Discussion
Our research found a significant correlation between lymph node metastasis and the stage of the LSCC tumor (p=0.001). Redaelli et al. studied the occult neck lymph node metastasis in LSCC patients and found an incidence of 39.2% (6). This result was significantly correlated with the stage of the tumor (P= 0.04). Yilmaz et al. study results are also consistent with those of ours (7).
Our results showed that 91.6% of the subjects that had cervical lymph node EGFR expression in their metastasis had a primary with moderate to poor differentiation. It was also revealed that there is a strong association between tumour grade of differentiation and the cervical metastasis (p=0.001). Magnano et al. reported that the poorer the differentiation was, the higher the possibility of cervical node metastasis would be (8).
On the other side, we did not find evidence of statistical nor clinical correlation between the age and the gender with the EGFR expression state in the lymph nodes. Similarly, (Čelakovský, Kalfeřt, Smatanová, et al., 2015) did not postulate age nor gender correlation with the cervical metastasis in laryngeal cancer patients. (9)
Also, we did not reveal any statistically significant correlation between the site of the primary and the cervical. This was in consistency with the study results of Čelakovský et al. who did not postulate a relation between tumor sub-site and EGFR expression in the cervical metastasis (9). In contrast, Mayers & Allvi reported that transglottic and supraglottic carcinoma cause early cervical lymph node metastasis that they recommended lateral neck dissection with the laryngectomy surgery having a desirable effect on the prognosis (10).
We found a positive correlation between lymphovascular invasion and EGFR expression in the cervical metastasis (p=0.028). This is in congruity with the results of Ozdek et al which found that lymphovascular invasion is a risk factor for occult metastasis and is a histological feature that indicates an aggressive behavior of the carcinoma as tumor cells access the blood and lymph vessels causing lymphatic and distant spread altering the prognosis of the patients (11).
We examined the membranous expression of EGFR in the LSCC primary tumor masses using immunohistological analysis. It was revealed that 70% of the specimens had positive reaction to the EGFR antibody. Zimmermann et al. asserted that nearly 80% of the head and neck carcinomas are associated with an elevated expression of EGFR (12).
We noticed that 100% of the study sample who revealed to have positive EGFR expression in their cervical lymph node metastasis had positive membranous EGFR expression in their primary tumor with statistically significant correlation (p=0.001). Şimşek H et al correlated the aggressive behavior the tumor expresses in the matters of poorer differentiation, increased tumor volume and cartilage, lymphovascular and muscle invasion and metastasis to tumor EGFR expression(13).