The internationally recognised American Joint Committee on Cancer (tumour–node–metastasis) staging system utilises tumour size to determine stage. Other factors (i.e. tumour depth) may provide additional prognostic information.

A thorough retrospective analysis was performed of 68 patients with primary lip squamous cell carcinoma operated on or discussed by the Darling Downs Health Service between 2005 and 2013.

Twelve patients developed lymphatic spread. There was a statistically significant increased risk of nodal metastasis in: patients with tumours of increased thickness (U = 103.50; degrees of freedom = 68; p < 0.001), those with a larger overall tumour size (U = 163.50; degrees of freedom = 68; p = 0.005) and patients living further from the treatment centre (U = 199.00; degrees of freedom = 68; p = 0.018).

It may be reasonable that other factors are considered for staging of lip squamous cell carcinomas, in combination with tumour–node–metastasis staging. Depth of invasion may have utility in prognosis and treatment; however, larger prospective analysis needs to be performed. Patients living in a more rural setting presented with more advanced disease, suggesting an ongoing rural–metropolitan gap in healthcare.