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.