Iodine Seed-Marking Protocol for Response-Guided Axillary Treatment After Systemic Therapy for Node-Positive Breast...

Area of Science:

• Oncology
• Surgical Oncology
• Breast Cancer Research

Background:

• Most node-positive breast cancer patients undergo axillary lymph node dissection (ALND) or radiation (RT) after primary systemic treatment (PST).
• The necessity of axillary treatment for patients achieving a pathologic complete response (pCR) post-PST is uncertain, leading to potential overtreatment.

Purpose of the Study:

• To evaluate the oncologic outcomes of a response-guided axillary treatment strategy.
• To assess the efficacy of the MARI (iodine seed-marked) lymph node protocol in patients with clinically node-positive (cN+) breast cancer who achieve pCR after PST.

Main Methods:

• A single-center cohort study included cN+ breast cancer patients with limited axillary lymph nodes treated with the MARI protocol (July 2014-December 2021).
• Patients underwent MARI-marked lymph node excision post-PST. Those with pCR (ypN0) avoided further axillary treatment; those with residual disease (ypN+) received RT.
• Oncologic outcomes, including axillary recurrence, 5-year invasive disease-free survival (iDFS), and overall survival (OS), were analyzed.

Main Results:

• Of 350 patients, 135 (39%) had ypN0 and received no further axillary treatment.
• The axillary recurrence rate was low: 0.7% for ypN0 and 2.3% for ypN+ patients.
• Five-year iDFS was 93% for ypN0 and 87% for ypN+; 5-year OS was 98% for ypN0 and 93% for ypN+.

Conclusions:

• Response-guided axillary treatment using the MARI protocol is associated with a very low axillary recurrence risk in selected cN+ breast cancer patients post-PST.
• This strategy effectively identifies patients who can avoid axillary overtreatment while maintaining excellent oncologic outcomes.
• The MARI protocol offers a viable approach for de-escalating axillary treatment based on treatment response.