Tumours A tumour is a mass of new tissue growth that does not react to normal controls or the organizing influence of other tissues, and it has no useful function in the body. This applies to both types of tumours, malignant and benign. Malignant, also known as, cancerous tumours, are additionally defined by their invasion of local tissue and their ability to spread to other parts of the body. Benign Tumours A benign tumour which is not cancerous, is less serious than malignant tumours because they do not spread to other parts of the body, but they may cause damage by local growth and pressure on other structures, producing serio