Question

Explain what is meant by metastasis?

Answer 1

Metastasis is a term associated with cancer.

Cancer is a disease which can be defined as a disease caused due to uncontrolled division and proliferation of cells without any differenciation.Cancer can be caused at any age by certain agents or due to a sudden mutation in a person genes. The cancer causing agents are called carcinogens and the gene which causes cancer in a person is called oncogene. It is believed that each one of us has oncogenes which are in an inactive or latent state but can be triggered to become active due to carcinogens.

Carcinogens are of following types:

i]Chemical agents-- eg. nicotine, aniline dyes, benzopyrene etc.

ii]Physical agents-- UV-rays, X-rays and gamma rays

iii]Biological agents-- oncogenic viruses, some parasites

Cancer cells divide repeatedly since they have lost contact inhibition. This results in a mass of tissues called tumor. As a result of this the affected part cannot function properly and cause various symptoms in the patient. If detected early, there are treatments like chemotherapy and radiation which help to slow down the growth of cancer cells. Sometimes, surgical removal of the affected part proves to be a successful cure from the deadly disease eg. breast cancer, uterine cancer etc. Luckily, in some people cancer is detected early and treatment is possible.

Based on the extent of spread of cancerous cells in the body ,oncologists categorise cancer into four stages-- Stage one,two, three and four.

Stage four is considered the last stage of cancer i.e.when the cancer cells have spread and infested other parts of the body. This happens when cancer cells pass out from the initial tumor to new sites forming secondary or metastatic tumor.

This invasion of cancerous cells from one tumor to other parts by body fluid is called metastasis. This is stage four cancer or 'advanced cancer' and a stage where there is no hope of the patient's survival.

A unique thing about metastasis is that when the cancerous cells invade other parts, they actually develop into a tumour which has similar cells as in the initial tumor. This means that if breast cancer metastasizes to the lungs, the secondary tumor is made up of abnormal breast cells and not of abnormal lung cells.