Evaluation of Serum Substance P Level and Tissue Distribution of NK-1 Receptor in Papillary Thyroid Cancer

Background: papillary thyroid carcinoma (ptc) is the most prevalent malignancy of the endocrine system. this study was aimed at evaluating the serum substance p (sp) levels, the tissue distribution of neurokinin-1 receptors (nk1-r), and their possible diagnostic value in ptc. method: the present case-control study included 31 healthy volunteers and 31 cases (age range: 25-64, 40.26 ±12.77), who were primarily diagnosed with ptc and were candidates for total thyroidectomy. pre-operative serum level of sp was measured using a commercial elisa kit. the tissue distribution of nk1-r was assessed immunohistochemically. results: the serum level of sp in the patient group was higher than the healthy volunteers (p = 0.005). besides, the expression of nk1-r was higher in tumoral tissues compared with their normal surroundings (p = 0.005). however, we observed no significant correlation between either sp level or nk1-r expression and the disease stage or lymph node involvement. conclusion: sp level and nk1-r expression were upregulated in ptc patients, showing the involvement of sp/nk1r complex in ptc pathophysiology. nonetheless, proposing sp/nk1r as a diagnostic factor requires further studies because we found no correlation between sp/nk1r and clinical stage or lymph node involvement.