Feasibility Study of Safe Breast Conservation in Large and Locally Advanced Cancers with Use of Radiopaque Markers to Mark Pre-Neoadjuvant Chemotherapy Tumor Margins

The lack of objective documentation of pre-neoadjuvant chemotherapy (NACT) margins after chemotherapy is a major constraint in performing safe breast-conserving surgery (BCS) in patients with locally advanced breast cancer (LABC). Using a novel method of marking pre-NACT tumor margins with indigenous silver wire markers, this prospective pilot study attempted to assess the feasibility of safe BCS in LABC patients by performing excision wide of the marked pre-NACT margins. LABC patients had sterile silver wire markers placed at all tumor margins percutaneously. Patients were then treated with NACT followed by wide local excision (WLE) incorporating pre-NACT margins (ex vivo on mastectomy specimen or in vivo in patients opting for BCS). The histology of the margins wide of the post-WLE cavity (pre-NACT) and post-NACT tumor was used to assess adequate disease clearance and safety of BCS. Altogether, 40 stage III breast cancer patients (mean tumor size 7.9 cm) were studied; none had marker-related complications. Following NACT, the tumor size assessed by markers showed average regression by 1.5 cm. The pre-NACT margins were histologically negative in 95% of the surgical specimens. In 2 (5%) patients both pre-NACT and post-NACT margins were positive; post-NACT margins were infiltrated in 14 (35%). The post-NACT WLE that is wide of the marked pre-NACT margins can achieve uninfiltrated margins in 95% of cases. If post-NACT margins are used to guide the WLE, 35% patients would have infiltrated margins, some of which would remain undetected, putting patients at high risk of local recurrence. This novel indigenous method of identifying tumor margins with sterile silver wire markers is safe, inexpensive, practical, and effective; and it may help perform safe BCS in a large proportion of LABC patients.