Tumour thickness in oral cancer using an intra-oral ultrasound probe.

Objectives: To investigate tumour-thickness measurement with an intra-operative ultrasound (US) probe.

Methods: A retrospective data analysis was undertaken for a total of 65 patients with a T1-2 oral cavity cancer, who were seen at a tertiary referral centre between 2004 and 2010. The correspondence between tumour thickness measured by ultrasonography and histopathology was assessed by Pearson's correlation coefficient, and also between tumour thickness and the development of neck metastasis.

Results: In 11 cases, intra-oral measurement was not optimal due to limited mouth opening (n=2) or impossibility to depict the lesion (n=9). Tumour thickness measured by US correlated well with histopathology (n=23, R=0.93). Tumour thickness of ≤7 mm carries a risk of lymph node metastasis of 12%, whereas in tumours exceeding 7 mm this risk is 57% (p=0.001). Twenty-five percent developed neck metastasis and 19% had local recurrence.

Conclusion: Tumour thickness is an important predictive marker for lymph node metastases. As such, it can help in decision-making with regard to management of the primary tumour and neck. Based upon our findings, a wait-and-see policy is only warranted for superficial lesions with tumour thickness of less than 7 mm, but only if regular follow-up using US-guided aspiration of the neck is ensured.