Q.Explain what is meant by metastasis.

Metastasis is the process by which cancer cells break away from the primary (original) tumour, travel through the body via the bloodstream or lymphatic system, and establish new, secondary tumours in distant organs or tissues. This is what makes a cancer malignant and life-threatening — a localised tumour can often be surgically removed, but once cells have metastasised, the disease becomes systemic and much harder to treat.

The key steps in metastasis are:

• Invasion – Cancer cells secrete enzymes that digest the surrounding extracellular matrix, allowing them to push through the basement membrane and into nearby blood or lymph vessels.
• Intravasation – The cells enter the circulation.
• Survival in circulation – Most circulating tumour cells are destroyed by the immune system or by mechanical stress, but some survive. …

To understand metastasis, you first need to picture a normal, healthy cell. In a well‑regulated body, cells divide only when needed, stay where they belong, and die when they are old or damaged. Cancer disrupts this order. A cancerous cell loses its ability to control division and, critically, its ability to stick to its neighbours. This loss of adhesion is the first step on a dangerous journey.

Metastasis is not just a single event — it is a cascade. The primary tumour grows, and some of its cells begin to break away. They do this by secreting enzymes that digest the surrounding extracellular matrix, the ‘glue’ that holds tissues together. Once free, these cells can enter the bloodstream or the lymphatic system. This is called intravasation. Think of it as a rebel cell slipping through a broken fence and onto a highway.

Once inside the circulation, the cancer cell faces a hostile environment. Immune cells may attack it, and the sheer force of blood flow can destroy it. Most circulating tumour cells do not survive. But a few are hardy. They travel until they reach a narrow capillary where they get stuck. There, they squeeze out of the vessel — a process called extravasation — and enter a new tissue.

Now the cell must adapt. It cannot simply grow anywhere; it needs a supportive environment. This is where the concept of the ‘seed and soil’ hypothesis becomes useful. The cancer cell (the seed) will only thrive in a tissue (the soil) that provides the right conditions — the right blood supply, growth factors, and chemical signals. This is why certain cancers tend to metastasise to specific organs. For example, breast cancer often spreads to bone, lung, liver, or brain, while colorectal cancer frequently goes to the liver first.

Method: Root Words + Numbered Checklist

Break the term down linguistically first, then walk through the process as a short numbered

checklist — two independent memory hooks instead of one long narrative.

Etymology: meta- (Greek, "beyond"/"change") + -stasis ("standing", "position") →

literally, "a change of position." That single translation already tells you the definition:

cells moving to a new position in the body.

The process, as a checklist:

1. Detachment — a cancer cell loses its normal adhesion to neighbouring cells.
2. Invasion — it secretes enzymes that break down the surrounding tissue matrix.
3. Intravasation — it enters a blood vessel or lymphatic vessel.
4. Survival in circulation — most cells are destroyed here; a few survive.
5. Extravasation — a surviving cell exits the vessel at a distant site. …