Response: Expression of Glucagon-Like Peptide-1 Receptor in Papillary Thyroid Carcinoma and Its Clinicopathologic Significance (Endocrinol Metab 2014;29:536-44, Min Jung Jung et al.)

Thank you for your interest and comments on our article entitled “Expression of glucagon-like peptide-1 receptor in papillary thyroid carcinoma and its clinicopathologic significance,” which was published in Endocrinology and Metabolism [1]. We reported the expression of the glucagon-like peptide-1 receptor (GLP-1R) in papillary thyroid carcinoma (PTC) tissues based on immunohistochemical (IHC) staining. However, we could not find a meaningful relationship between clinical prognostic markers and GLP-1R expression in PTC, but the less multifocality of GLP-1R expression in PTC tissues. These findings were unexpected and interesting because previous studies reported that GLP-1R is not expressed in thyroid follicular cells and GLP-1 plays a possible role in cell proliferation and apoptosis in pancreatic β-cells. IHC staining is well-established and used widely for identifying specific pathological processes, including protein expression nevertheless, the pathologist’s interpretation is subjective. To convert the subjective perception of IHC marker expression into quantitative data, various semiquantitative scoring systems have been suggested. For example, in breast cancer, representative tumors were subjected to several IHC stains, including estrogen receptor (ER), progesterone receptor (PR), HER2, and Ki67. Pathologists use the quickscore, modified H-score, immunoreactive score and Allred score [2,3] as generally accepted standard interpretation guidelines for IHC staining of ER and PR. In Allred score, pathologists score the proportions of ER-positive immunoreactive cells into six categories (0, no cells are ER-positive; 1, ≤1%; 2, 1% to 10%; 3, 11% to 33%; 4, 34% to 66%; and 5, 67% to 100% are ER-positive) and intensity into four categories (0, negative; 1, weak; 2, intermediate; and 3, strong). The final score is the sum of these two scores, where the minimal standard hormone receptor-positive score is 3 and the mandatory minimum of tumor cells is 1% regardless of intensity. A similar approach was demonstrated in “quickscore,” modified H-score system, with the differences in values in proportion category A from 1 to 6 (1, 0% to 4%; 2, 5% to 9%; 3, 20% to 39%; 4, 40% to 59%; 5, 60% to 79%; and 6, 80% to 100%) and using multiplication for final scoring [2]. However, the generally accepted interpretation guideline for IHC staining of HER2 is different. Pathologists evaluate the immunoreactive pattern (complete vs. incomplete circumferential membrane staining), intensity (none,