Clinical significance of tumor cell seeding associated with needle biopsy in patients with breast cancer.

BACKGROUND/OBJECTIVE: The occurrence of iatrogenic tumor cell seeding (seeding) in needle tract scars formed by core needle biopsy (CNB) or vacuum-assisted biopsy (VAB) is well known. Some risk factors for seeding have been reported, but the clinicopathological risk factors and its prognosis have not been fully investigated. We evaluated the clinical features and prognosis of seeding. METHODS: We included 4405 patients who had undergone surgery (lumpectomy or mastectomy) with a diagnosis of breast cancer by preoperative CNB or VAB at our hospital between January 2012 and February 2021. Data of patients with confirmed presence of seeding in resected specimens were collected from pathological records. We analyzed the risk factors of seeding using logistic regression analysis and compared the ipsilateral breast tumor recurrence (IBTR) rate between cases based on the presence or absence of seeding in the lumpectomy group. RESULTS: Of the 4405 patients, 133 (3.0%) had confirmed seeding. Univariate analysis revealed the association of clinicopathological features of seeding with lower nuclear grade (NG1 vs NG2-3; p = 0.043), lower Ki-67 (<30 vs. ≥30; p = 0.049), estrogen receptor (ER) positivity (positive vs negative; p<0.01), and human epidermal growth factor receptor 2 (HER2) negativity (negative vs positive; p = 0.016). Multivariate analysis showed ER positivity (odds ratio, 5.23; p<0.05) as an independent risk factor of seeding. The IBTR rate was not significantly different between the seeding and non-seeding groups. CONCLUSIONS: Seeding was more likely to occur in ER positive, HER2 negative carcinomas with less aggressive features, and may remain subclinical if adequate adjuvant treatments are administered.

A case of lymph node dissection for contralateral axillary lymph node metastasis of ipsilateral breast tumor recurrence after identifying the primary lymphatic drainage by lymphoscintigraphy.

We report a case of total mastectomy and contralateral axillary lymph node dissection (ALND) in a patient with ipsilateral breast tumor recurrence (IBTR) and contralateral axillary lymph node metastasis (ALNM), with lymphoscintigraphy, confirming that the primary lymphatic flow was directed to the contralateral ALNM. The patient in the present case study is a 63-year-old woman. At the age of 46 years, the patient underwent lumpectomy and sentinel lymph node biopsy (SLNB) for left breast cancer. After surgery, she underwent whole-breast irradiation and hormone therapy (tamoxifen) for 5 years. On follow-up, she did not have recurrence. When she underwent breast ultrasound examination at the 17-year checkup after the initial surgery, she was diagnosed with tumor recurrence in the left conserved breast and with contralateral ALNM, without distant metastasis to any other organ. When re-SLNB is performed in patients with IBTR, the primary lymphatic flow is directed toward a lymph node other than the ipsilateral axillary lymph node (ALN). Therefore, it is necessary to discuss whether or not the contralateral ALNM in our case should be treated as stage IV. Therefore, we performed ALND after confirming that the primary lymphatic flow was directed toward the contralateral ALN as observed on lymphoscintigraphy and considering the contralateral ALNM as a localized lesion. Lymphoscintigraphy and intraoperative fluorescence imaging aid in the identification of the primary lymphatic flow. Lymph node metastases beyond the altered primary lymphatic flow are treated as localized lesions, and aggressive surgery is expected to be effective. There is a need to formulate guidelines on the treatment of IBTR considering changes in primary lymphatic flow.