Recurrent/Metastatic Nasopharyngeal Carcinoma Treatment from Present to Future: Where Are We and Where Are We Heading?

OPINION STATEMENT

Nasopharyngeal carcinoma (NPC) is distinct in its anatomic location and biology from other epithelial head and neck cancer (HNC). There are 3 WHO subtypes, which considers the presence of Epstein-Barr virus (EBV) and other histopathology features. Despite the survival benefit obtained from modern treatment modalities and techniques specifically in the local and locally advanced setting, a number of patients with this disease will recur and subsequently die of distant metastasis, locoregional relapse, or both. In the recurrent setting, the ideal therapy approach continues to be a topic of discussion and current recommendations are platinum-based combination chemotherapy. Phase III clinical trials which led to the approval of pembrolizumab or nivolumab for head and neck squamous cell carcinoma (HNSCC) specifically excluded NPC. No immune checkpoint inhibitor therapy, to date, has been approved by the FDA to treat NPC although the National Comprehensive Cancer Network (NCCN) recommendations do include use of these agents. Hence, this remains the major challenge for treatment options. Nasopharyngeal carcinoma is challenging as it is really 3 different diseases, and much research is required to determine best options and sequencing of those options. This article is going to address the data to date and discuss ongoing research in EBV + and EBV - inoperable recurrent/metastatic NPC patients.

SSTR2a is constantly expressed in lymphoepithelioma-like carcinoma with squamous differentiation other than that with glandular differentiation

AIMS

Somatostatin receptor 2a (SSTR2a) is an important diagnostic marker of meningioma and neuroendocrine tumours and is frequently expressed in primary and metastatic non-keratinising nasopharyngeal carcinoma (NK-NPC). Since NK-NPC cases are considered a kind of lymphoepithelioma-like carcinoma (LELCs) which originate from the nasopharynx, information on the expression profile of SSTR2a in LELC in other sites with squamous and glandular differentiations is still lacking. This study aimed to assess the expression of SSTR2a in LELC of various organs and clarify its expression profile.

METHODS

Expression of SSTR2a in 164 cases of LELC was retrospectively analysed by immunohistochemistry in paraffin-embedded tissues, including 146 cases of LELC with squamous differentiation (120 cases of the nasopharynx, 21 cases of the lung and 5 cases of the parotid gland) and 18 cases of LELC with glandular differentiation (15 cases of the stomach and 3 cases of the liver).

RESULTS

We found that all (100%) cases of LELC of the lung (21/21) and parotid gland (5/5), and 93.3% (112/120) cases of LELC of the nasopharynx showed a diffused and strong expression of SSTR2a, while cases of gastric (0/15) and biliary (0/3) showed no SSTR2a expression.

CONCLUSION

SSTR2a is constantly expressed in LELC with squamous differentiation, but not expressed in LELC with glandular differentiation. However, the selective expression mechanism of SSTR2a remains unknown, which needs further investigation. Our novel findings might provide potential therapeutic approaches for the treatment of LELC with squamous cell differentiation.