Explain what is meant by metastasis.

Explanation

The cancerous cells of malignant tumour initially show slow growth called the latent stage, but later their growth becomes very rapid causing over-crowding and damage to the normal cells. This phase of secondary rapid growth of cancer cells is called metastasia. In this, the cancer extends to the neighbouring tissues like the roots of a tree. Small pieces of primary tumour break off and are carried to other parts of the body by the blood or lymph, where these form the secondary tumours.