The association between RCAS1 expression in laryngeal and pharyngeal cancer and its healthy stroma with cancer relapse

A total of 122 tissue samples were obtained: 51 samples from laryngeal and pharyngeal squamous cell carcinoma, 51 samples from the clear surgical margins of these tumors, and 20 tissue samples derived from the healthy mucous membranes of the upper respiratory tract mucosa of patients without cancerous tumors. Patients were observed for a total of 4 years following surgical treatment. The level of RCAS1 expression was assessed by immunohistochemistry and Western blot.RCAS1 was identified in all laryngeal and pharyngeal carcinomas and in almost all the clear surgical margin samples. The level of RCAS1 expression was significantly higher in the cancerous samples than in the clear surgical margins and was determined to be related to the grade of the cancer and the presence of lymph node metastases. In cases of cancer relapse, significantly higher levels of RCAS1 expression were observed in the clear surgical margins.Selective cytotoxic immune cell suppression concomitant with tumor growth and associated with RCAS1 expression seems to be an important event connected with cancer relapse.Head and neck squamous cell carcinoma constitutes the sixth most common type of cancer in the world [1]. The five-year survival rate for patients with this disease has not improved appreciably since the early 1980s, remaining at approximately 52% [2,3]. A common problem in cases of head and neck cancer is the recurrence of the disease either in the location of primary surgical resection (although the surgical resection margins were histopathologically free of cancer cells) or in another place. The risk of a local recurrence of the disease is still high, approximately 10–30% [4].Tumor-associated antigen RCAS1 (receptor-binding cancer antigen expressed on SiSo cells) is a type-II membrane protein, expressed in various human cancer cells [5]. It has also been detected in blood serum in a soluble form (sRCAS1) that is probably released from the membrane form as a result of ectodomain shedding