[Endosonographic imaging of tumor thickness in oral squamous cell cancer and its effect on the incidence of lymph node metastases]

Abstract

Background: The correlation between increasing tumor thickness and lymph node metastases as well as reduced survival in oral cancer has been proven by several studies. In most investigations the tumor thickness was assessed in histological sections. The aim of our prospective study was to assess tumor thickness in oral squamous cell carcinoma (OSCC) by intraoral ultrasonography and to evaluate the predictive value of tumor thickness for incidence of cervical lymph node involvement and survival.

Patients and methods: A total of 64 patients with primary carcinomas of the oral cavity (stage I-IV) were included. Endosonographic assessment of patients was carried out using a 7.5-mHz probe (Hitachi EUP F334). The primary tumor could be visualized in all cases as a hypoechoic, sometimes irregular mass.

Results: The average tumor thickness in all tumors was 14+/-7 mm. The N+ patients showed a greater tumor thickness (15+/-7 mm) than N0 OSCCs with 12+/-6 mm (p =0.032, t -test). Less advanced T1/T2 carcinomas revealed a tumor thickness of 10+/-5 mm in contrast to T3/T4 carcinomas with 16+/-7 mm (p <0.001, t-test). The overall survival was reduced in patients with tumors thicker than 14 mm (48.9 versus 28.3 months, p =0,0102 log rank test).

Conclusion: Although this technique facilitates the accurate assessment of tumor thickness in OSCC, only in less advanced tumors could endosonography provide additional information, since these tumors were not visible on CT or MRT scans. Nonetheless endosonography is a fast, cost-effective, and reliable technique for assessment of tumor extent in oral cancer.