Significance of Worst Pattern of Invasion-5 in Early-Stage Oral Cavity Squamous Cell Carcinoma

There is an ongoing need to identify pathologic prognosticators in early-stage oral cavity squamous cell carcinoma (OCSCC) to aid selection of patients who may benefit from adjuvant treatment. The objective of this study was to evaluate the prognostic ability of worst pattern of invasion-5 (WPOI-5) defined by the presence of satellite nodules, extratumoural perineural invasion (PNI) and/or extratumoural lymphovascular space invasion (LVI) in low-stage, node negative OCSCC.

This was a retrospective study of 160 patients with T1/T2N0 tumours staged using TNM7 treated surgically. Histology of the primary tumour was re-reviewed as appropriate to assess for the presence of WPOI-5 parameters. Univariate and multivariate analysis assessing impact of pathological features on survival outcomes was performed.

On univariate analysis, WPOI-5 and its 3 constituent components of satellite nodules, extratumoural PNI and extratumoural LVI were all significantly associated with disease-specific survival (DSS) and overall survival (OS). On multivariate analysis, satellite nodules (odds ratio 6.61, 95% CI 2.83-15.44, p < 0.0001) and extratumoural LVI (odds ratio 9.97, 95% CI 2.19-45.35, p = 0.003) were independently associated with OS. Postoperative radiotherapy (odds ratio 0.40, 95% CI 0.19-0.87, p = 0.02) and non-tongue subsite (odds ratio 3.03, 95% CI 1.70-5.39, p = 0.0002) were also significantly associated with OS on multivariate analysis.

Satellite nodules and extratumoural LVI correlated significantly with survival outcomes in our early-stage OSCC cohort. Further study is required to investigate the benefit of adjuvant treatment in these cases and to ascertain if WPOI-5 parameters including satellite nodules should be mandatory reporting data elements.