Question

1. What is metastasis?
2. Most cancer deaths (~90%) are caused by the spread of cancer rather than the primary tumor. Why do you think that is?

Answer 1

Answer - metastasis is the spread of cancer cells from the site of origin to other bofy parts either via blood or lymph or through coelomic spread .

Metastasis occurs in three ways-

Coelomic spread- cancers which spread by invading through the serosal wall of coelomic cavity ,the cancer cwlls are carried in coelomic fluid and get embedded in other body parts m such cancers are Ca. Stomach , Ca. Ovary etc

Hematogenous spread - most sarcomas spread through this route . The cancer cells travel through blood and get embedded at other sites . Cancer cells spread via systemic veins, portal veins , arterial spread.

Lymphatic spread - carcinomas soread via lymph . The cancer cells invade the walls of the lymphatic vessels or form form emboli which is carried from one draining node to another.

Metastasis is the most common cause of cancer deaths as the cancer cells spread from the origin and embedd at several body sites spreading the cancer . Only malignat tumours show metastasis , benign tumours do not. The metastatic cancer cells invade other organs or tissues and destroy them and the surroundings . Once metastatic cells undergo rapid division at the site of lodgement ,the cancer cannot be localised , it rapidly spreads and cannot be controlled . Metastasis do not necessarily produce any Symptoms and cannot be detected early in the course of spread , which makes it even more dangerous . Metastatic tumours are treated by radiation therapy and chemotherapy . Surgery is not possible for widespread metastasis to lungs ,brains or other organs. Only palliative therapy is the treatment. On the other hand a tumour which has not metastasised can be removed surgically without compromising function .

Like lung cancer can spread to brain ,causing brain cancer , or to bones causing bone cancer .

If this helps please give it a positive rating thank you!