Expression of potential therapeutic target SSTR2a in primary and metastatic non-keratinizing nasopharyngeal carcinoma.

Somatostatin receptor 2a (SSTR2a) is an important diagnostic and scintigraphic marker in several tumors, as well as a potential therapeutic target. However, the expression and clinicopathologic significance of SSTR2a in nasopharyngeal carcinoma (NPC) remain unknown. The expression of SSTR2a was retrospectively analyzed in a large series of NPC tissue samples (106 primary NPC samples, comprising 99 primary non-keratinizing NPC (NK-NPC) and 7 keratinizing NPC (K-NPC) samples, and 41 metastatic NPC samples) by immunohistochemistry, with 24 cases of normal nasopharyngeal mucosa tissues used as a control group. Normal epithelia in nasopharyngeal mucosa were negative for SSTR2a in all 24 cases. The expression of SSTR2a in primary NPC was correlated to the histological subtype. Most cases of primary NK-NPC showed expression of SSTR2a (93.9%, 93/99 cases). The percentage of SSTR2a-positive tumor cells ranged from 10 to 100%, while the intensity ranged from 2+ to 4+. None of the primary K-NPC samples showed SSTR2a expression (0/7, 100%). All cases of NPC showed negative expression of other neuroendocrine markers, including synaptophysin, chromogranin A, and CD56. Of all 41 cases of metastatic NK-NPC lesions, SSTR2a expression is concordant with that of the primary lesions, which shows statistical significance (p < 0.001). Our observations expand the spectrum of recognized SSTR2a-positive tumors and demonstrate for the first time that SSTR2a is frequently expressed in primary and metastatic NK-NPC, highlighting its potential as a scintigraphic and therapeutic target in this disease.