Carbon (charcoal) tattoo localization of biopsy-proven metastatic axillary lymph nodes for targeted axillary dissection after neoadjuvant therapy in breast cancer: a systematic review and single -arm meta-analysis.

BACKGROUND

Targeted axillary dissection (TAD) using carbon tattooing aims to localize and excise biopsy-proven metastatic axillary nodes after neoadjuvant systemic therapy (NAST), potentially improving post-NAST axillary staging while enabling the de-escalation of axillary surgery.

METHODS

We systematically searched Scopus, Embase, PubMed, Web of Science, Cochrane CENTRAL, and ClinicalTrials.gov, supplemented by screening reference lists. Prospective and retrospective clinical studies evaluating carbon tattooing-guided targeted tattooed lymph node (TLN) excision in initially node-positive breast cancer patients treated with NAST were included. Random-effects generalized linear mixed models (GLMM) were used to pool the proportions of dichotomous outcomes. Continuous outcomes were pooled using a random-effects inverse variance model. The risk of bias was assessed using the ROBINS-I tool. Leave-one-out sensitivity analyses and a pre-specified clinical subgroup analysis (completion-ALND verification cohort vs. feasibility/no-mandatory-ALND cohort) were also performed.

RESULTS

Nine studies were included in this review. The pooled TLN identification rate was 0.94 (95% CI: 0.88-0.97). The pooled sentinel lymph node (SLN) identification rate was 0.754 (95% CI 0.541-0.888), with substantial heterogeneity between studies. TLN-SLN concordance was 0.554 (95% CI 0.333-0.755), indicating a moderate overlap between the tattooed node and SLN. In the completion-ALND verification cohorts, the pooled false-negative rate (FNR) of the targeted procedure versus ALND for residual nodal disease was 0.068 (95% CI 0.042-0.108). The pooled mean number of retrieved nodes was 3.25 (95% CI 2.54-3.96), and the pooled tattoo-to-surgery interval was 153.0 days (95% CI 131.9-174.2). Sensitivity analyses showed that no single study unduly influenced pooled estimates.

CONCLUSION

Carbon tattooing-guided targeted axillary procedures after NAST demonstrated high TLN retrieval and low verification-cohort FNR, supporting procedural feasibility for post-NAST axillary staging in initially node-positive breast cancer patients. However, variable SLN identification, moderate TLN-SLN concordance, and heterogeneity in technique and reporting support implementation within standardized multidisciplinary workflows with local audits. Further prospective comparative studies are required.