Day One: International Summit on Breast Cancer

For fifty years, a positive lymph node meant the whole axilla came out. Dr. Isabel Rubio's read of the AXANA registry closes that chapter for a large group of patients. When a clinically positive axilla becomes cancer-free after neoadjuvant treatment, a full axillary lymph node dissection adds nothing to three-year recurrence control, and it takes away the lymphedema.

Rubio walks through how neoadjuvant treatment has reshaped both breast and axillary surgery, and where the field goes next. On the breast, she makes the case that a breast pathologic complete response is not required for breast-conserving surgery, and that intraoperative ultrasound is delivering higher negative-margin rates and better cosmetic outcomes. On the axilla, she traces the path from routine dissection in the 1970s, to sentinel node biopsy in the 1990s, to today's targeted approaches, and lays out the prospective data that now support doing less. She closes on the real frontier: omitting sentinel node biopsy, and even surgery itself, in excellent responders, with genomic profiling beginning to stand in for surgical staging.

Key points for clinicians:

• A breast pathologic complete response is not a prerequisite for breast-conserving surgery. In the AXANA prospective registry, real-world 2020 data show roughly two-thirds of neoadjuvant patients undergoing breast conservation, with intraoperative ultrasound raising negative-margin rates and improving cosmesis.

• Targeted approaches now sit alongside sentinel node biopsy and axillary dissection. For the targeted axillary dissection and targeted lymph node biopsy, using clips, black ink, or magnetic or radioactive seeds, the false negative rate is below 5 percent in the majority of series.

• In AXANA, patients with a clinically positive axilla who achieve a complete pathologic response in the axilla show no significant difference in three-year axillary recurrence-free survival whether they undergo axillary dissection or a sentinel node biopsy or TAD procedure. - This confirms the retrospective data, and it removes the lymphedema burden of dissection.
  

In more than 5,000 AXANA patients presented at ASCO, tumor biology predicted axillary response, not nodal burden. Higher axillary pathologic complete response tracked with Ki-67 above 20 percent, triple negative and HER2-positive disease, and higher grade. The initial number of suspicious nodes was not associated with response, which should settle the three-versus-four-node debate.

• On radiation, NSABP B-51 (nearly 2,000 patients, five-year follow-up) found that regional nodal irradiation did not improve recurrence-free interval or disease-free survival in patients with a clinically positive axilla who reached a pathologic complete response. Rubio notes the caveats her radiation oncology colleagues raise: short follow-up and a possible triple negative signal.

• The next step is omission. MD Anderson's Kuerer work reported no ipsilateral breast recurrences at five years in highly selected HER2-positive and triple negative responders, and trials including EUBREAST, ASLAN, and OPTIMIST are testing omission of sentinel node biopsy. By 2030, a defined group of excellent responders may safely skip surgical staging altogether.

The most useful thing about a tumor board is watching experts disagree in good faith. In this session, an international panel takes two early-stage breast cancer cases and works them the way a real team would, out loud, with the tension left in.

Moderated by Professor William Gradishar, the panel walks a 35-year-old with BRCA1-associated triple-negative breast cancer and a 50-year-old with HER2-positive, hormone-receptor-positive breast cancer from diagnosis through surgery, systemic therapy, and the decisions in between. What comes through is how much thoughtful practice varies across the United States, Europe, and Asia, and how often the right answer is a shared decision rather than a protocol.

Key points for clinicians:

• Case 1 covers nodal clipping, neoadjuvant KEYNOTE-522 chemoimmunotherapy, PARP inhibition for BRCA carriers, and de-escalation of axillary surgery after an excellent response.

• Fertility preservation is treated as part of the plan, with egg or embryo harvesting and GnRH agonists during chemotherapy in a young patient.

• The panel openly disagrees on prophylactic bilateral mastectomy in a BRCA1 carrier, weighing contralateral risk against the limits of the survival evidence.

• Case 2 examines neoadjuvant therapy thresholds for HER2-positive disease, THP versus more intensive regimens, and where antibody-drug conjugates such as T-DXd are indicated before or after after surgery.

• Regional differences in mastectomy rates and de-escalation, across the US, South Korea, and China, show how the same case is managed differently around the world.