What do the different behaviours mean?

There are four types of behaviour:

Benign

A benign tumour is usally a slow-growing tumour that may displace but does not invade or infiltrate surrounding tissue; a tumour considered not to have malignant or invasive potential.

In-Situ

An in-situ tumour is one with malignant potential which has remained confined to the tissue in which it originated.

Invasive (also known as Malignant)

An invasive tumour is one that is not (or is no longer) confined to the tissue in which it originated. Most tumours are invasive.

Uncertain

An uncertain tumour is one which, at time of diagnosis, cannot be classified as either benign or malignant.