BACKGROUND: Recent randomized trials such as INSEMA and SOUND identified patients with breast cancer for whom axillary surgery omission appears to have no detrimental oncologic impact. However, some have questioned the safety of omitting axillary surgery in patients with invasive lobular carcinoma (ILC), the most common special histology type. METHODS: We analyzed a prospectively maintained institutional ILC database containing 1029 tumor records. We identified those meeting INSEMA and SOUND criteria for axillary surgery omission (clinically node negative with axillary ultrasound, cT1-2 for INSEMA-eligible, cT1 for SOUND-eligible, no neoadjuvant therapy). We used chi-square and Wilcoxon rank-sum tests to evaluate factors associated with pathologic nodal positivity. Local and distant recurrence free survival for those omitting axillary surgery were explored using the Kaplan-Meier method. RESULTS: Overall, 205 patients with ILC met preoperative criteria for the INSEMA or SOUND trials, of whom 189 (92%) underwent axillary surgery. Of 189 INSEMA-eligible patients, 19.8% were node positive and 30.2% upstaged in T category. Of 99 SOUND-eligible patients, 18.4% were node positive and 34.6% upstaged in T category. Younger age was significantly associated with nodal positivity (INSEMA p = 0.003, SOUND p = 0.002). For the subset of patients who omitted axillary surgery, distant recurrence free survival was significantly worse compared to those who underwent axillary surgery in both INSEMA-eligible (p = 0.001) and SOUND-eligible cohorts (p = 0.0495). CONCLUSIONS: High rates of occult nodal positivity in ILC patients suggest the need for ILC-specific selection criteria for axillary surgery omission. Further studies are needed to evaluate potential impact on oncologic outcomes in this patient population.
Abeles et al. (Mon,) studied this question.
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