Isolated Tumor Cells in Sentinel Lymph Nodes of Primary Invasive Breast Carcinoma: A Cohort Analysis

• Published in: Clinical breast cancer Vol. 19; no. 4; pp. 286 - 291
• Main Authors: Bethune, Gillian C., Karkada, Manolhas A., DeCoste, Ryan, Barnes, Penny J., Rayson, Daniel
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2019
• Subjects: Adjuvant therapy decision; Cost savings; Cytokeratin immunohistochemistry; Isolated tumor cells; Sentinel lymph node biopsy; Adjuvant therapy decision; Cytokeratin immunohistochemistry; Isolated tumor cells; Cost savings; Sentinel lymph node biopsy
• ISSN: 1526-8209; 1938-0666
• DOI: 10.1016/j.clbc.2019.03.002

The practice of performing routine cytokeratin immunohistochemistry (CK-IHC) on sentinel lymph nodes in early stage invasive breast cancer leads to frequent identification of isolated tumor cells (ITCs), the clinical significance of which remains unclear. After emergence of guidelines that suggested limited clinical utility of ITC detection, routine CK-IHC (rCK-IHC) staining was discontinued at our institution. We studied the rate and clinical utility of ITC detection before and after the discontinuation of rCK-IHC. We retrospectively reviewed 2 cohorts of 250 consecutive early stage invasive breast cancer (IBC) patients with sentinel lymph node biopsies (SLNBs) in 2010 to 2011 (rCK-IHC) and 2015 to 2016 (selective CK-IHC [sCK-IHC]). Variables abstracted included: tumor histology, tumor size, grade, lymphatic-vascular invasion, hormone receptor expression, HER2 status, and nodal status including ITCs. All cases from the 2015 to 2016 cohort for which sCK-IHC was performed underwent pathology review. A clinical review of treatment decision effect and cost analysis was undertaken. Data were analyzed using descriptive statistics and Fisher exact test. In the rCK-IHC cohort, all 250 cases underwent CK-IHC staining versus 57 cases in the sCK-IHC cohort. There were 23 ITC cases observed in the rCK-IHC cohort compared with 11 in the sCK-IHC cohort (P = .049). Excluding lobular carcinomas, 19 ITC cases were observed with rCK-IHC versus 7 with sCK-IHC (P = .02). ITC detection did not affect adjuvant treatment decision-making and resulted in savings of at least Can$8000. Selective rather than routine use of CK-IHC staining for SLNB evaluation in early-stage IBC results in decreased ITC detection without affecting treatment decisions and leads to cost savings. The finding of isolated tumor cells (ITCs) in lymph nodes from resected early stage breast cancer has been found to have limited prognostic relevance. We examined 2 different strategies for ITC detection among cohorts of 250 patients over 2 different time intervals (2010-2011 and 2015-2016). There were significantly fewer cases of ITC observed over the latter time period during which selective, as opposed to reflex cytokeratin staining, was used (P < .02). This observation resulted in cost savings to the pathology laboratory and did not affect adjuvant treatment decision-making.