KRT19 and neoplasm: More than a decade ago, Tsujimoto et al. established OSNA cutoff levels for SLN biopsy results interpretation, defining macrometastases as > 5000 copies/μL of CK19 mRNA, micrometastases as 250 to 5000 copies/μL, and absence of metastases or presence of isolated tumor cells (ITC) as < 250 copies/μL [10].