Retrospective audit of the yield of internal mammary lymph node dissection and literature review in the management of breast cancer.

BACKGROUND

Treatment of lymph node basins is prognostic and therapeutic for axillary lymph nodes (ALN) as well as internal mammary lymph nodes (IMLNs) in breast cancer. IMLNs can be the first echelon node for the inner/central quadrants of the breast. We evaluated the yield of IMLN dissection (IMLND) mainly in patients with inner and central tumors.

METHODS

IMLND was performed in 199 patients between 2000 and 2018, 127 of whom had tumors in the inner/ central quadrants. Clinico-pathological data were retrieved from Electronic Medical Records (EMR).

RESULTS

The median age was 50 (range: 24-81). Primary surgery was performed in 82 (41.2%), while 117 (58.8%) were operated post-chemotherapy. Overall, 124/199 (62.3%) had nodes identified in the specimen, more often in primary (61/82, 74.4%) than post-chemotherapy settings (63/117, 53.8%) (P = 0.003). A median of 1 (average: 1.24, range: 0-7) lymph nodes was dissected, and 1 (average: 1.5, range: 1-4) was involved. IMLN was positive in 46/199 (23.1%) patients, not significantly different in primary (21/82, 25.6%) versus post-chemotherapy (25/117, 21.4%) settings (P = 0.545). IMLN was involved in 44.8% of patients with ≥4 involved ALN and 8.2% with uninvolved ALN (P < 0.001). In the absence of ALN involvement and <2cm pT size, 9% of patients had positive IMLN in inner/central quadrant tumors. In univariate analysis, ALN positivity (P < 0.001), pT size (P = 0.023), and grade (P = 0.041) in primary and ALN involvement (P = 0.011) in post-chemotherapy patients were associated with IMLN involvement. On logistic regression, tumor size (OR: 13.914, P = 0.017) and ALN involvement (OR: 11.400, P = 0.005) in primary surgery and ALN involvement (OR: 7.294, P = 0.003) in post-chemotherapy patients correlated with IMLN involvement.

CONCLUSIONS

In inner/central quadrant tumors, IMLN is more likely involved with high ALN burden and tumor size >2 cm, whereas those with ≤2cm inner/central quadrant tumors and negative ALN have <10% probability of IMLN involvement.

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