Muscle invasion as a reliable prognostic marker of oral squamous cell carcinoma: A clinicopathological study

Recent advances in the field of head and neck cancer have identified depth of invasion (DOI) and worst pattern of invasion (WPOI) as important prognostic/predictive factors in oral cancers. Muscle invasion, which has a better reproducibility, can be a suitable alternative as a predictor of biological behavior, especially if combined with WPOI. There is sparse literature available regarding its prognostic significance.

We analyzed 35 cases of oral-squamous-carcinomas, where the presence or absence of muscle invasion was correlated with other prognostic factors, with respect to nodal positivity and advanced stage.

The positive predictive values (PPV) of DOI, WPOI, and muscle invasion in relation to lymph node metastasis were 42.3%, 64.7%, and 47.8%, respectively. The PPVs of DOI, WPOI, and muscle invasion in relation to stage were 57.7%, 70.6%, and 65.22%, respectively. The negative predictive values (NPV) of DOI, WPOI, and muscle invasion in relation to nodal metastasis were 88.89%, 94.44%, and 91.66%, respectively. The NPVs of DOI, WPOI, and muscle invasion in relation to tumor stage were 66.67%, 66.67%, and 75%, respectively. PPV of muscle invasion was higher than that of DOI. WPOI and muscle invasion were combined and correlated with nodal positivity/high clinical staging. The PPV (71.42% and 85.71%) was significantly greater than these parameters alone and was more significant than DOI. The NPVs (90.47% and 76.19%) were also significantly higher.

WPOI along with muscle invasion in squamous cell carcinoma could be a supplement to DOI in predicting lymph nodal metastasis and tumor stage.