Mu and Kappa opioid receptor immunolabeling indicates the prognosis of oropharyngeal squamous cell carcinoma: A cross-sectional observational study.

BACKGROUND: Opioids are the most effective drugs currently available for cancer pain management. The administration of morphine, in addition to its analgesic effect, can alter tumor development. OBJECTIVE: To characterize the immunoexpression of opioid receptors micro and kappa in oropharyngeal squamous cell carcinoma, and correlate it with prognostic factors, proliferation markers, and cell death. MATERIALS AND METHODS: A retrospective, cross-sectional observational study was carried out with 50 patients diagnosed at Haroldo Juacaba Hospital. Sociodemographic, clinicopathological, and overall survival data were collected, and excisional biopsies were taken for immunohistochemistry using tissue microarrays for opioid receptors micro and kappa, Ki-67, and caspase-3. Immunolabeling was evaluated and correlated with other variables using Mann-Whitney, Kruskal-Wallis, Spearman correlation, log-rank (Mantel-Cox), and Cox regression tests. RESULTS: Immunoexpression of opioid receptors micro and kappa, Ki-67, and caspase-3 was significantly higher in p16+ and p16- primary tumors and lymph node metastases than in surgical resection margins. The overall survival of patients with p16- tumors was 57.53 +/- 8.43 months and that of patients with p16+ tumors was slightly higher at 75.92 +/- 11.14 months. Multivariate analysis showed that the expression of opioid receptors micro and kappa in the nucleus was directly associated with a lower and higher risk of death, respectively. CONCLUSION: We found increased expression of opioid receptors micro and kappa in tumor tissues. The nuclear expression of opioid receptors micro and kappa influences overall survival and may be a prognostic factor of oropharyngeal squamous cell carcinoma.