Low incidence of lymph node metastasis in patients with microinvasive breast cancer: a Korean nationwide study

Clinicopathological features of microinvasive lobular carcinoma

AIMS

Microinvasive lobular carcinoma (MILC) is a rare form of minimally invasive carcinoma with incomplete pathological and clinical characterisation. We sought to identify the clinical and pathological features of MILC diagnosed at our institution between 2009 and 2023.

METHODS AND RESULTS

Patient demographic, pathological and clinical data were collected. Patients with a prior or synchronous history of invasive carcinoma were excluded. The study cohort included 30 female patients with a median age of 53 years. The most common imaging target was microcalcifications (63%). MILC was diagnosed on biopsy alone in three cases (10%), excision alone in 22 cases (73%) and on both biopsy and excision in five cases (17%). Most MILCs were unifocal (57%). MILCs were associated with classic lobular carcinoma in-situ (LCIS) in 90% of cases, florid LCIS in 27% and pleomorphic LCIS in 17%. None of 21 patients (70%) who underwent sentinel lymph node biopsy had lymph node involvement. Biomarker status was available in 16 (53%) MILC; 12 were oestrogen receptor+/progesterone receptor+/human epidermal growth factor receptor 2- (ER+/PR+/HER2-), two were ER+/PR-/HER2-, one was ER-/PR-/HER2+ and one was ER-/PR-/HER2 2+ but insufficient for fluorescence in-situ hybridisation (FISH) analysis. Median follow-up was 49 months. A patient with MILC at the excision margin of the index excision specimen did not undergo re-excision; 15 months later she developed an ipsilateral invasive carcinoma with ductal and lobular features and died of disease 73 months after initial diagnosis. All other 29 patients are alive with no evidence of disease.

CONCLUSION

MILC is a relatively indolent tumour arising in classic and variant LCIS, with a low risk of axillary or distant metastases.

Characteristics and risk factors of axillary lymph node metastasis of microinvasive breast cancer

PURPOSE

To select patients who would benefit most from sentinel lymph node biopsy (SLNB) by investigating the characteristics and risk factors of axillary lymph node metastasis (ALNM) in microinvasive breast cancer (MIBC).

METHODS

This retrospective study included 1688 patients with MIBC who underwent breast surgery with axillary staging at the Asan Medical Center from 1995 to 2020.

RESULTS

Most patients underwent SLNB alone (83.5%). Seventy (4.1%) patients were node-positive, and the majority had positive lymph nodes < 10 mm, with micro-metastases occurring frequently (n = 37; 55%). Node-positive patients underwent total mastectomy and axillary lymph node dissection (ALND) more than breast-conserving surgery (BCS) and SLNB compared with node-negative patients (p < 0.001). In the multivariate analysis, independent predictors of ALNM included young age [odds ratio (OR) 0.959; 95% confidence interval (CI) 0.927-0.993; p = 0.019], ALND (OR 11.486; 95% CI 5.767-22.877; p < 0.001), number of lymph nodes harvested (≥ 5) (OR 3.184; 95% CI 1.555-6.522; p < 0.001), lymphovascular invasion (OR 6.831; 95% CI 2.386-19.557; p < 0.001), presence of multiple microinvasion foci (OR 2.771; 95% CI 1.329-5.779; p = 0.007), prominent lymph nodes in preoperative imaging (OR 2.675; 95% CI 1.362-5.253; p = 0.004), and hormone receptor positivity (OR 2.491; 95% CI 1.230-5.046; p = 0.011).

CONCLUSION

Low ALNM rate (4.1%) suggests that routine SLNB for patients with MIBC is unnecessary but can be valuable for patients with specific risk factors. Ongoing trials for omitting SLNB in early breast cancer, and further subanalyses focusing on rare populations with MIBC are necessary.

Meta-analysis on axillary lymph node metastasis rate in ductal carcinoma in situ with microinvasion

OBJECTIVE

To address the question of axillary lymph node staging in ductal carcinoma in situ with microinvasion (DCIS-MI), we retrospectively evaluated axillary lymph nodes metastasis (ALNM) rate in a cohort of postsurgical DCIS-MI patients. By analyzing these data, we aimed to generate clinically relevant insights to inform treatment decision-making for this patient population.

METHODS

A systematic search was conducted on PubMed, Web of Science, Embase, The Cochrane Library, CNKI, Wanfang Database, Wipe, and China Biomedical Literature Database to identify relevant publications in any language. All the analyses were performed using Stata 16.0 software.

RESULTS

Among the 28 studies involving 8279 patients, the pooled analysis revealed an ALNM rate of 8% (95% CI, 7% to 10%) in patients with DCIS-MI. Furthermore, the rates of axillary lymph node macrometastasis, micrometastasis, and ITC in patients with DCIS-MI were 2% (95% CI, 2% to 3%), 3% (95% CI, 2% to 4%), and 2% (95% CI, 1% to 3%), respectively. Moreover, 13 studies investigated the non-sentinel lymph node (Non-SLN) metastasis rate, encompassing a total of 1236 DCIS-MI cases. The pooled analysis identified a Non-SLN metastasis rate of 33% (95% CI, 14% to 55%) in patients with DCIS-MI.

CONCLUSION

The SLNB for patients with DCIS-MI is justifiable and could provide a novel therapeutic basis for systemic treatment decisions.