrence rates.

Conclusions and Recommendations

The study shows that early axillary recurrence is very rare after omitting axillary lymph node dissection (ALND) following neoadjuvant chemotherapy, and that recurrence rates are similar after targeted axillary dissection (TAD) and sentinel lymph node biopsy (SLNB).

These data encourage avoiding unnecessary surgery and using less invasive approaches while preserving quality of life. This offers a promising treatment strategy for both patients and oncology professionals.