Is the invasive front of an oral carcinoma the most important area for prognostication?

The prognosis for patients with oral squamous cell carcinomas is difficult to predict. There is therefore a great need for more reliable prognostic markers which will be of help in the treatment decisions. In this review I present a hypothesis which suggests that molecular and morphological characteristics at the invasive front area of various carcinomas may reflect tumour prognosis better than other parts of the tumour. It is now known that several molecular events of importance for tumour spread like gains and losses of adhesion molecules, secretion of proteolytic enzymes, increased cell proliferation and initiation of angiogenesis occur at the tumour-host interface (invasive front). Consequently, our group has recently developed a simple morphological malignancy grading system that restricts the evaluation to the deep invasive front area of the tumour. Several studies have shown that this system is a significantly better predictor of prognosis than traditionally used morphological systems. All studies performed so far show that invasive front grading is a valuable supplement to clinical staging, suggesting that it should be introduced into the clinic.